William Wynne

The Corvair Authority
5000-18 HWY 17 #247
Orange Park, FL 32003

Ask The Authority!

William is now receiving about 30 e-mails daily inquiring about Corvairs. Many of these e-mails come from different people asking the same question that has already been answered here, so we did not think people were actually reading this page. Imagine our surprise when people wrote in asking if William was still in business because nothing had been posted here since November. So due to this popular demand, the daily Q&A posting will resume. Just take a look here first for your question before e-mailing. And you can see we're still in business at the Online Catalog Page, where we have new products available for you including light weight aluminum oil pans and remanufactured distributors outfitted with dual points plates, and now prop hubs available through PayPal. If you don't see your question answered here, then by all means e-mail William at WilliamTCA@aol.com. Thank you.

Subj: Corvair Knowledge Needed
Date: 11/6/02

I am a member of 5 builders in the Atlanta area building 5 Pietenpols at one time. We are interested in Corvair conversions. Where do we start? We have no knowledge of anything Corvair related, so where do we go from here? It seems most people in your group are already up-to-speed, but we have to start from scratch. Help!

Barry D., Atlanta, Pietenpol
Reply from WW:
The best way to come up to speed is to get a copy of the Conversion Manual from us. The Corvair and the Pietenpol are a match made in heaven. In the Atlanta area, our friend and Pietenpol builder Skip Gadd has a half built Corvair motor and Piet well on its way in case you guys want to drop in and see what one looks like. We also have a 1-hour video tape which is an introduction to the engine and its installations. The video and Manual are both available at flycorvair.com Catalog of Parts Available from The Corvair Authority . I'll be glad to answer any question you have, and if you're going to be in our neck of the woods, certainly feel welcome to come by the shop for a visit. My own Piet flew nearly 900 hours on Corvair power. We logged 400 of these in the last 2 years we had it. This should be a very good indication of the reliability and dependability of the combination. While I love the sound of Ford powered Piets, being able to hop in and turn the key and cruise at 80+mph makes the plane a lot more useful.

Subj: Helicoils
Date: 11/5/02

I am having trouble deciding which helicoils to order for my headbolts. Could you help me find the correct p/n at Clarks? (2 types are listed) I would certainly be interested in the stainless steel studs you have in stock. Do you have the helicoils in stock also?

Dave, 150pilot@suscom.net
Reply from WW:
Use the longer of the 2 helicoils. I no longer have any stainless studs and they were real slow sellers, so I'm not planning on restocking. When rethreading the bottom of a stock stud, make sure you use a new die and real cutting oil. It makes all the difference.

Subj: Size And Data Markings
Date: 11/4/02

Please tell me where the data or year markings are on the Corvair engine? I have found one but have not identified it yet, it's about 40 miles from me. Thank you.

Palmer, QUIDGROVE@aol.com
Reply from WW:
Sorry about the delay in returning your e-mail. If you stand behind the car, the letter code is on the case just in front of the oil filler tube. The area can be quite dirty and covered in goo. The trick I always use to keep my hands clean is to pull out the dipstick and use it as a mini scraper. The new Manual contains detailed information on engine selection and ID.

Subj: Murphy Rebel
Date: 11/3/02

I'm considering building a Murphy Rebel and to keep costs in the realm of reality, I'm thinking of using a Corvair conversion for power. It seems reasonable as the version I'm thinking of is the lightweight UL model that has succesfully flown with a Rotax 912UL. Do you know of anyone else working on this combination? How does it look to you? Many thanks and thanks for a great, informative web site.

Oscar L., oscar@waggonerguide.com
Reply from WW:
I've liked the Murphy Rebel since its introduction. Certainly a good, solid airplane. I believe it would be an excellent candidate for a Corvair motor. While we've had several inquiries about it, there's no one currently flying a Corvair in a Rebel that I know of. The plane is even more attractive when you consider the cost difference between a 912 and a Corvair to be about $7,500 in your pocket.

Subj: Davis DA2
Date: 11/2/02

thanks for the news letter and keep up the good work.hope to meet you in florida some day.one question i have is will a corvair fit in a da2a davis cowl without having to change the shape of the cowl.have any experience with the davis? do you feel its a good design? i realize the answer to my cowl question lies in my breaking out the ruler and doing some figuring but i thought you might have gotten a look at a corvair davis somewhere.

Ken C., West Hurley, N.Y., DA2
Reply from WW:
The DA2 is a great little airplane, a particular favorite of mine. A gentleman in Oklahoma has 400-500 hours of time on his Corvair-powered DA2, enough to tell you it was enjoyable to fly and reliable. I've seen pictures of his airplane, but nothing I could tell you much about the cowl from. My suspicion is that with the Corvair several inches narrower than any of the Continentals, it would fit right inside the stock cowl. In the last issue of Sport Aviation, there was an excellent photo of a DA2 in flight. Truly a pretty and simple airplane.

Subj: Titusville, Fla., Chapter 866 Demo Wednesday
Date: 11/1/02

Thank you for inviting me to speak at your EAA Chapter 866 meeting 7:30 p.m. Wednesday, Nov. 6. You can count on me being there, just give me directions. Have no fear: Out of hundreds of forums I have given in the past 8 years, I have never canceled one, been 5 minutes late only twice, and the only one that ended early was because the organizers closed Sun 'N Fun '99 early one day because of choking smoke from brush fires!

Looking forward to meeting your Chapter.
Reply to WW:
Hey great, I know the membership will be looking forward to your visit. We are located at X-21, Arthur Dunn Airpark, Titusville, Fl. Take I-95 south to exit 80, which is the Garden St. exit. Take Garden St. east. After passing through one traffic signal (Singleton Ave.), start looking on your left for Williams Ave. It is probably 4-5 streets east of that traffic signal. Also, there is a large billboard on that (Williams) corner advertising a restaurant named Joy Buffet. Turn left on Williams Ave. Proceed north (less than a 1/4 mile I would guess) over 3 speed bumps (by now you're looking right down runway 33) and just before the road starts to curve to the right, pull into the FBO/Jump Center parking lot. We are located on the right (next to the flag pole) in Bldg. 10, EAA 866 Chapter Bldg.
This meeting as I mentioned is on Wed., Nov. 6, 2002, at 7:30 p.m.
We will have a short business meeting, greet visitors, etc., and then turn it over to you. Hopefully you're bringing your engine on a test stand? We could then get up close and personal to your conversion.
Thanks in advance,
Sincerely, Steve
P.S. I was choking with you at SNF 99. I drive for the on site shuttle/tram volunteers!

Subj: Corvair weight
Date: 10/31/02

What is the weight of a Corvair electric start, vs C-85 A-65. Thanks.

Bob B., ra_balke@hotmail.com
Reply from WW:
A Corvair motor ready to fly with electric start and alternator weighs about 225 lbs. with oil in it. A hand prop 65 Continental is 35 or 40 lbs. less than this. A C-85 is about the same, if it is a -8 hand prop engine. The -12 C-85 with a full electrical system weighs virtually the same as an O-200 or Corvair.

Subj: Carburetors
Date: 10/30/02

Just got a new carburetor off a Harley.Going to give it a try and retire the Aerocarb. The Aerocarb has been nothing but trouble - it has had three slides, five needles, two throttle cables and three different intake manifolds and still no joy. I'll let you know the outcome. Have about 20 hours now.

Glen D., Plainfield, Ind., Sonerai 2
Reply from WW:
Sorry to hear about your trouble with the Aerocarb. A handful of guys are saying that it works well, but no one is flying it like you are and I think that it is easier for people to get it to work on a longer manifold without a pump or regulator. You may want to try a little more volume in the intake, or a slightly different shape. I have not done that much with short manifolds on top of the motor, but they did prove to be more prone to pulsing than longer ones. Changing the length or volume affects this.

Subj: Pistons
Date: 10/29/02

My question is about pistons. As you may know, OEM piston technology has come a long way in 10 years, let alone the past 40. I have been advised that new pistons made to order using modern materials, coatings & processes cost only a couple of hundred dollars more than stock replacement parts for a 6 cylinder. Do you think that a set of these with a heat barrier coating on top would be useful in a Corvair conversion from a standpoint of durability and reliability, considering that the engine is air cooled and may help the pistons run cooler?

Reply from WW:
I'm sure that modern coatings would help the motor, but at the modest output we require, it's not really an issue. My primary concern is that the motor would never lose any of the coatings in operation. Reliability is everything in airplanes. The only pistons we use are TRW forged pistons. All original pistons were cast, even the turbos. There are more modern piston designs for the Corvair, but none are as strong as the TRW.

Subj: Getting into corvairs
Date: 10/28/02

I hear nothing but good things about you from some of your friends whom I met at the "Field of Dreams" fly-in. OK, I've been with this guy named "Pat" for a couple of these events and I am building a Dragonfly. Although I have a torn down Subie stored in the garage, I'm now convinced that a Corvair is the way to go for my high altitude location (Denver).

I have already begun the search for a boat anchor engine. On the first day I found a wrecking yard in Kansas that has 24 Corvairs, but all '64 and earlier. The search will continue.
I also know I will need one of your books on making the conversion. That order will be placed in the near future. In the meantime I wanted to introduce myself and let you know that your knowledge and expertise is valued and I look forward to learning a great deal from you.
Paul, Denver, schumpa@juno.com, Dragonfly
Reply from WW:
I just came across your very nice introduction letter, thanks. Actually 1964 is an acceptable year to use. It is a 164cid motor just like the '65 to '69s. I have built many of them into plane motors. They have slightly smaller head gaskets, but it is nothing which would concern me on a well built motor.
Good choice to forget the Subaru. Except for top of the line $15,000 packages like Eggenfelner's RV stuff, their day has past. Most people now know that the motor never made the power its advocates claimed and that the final installation was a lot heavier than people said. With expensive redrives, it was just as expensive as many aircraft motors. They had a 10 year run, driven by hype in magazines, but most of the companies selling them six years ago are gone.

Subj: WAR Replica Corsair
Date: 10/27/02

Hello my name is Shawn and I was interested to know if a WAR Aircraft replica Corsair which is designed for a Continental O-200 or Lycoming O-235 will accept a Corvair engine in it as I am very interested in this.

Shawn, sa919@aol.com
Reply from WW:
Your question is a fairly frequent one. The standard Corvair is a good match for any aircraft which can be flown on an O-200. In this particular application, a 190cid Corvair could probably put out nearly the same thrust as the O-235, when the O-235 is restricted to the use of a small diameter propeller. The Corvair motor is far lighter than the O-235 and several inches narrower.

Subj: Critters in the hangar
Date: 10/26/02

I thought that I would drop you a line to let you know how things are going at my hangar.
I'm afraid that my hangar is infested. Judging from the result it must be pixies or gnomes.
I discovered them from the signs that they left behind. While doing the weight and balance, I noticed that some stuff must be missing. As of my last w&b the empty wt. with all fluids was 793 lbs. The new wt. with oil is 694 lbs. Basic math confirms a total loss of 99 lbs. of some VERY expensive stuff!
Since the hangar is always locked up, logic dictates the work of gnomes (they always steal stuff). But considering the total wt. of stuff missing, I suspect they had assistance in the form of pixies (as you know they help with work while the gnomes just thieve).
But all is not lost though. Judging by the amount of stuff missing (99 lbs.) I don't think that they could have dragged it very far.
Tomorrow I will check around the pile of stuff by the Subaru engine.
Maybe I can find the missing tonnage there.
Wish me luck,
Your friend,
Bob L., Fort Lauderdale, Fla., KR2
Reply from WW:
I just called an editor of a famous kit building magazine and he assured me that you must be hallucinating because we all know that they have published dozens of article on how EA-81s actually weigh 23.45 pounds, and the liquid coolant actually has a negative mass once it reaches operating temperature (especially after it leaks out).
Get help Bob, and get it quick. The editor pointed out that with air cooling the whole atmosphere of South Florida is free to flow into your engine compartment, and this must weigh a lot more than your calculations.

Subj: Instrumentation
Date: 10/25/02

I would like to use a 4 in 1 Westach engine instrument having oil pressure, oil temp., CHT, and EGT gauges. Any problem using this instrument?

Greg J., Atlanta, Ga., Zenair 601
Reply from WW:
If your motor has a front-mount starter, I prefer the instrumentation to be all electric. The rationale for this is contained in detail in the new Manual. Westach makes reasonably good instruments at very inexpensive prices. There should be no problem at all.

Subj: Alternator
Date: 10/24/02

Would like to use an alternator which has built in regulator. What size (amp) alternator would you suggest? I'll probably go with front mounted starter and alternator.

Greg J., Atlanta, Ga., Zenair 601
Reply from WW:
Almost every 601 person we've contacted has been interested in the simplest setup possible, which is the front mount starter. My favorite alternators are the John Deeres, in 14 or 18 amp. They are very reliable. I use a solid state voltage regulator with them, and I've never had a failure of either component. Automotive starters tend to weigh 2 or 3 times as much. If you analyze your electrical load carefully, and consider that most loads are intermittent, 18 amps is plenty for most airplanes we're talking about.

Subj: Champion V
Date: 10/23/02

My grandson and I have purchased the plans for the Champion V light sport airplane of all wood construction. It is a tricycle, low wing. Gross weight is 995 lbs. and was first flown with a Limbach Sauer 75hp engine. The plans include motor mounts for a Continental C-85, C-90, and the O-200, with the notation that the engines are seldom used because of the excessive weight. JPX 80hp, Limbach VW 75hp, Rotax 90hp, VW and the Jabaru at 80hp and 100hp are recommended. The Rotax and Limbach engines as well as the Continentals, etc. are expensive. We were considering the VW, Jabaru or Subaru, but with reduction drives and the radiator for the Subaru, we feel the weights are going to be quite close.

We would like to use a Corvair for a lot of reasons. Does it sound reasonable to think of the Corvair or are weight problems likely? I brought up your site to order the Conversion Manual. Have ordered the catalogs from Clark's. We decided to check further with you first.
Bob N., Sioux Falls, S.D., Champion V
Reply from WW:
I know the Champion well by its kit name, the Pioneer 300. The people with the rights to market this are about 20 miles away from us and we've seen it many times. They were guest speakers at my EAA meeting also. I see no reason why the Corvair wouldn't be a good match. If it's approved for an O-200 and has flown with it, the Corvair will be a very good motor for it. It's certainly a beautiful airplane.

Subj: Engine blocks
Date: 10/22/02

Ever think of expanding your business and making engine blocks? Being that new internal parts are available, it would seem to me to be very profitable, not to mention convenient and affordable for homebuilders. The 6 cylinder 100hp, 200lb engine combo is hard to find, and to be honest, $10,000 for a Jabiru is ridiculous, epecially when you figure most homebuilders are working on a budget. The VW is appealling because you can get a brand new core for about $1800, it just doesn't have enough power and running a 4-cycle air cooled engine at 5000 rpm sounds a little risky to me.

Andy S., AShontz@NBME.org
Reply from WW:
Several people a month bring this up, but most Corvair cases are perfectly fine to go flying as they are. The original VW case was magnesium and engineered for absolute minimum weight. The Corvair's robust construction in aluminum tends to make most cases of core motors ready to fly without further work or expense. Thus, the market for new cases would be very small. Several years ago, I came across a brand new set of factory original cases. I tried to sell them for several months for $250 and it was a long time before I found a taker. This is simply because most core motors for $150 come with nearly the same set of cases ... and the rest of the motor.

Subj: Corvair cooling at low speeds
Date: 10/21/02

I have been reading your Web site and don't see the answer to my question as of yet. I am looking at building a Littlewing autogyro.

The corvair seems to fit the bill of 100hp min and O-200 max weight for the 2 place version. But here is the issue. This thing flies very slow with a cruise speed of 65-75 mph. Will this engine get enough cooling at this speed, and if not, how much weight does the stock cooling fan and shrouds add? The designer feels that cooling will be an issue with the Corvair engine.
John K., Reisterstown, Md., Littlewing autogyro
Reply from WW:
I can assure you that a good looking cowl can be built which will cool the motor from prop blast only at zero air speed. I break in motors on my test stand with a one hour run at 75% power while standing still. I keep them very cool with a simple baffle on top. It is boxy, but a much more elegant one could be made for a flight motor. Additionally, the best climb speed of a Pietenpol is only 55 to 60 mph. We spent many airshows hopping rides to people on hot days. Although a typical run was 90 seconds to 1,000 feet, the head temp could be held below 375 for any extended climb. Keep in mind the motor has enough cooling capacity for 180HP of heat in the car, and working it at 75 to 100HP in a plane is not a big challenge.

Subj: Fuel consumption
Date: 10/20/02

Why is the fuel consumption rather high on the entire Corvair engine? I wanna be able to use "regular" gas from the pump in my Corvair getting as much HP as I possibly can for my KR2S with the lightest weight. I would like to keep it at about 215 firewall forward. Possible?

Justin, jmw116@socal.rr.com, KR2S
Reply from WW:
I am not sure what you mean by "high" fuel consumption for the Corvair. You must burn fuel to make power. Corvair is middle of the road on fuel consumption, and if anyone is trying to tell you that they know of an engine which will produce 75 cruise HP at something like 3 GPH, they are pulling your leg.
A flying hand prop Corvair motor installation could be made as light as 215lbs., but most people want electric start, etc. Typical weight FWF in a KR is about 240. Not a big difference for the ease of starting.

Subj: Auto trans
Date: 10/19/02

Is the bell housing the quickest way to look at an engine and be able to tell if it was behind an auto trans?

Gene B., New Berlin, Ill., Pietenpol
Reply from WW:
Many engines were swapped back and forth, so you cannot really tell if a 140 auto or manual crank gear is on a crank just by which bell it currently has bolted to it.
A bellhousing which is ventilated is from an automatic transmission and one without vents is a manual. Hope this is some help. If you have a specific question about your motor, I will be glad to help if I can.

Subj: Parts needed
Date: 10/18/02

From you I need a safety shaft, hybrid studs, prop hub, castle nut, Allen bolts, spacer if needed.
Would it be best if I sent you my crankshaft so you could do all the maching needed? So it would be ready to put into the engine when I receive it from you. Or should I keep my crankshaft here and have you send me everything I need from crank to prop. My crank seams to be right on the numbers.
Please in your return e-mail would you let me know what the charges would be and if you take credit cards, bank check etc? Or whatever method of payment you prefer.
I have a 1966 110 hp with 8.25 heads. But I found a pair of 9.25-1 heads. On the jugs the #'s are:
723 65 08
723x 91 94
723 107 90
723 69 92
723 69 68
723 107 118 are they ok????
What do the #'s represent or mean?? Thanks for your book. I have read it 3 times plus scanning thru it when needed.
Ron C., Osage, Iowa, Europa
Reply from WW:
Good to hear from you. We're about a week away from the arrival of our next batch of prop hubs. All the other items you requested we have on hand. The crank can be done at your location or here. Our cranks are reground 10/10, threaded, and come with the safety shaft and hybrid studs. The price of this is $324 plus your old crank. If you have a good machine shop in your area, many people just buy the safety shaft and hybrid studs for $66 each. The prop hubs are $299, and we accept personal checks or can bill you through PayPal.
The numbers on the cylinders are casting numbers. If they came out of 164cid motors, they're fine for use. Almost every Corvair cylinder will clean up with a 20 overbore.
As long as the cylinder heads have some quench area to them, they're fine for use.

Subj: Engine choice
Date: 10/17/02

I plan on using the engine for an AirCamper on auto fuel.My problem is I have found some engines, and I know the block, crank and head IDs, but do not know if you recommend a 95hp or a 110hp for auto fuel. Also I do not know the year I need. The gentleman that has these engines is in poor health and is eager for me to get them because of the cold weather. Thanks for your help.

James W., Marion, Ind.
Reply from WW:
You are looking for any 1964-1969 110 or 95 motor. Either one will produce the same 100 HP when converted according to my Manual. The things which make these motors different - cams, timing, carbs - are all changed, thus no difference which you start with. Either motor can run on auto fuel.

Subj: Stock Carbs
Date: 10/16/02

Rinker box on Glen's motor. Ratio is 1.39 to 1 straight spur gear reduction. The 3 inch thrust line increase from the gear box make using stock carburetors possible. Stock carburetors cannot be used in a direct drive installation.
Why can't stock carburetors be used without a gear box???????
Reply from WW:
If you look at the height of the stock carb, it would make for a very blunt cowl on a direct drive motor. The Rinker box made the thrust line 3" higher because of the offset of the gears, but stock carbs are still not a good idea. If you wish to use an inexpensive carb, there are several options listed in the Conversion Manual.

Subj: Corvair for W-10
Date: 10/15/02

Hi. Was wondeering if it was a viable engine for W-10? Would consider 120 HP only way to go? Thanks
Bill H, Pedal C@aol.com
Reply from WW:
The W-10 is an exceptionally efficient airframe. It's been flown on motors as small as 85hp. Although most people today install 150hp Lycomings, Wittman intended the design to be light and flown on efficient motors. He sternly scolded people who built overweight airplanes. I feel a 100hp Corvair would be enough with a light airframe. There would be nothing wrong with the 120hp if you wish the additional performance.
We saw the original Tailwind at Oshkosh this year. It weighed 685lbs. with a full electrical system. Unfortunately, many are built today in the 950-1,000 pound range. A Corvair-powered Tailwind could certainly be built at less than 750 lbs. This should be your goal. By the way, I flew with Steve Wittman in N37SW a few months before he died. It was a very impressive experience.

Subj: Propeller
Date: 10/14/02

I will soon be building a KR2S, and I just purchased a Corvair engine. I do not know much about the subject of propellers, but was told you could help. My question is: can you use a 3-bladed prop with the Corvair engine in the KR2S and what results would occur, good or bad???...Thank You....

Jack, citisoldier@yahoo.com
Reply from WW:
The Corvair is a very popular engine choice for the KR2 and KR2S these days. Many of these builders are interested in using the 3-blade Warp Drive propeller. I'm a dealer in these propellers and highly recommend them. They're very smooth running, especially the three-blades. People argue all day long about two-blades, three-blades, prop efficiency, etc. Although it's technically correct that a two-blade prop could potentially be built with greater efficiency than a 3-blade, that's a textbook answer and not a real world experience. The 3-bladed prop in your application will provide extremely smooth operation and ground adjustable performance which will likely exceed 95% of all wood props.

Subj: 140hp motor
Date: 10/13/02

Already I have a question. I see right off the bat you indicate I should *not* use the 140 hp engine (the one with the 4 carbs on it). Too late. I saw one and bought it before I got your Manual. Is there anything positive I can do with this thing? Like purchase different heads for it and salvage the project?

Or - do you simply recommend I try to unload the thing on the auto engine market and start my search over again for the 110 hp model?
Ed N., Columbus, Ohio
Reply from WW:
I suggest keeping the motor. You are quite correct that 140 heads and carbs can be sold off to an automotive guy. You'll have more than enough money from this to buy a good set of 110 heads. Write me back with the letter code of your engine, i.e., RB, RH, RA, and I'll let you know if it was originally equipped with an automatic transmission. If it was, it will have a built in timing retard in the crank gear. I can swap this in my shop for you. Other than these two points, you're good to go.

Subj: Playboy
Date: 10/12/02

I am still interested in using a Corvair in my S3-A3 Stits. The wing has been stretched about 18 in to 22 ft. I plan on VFR daytime only, so it will have only basic instruments. I wish to keep it simple and as light as I can. I do want electric start. I have located a couple 65 Corvair engines. I guess I need your thoughts on this before I proceed. Thanks for any help.

Don Kadous, Spencer, Iowa, Stits Playboy
Reply from WW:
Since I last wrote to you I had a chance to speak with a friend who knows more about Playboys. He said that there were several different models, and although people tended to build the heavier ones, there were in fact versions which would fly well on smaller HP. Sounds like you may have one of these from your weight numbers and wingspan data. If this is the case, it should work well.
Let me know how I can be of further help. Your plan of a light, day VFR bird is a good one. Too many people plan on building heavy complex planes which they cannot finish, afford or fly.

Subj: Starters
Date: 10/11/02

The Subaru starter, it turns the same direction my engine will turn - stock, rebuilt cam, which will be the opposite direction most engines turn, right?
On your rear start engine did you use a "puck" to mount the starter ring to?
Gene B., New Berlin, Ill., Pietenpol
Reply from WW:
You are correct about this. A Corvair is one of the very few engines in automotive history that turns the direction it does. The Subaru is one of the very few starter motors of modern design that is compatible with front mount use on a Corvair. When mounted on the rear, obviously, there are numerous choices in modern starters.
Yes, I used a puck with the rear starter. I currently have a handful of these in the shop. In my experience, no ring gear is made accurately enough to sandwich between the prop hub and the crank. They will always throw the prop out of track. In my system, the highly accurately machined aluminum puck is what is between the crank and the prop hub. The ring gear is machined to bolt onto the puck.

Subj: Generator
Date: 10/10/02

I found a generator (John Deere 750, part #CH15587) that I want to use. It does not make a difference on the direction a generator turns, correct? As you may recall, my engine will be a rear mount starter/generator. I plan to use the drive v-belt pulley on the harmonic balancer.

P.S. I think a generator is a better system than an alternator. (A generator makes power whereas the alternator needs voltage to make power, right?)
Gene, Spltwind@aol.com
Reply from WW:
It doesn't make a difference which way it turns. It is an AC generator. It does not have the typical problems associated with pre-1965 car generators. It will make plenty of power from idle to top rpm.

Subj: The Vair Runs!
Date: 10/9/02

Good morning. Cranked up the Vair this morning, hit the starter button and it was running. Tweaked the idle screw a couple of times untill it stayed running. Runs good at rpm but runs rough at idle yet, so the next thing to do is fine tune the timing.(Wait until this afternoon when it's warmer, so I don't freeze in the prop blast.) Ran it for 15 minutes at different rpms and the CHT was at 246 to 260 degrees on all cylinders per handheld temp reader. Starter system worked excellent, with the 8 inch ring gear. It really spins it over fast.

One thing I would like to verify: I ran the incoming oil into the center of the oil filter, is this correct?
I just put another thing on the list...MUFFLERS! Another milestone!
Del M., New Richmond, Wisc., "Outlaw" Sonex
Reply from WW:
Generally, the oil filter inlet is the outside of the element. The center of the filter is generally the outlet side. For ground running, I wouldn't really worry about it. I've seen motors run both ways. A high quality filter should be able to take the modest oil pressure of the Corvair in either direction as long as the oil is thin. But I'd reverse it for flight.
If you have a hand held temp reader, and you want to monitor the critical temp, shoot it up from the bottom on the cylinders in the little hole in the steel baffling. This will run much higher than a cylinder head on a motor which has no top shroud on it. A lot of guys get justifiably hyped up when their motor runs. Short runs are not good for the oil system and cam break in, and long runs are not good for the bottoms of the cylinders. The best solution is to put a duct work on it like we used on top of Mark Langford's motor at the Corvair College. Although there are numerous pictures of me running engines without baffles, most of these motors are fully broken in and can take a quick start up without being hurt.
Your unique motor is a real tribute to you.

Subj: See you at Thomasville This Weekend
Date: 10/8/02

I'm glad to hear that you'll be at Thomasville this weekend. I received my Manual last week and bought a '65 110 hp engine last night. It's in a pretty sad state, but may be rebuildable. Probably an OK deal at $25.

The Davis project is just sitting. Fuselage skins, all weldements, gear, tail members, etc. done. The wings are the only major part not started (though the spar web and caps are ready for riveting).
What all do you plan to do at Thomasville? Any sort of workshop?
Hope to see you there - I plan to fly down with a couple more motorheads.
Jeff B., Atlanta, Georgia, Davis DA2
Reply from WW:
Good to hear from you. I am planning on bringing a bunch of show and tell stuff to Thomasville. We will have one Corvair-powered flying plane there and a display engine. Bring pictures of your stuff if you have some; I am interested to see what you've got.

Subj: Corvair for Merlin
Date: 10/7/02

I have a Corvair engine with 4 carburetor intake that I would like to use to replace my 2-cycle 618 Rotax on my Merlin. What do you advise?

Richard V., Potterville, Mich., Merlin
Reply from WW:
As explained in the Manual, winging its way to you now, the 4-carburetor motors are popularly referred to by their horsepower designation, the "140." These motors are not desirable for direct drive aircraft powerplants. Fortunately, almost everything in the motor, with the exception of the heads, is usable for an aircraft powerplant. The 110 heads will bolt right on this motor, and are the ones which you will use. All the casting numbers are in the Manual.
There are two aircraft that go by the name Merlin. I assume you're talking about the two seat, high wing, tractor monoplane, not the two-seat Ultralight. The first one is a good match for the Corvair. The second one I have not studied.

Subj: Playboy
Date: 10/6/02

I have a single place Playboy. Is this a good candidate for a Corvair conversion?

Don, via e-mail
Reply from WW:
The Playboy generally requires more than 100hp to fly well. It was a very early Ray Stits design, and while it is a solid plane, it is not a particularly efficient single seat platform. Unless your airframe is an exceptionally light one, I tend to think it would fly better on an O-320. Many Playboys ended up with 800lb. empty weights, quite high for a single seater. While I have the greatest respect for Ray Stits' fabric work and contributions to sport aviation, the planform and the layout of the Playboy is probably served better by higher horsepower motors.

Subj: Prop hub drive lugs
Date: 10/5/02

I want to order a prop hub, but am not sure if I need drive lugs in it.

Reply from WW:
Drive lugs are not required for the vast majority of Corvair prop applications. Years ago, we put them in prop hubs, but gradually offered hubs with a straight 3/8" hole. Only the most extreme engines would need drive lugs. I have not sold a hub with drive lugs in more than a year.
Another batch of hubs is due in about two weeks, and half are already sold. If you would like to reserve a hub, send a Liability Statement along with a check or money order for $299 (S&H is extra outside the U.S.) payable to William Wynne, P.O. Box 290802, Port Orange, FL 32129-0802. Your check won't be cashed until we ship your hub.

Subj: KR2 motor mount
Date: 10/4/02

I'm building a KR2S and I'm not a welder. Do you still offer motor mounts for this airframe?

Reply from WW:
I've built about a dozen mounts for KR2s. All of these were built and specifically tailored to individual airframes. With a lot of help from KR builders like Mark Langford and Mark Jones, I was able to distill the complex design information into a single pattern which will effectively work on the vast majority of all KR2s and KR2Ss. I've built a very heavy, close tolerance jig in which to produce these mounts. The mount is sized so that either front or rear starters can be used with it, the engine will fit in most stock cowlings, Deihl tri-gear brackets can be welded on, and standard exhaust systems can be used. Mounts made in this jig are not farmed out - I make them. My welding experience building dozens of mounts over 20 years translates into very high quality, technically correct mounts. Contact me for details on price and shipping.

Subj: Avid Mark IV
Date: 10/3/02

Have your Conversion Manual. I am thinking about building an Avid Mark IV. No one to my knowledge has used Corvair power on a Mark IV. Do you think the Corvair engine would be satisfactory? I want to build an aircraft with folding wings. Can we make this work? Which aircraft with folding wings are using your engine?

Reply from WW:
I am not sure if an Avid Mark IV is constructed with the weight of a Corvair or O-200 in mind. I've been told that the Mark IV is significantly heavier built than the original B and C models. If the factory approved it for a C-85 or O-200, then it can handle the weight of a Corvair. I believe several were flown with Subaru EA-81s with reductions, and we have proven that an EA-81 with a reduction is a heavier installation than a direct drive Corvair.
The Fisher Horizon is the only aircraft with folding wings that I know of flying with a Corvair motor. However, most designs of aircraft have quick detachable wings. There are several Sonerais flying with Corvair motors, and the wings detach fairly quickly. Pietenpols also have wings that can be detached quickly.

Subj: Front Starter
Date: 10/2/02

I have decided to go with the front starter on my Zenair 601. What year Nissan Sentra ring gear do you use? What is the thickness and diameter of the puck? Is there a drawing available? Do you need longer hybrid studs when using a puck?

Reply from WW:
The studs and safety shaft are sized for the front starter; they need to be trimmed for the rear starter. I am about 15 days away from having pucks in my hands. The same person who makes my hubs does them. There has never been a drawing as everything is in computer code. I will make a good drawing from one when the pucks arrive. I have made notes for people, but the front starter is becoming very popular again. I will have good drawings for it, have every piece available for it, and also have done kits available. I am very close to having all this in the bag. All of the front starter setups I made before had hand-built brackets, and all the new stuff will be CNC hydrocut. I will get you the exact part numbers and drawings soon. I have to build six complete setups for customers, so the information will be coming shortly.

Subj: Motor drawings
Date: 10/1/02

Is there any source of drawings of the motor? I'm designing my own airplane, and scale drawings of the engine would be really useful for laying out the firewall forward.

Reply from WW:
We recently received an incredibly beautiful set of scale CAD drawings of the motor from Manual owner Dan Benson. Dan is an engineer from Texas, and his drawings are nothing short of art. I've decided to put these in the Fall issue of the Corvair Flyer. The line work is so crisp that it should Xerox well and be a big help to you in your layout work.

Subj: Texas Event
Date: 9/30/02

I heard rumor that you were taking the Corvair College on the road for a weekend in Texas. How do I find out more about this?

Reply from WW:
This is true. There are a huge number of Corvair guys in Texas, many of whom are near the San Antonio area. We've picked the weekend of October 26, 2002. This week it's in the planning stage and we'll release more information next week. The basic plan is to have a one-weekend Mini College. I'll drive out with parts and tooling, and help Manual owners work on engines. Bookmark this page for future announcements.

Subj: Sonerai II with Corvair
Date: 9/29/02

I have been thinking about building the stretched Sonerai II LS. After looking at it some, and from what I can gather up from the Internet, it is marginal performance with two people. We are also big people weighing in at 221 and 150. I was wondering if you have seen someone hang a Corvair on one of these and if so how about the performance and your opinion on the whole thing.

Reply from WW:
Although the Sonerai's a good design, it is nowhere near big enough for people of your size. John Monnett designed it when he weighed about 140lbs., and he's 5-foot-6. Keep looking around. There are a number of other good designs which can carry two people your size on a 100hp Corvair motor. The EAA AeroCrafter manual is a good place to look.

Subj: Which carb?
Date: 9/28/02

I was getting to the part in the Manual about carbs and was intrigued by the Aero-Carb. I read your account of the testing you did on the 35mm Aero-Carb. Sounded good to me, but then you suggested getting the 32mm version. Did you test that one? On a 164 trying to get 110 HP, don't you need the 35mm? And then which one? Can you set me straight?

Reply from WW:
I am getting a lot of flight feedback from Glen David, who is flying a 35mm Aerocarb in a Sonerai II-Corvair. The carb you want is the 32mm flange mount. For a number of reasons, the Corvair will produce a lot of power on a small carb. When you have more cylinders and a large intake manifold volume, the carb size requirement is smaller than you might first guess.

Subj: Prop for Corvair-powered Avid Flyer
Date: 9/27/02

I have a 3-blade Warp Drive prop, 70", that I hoped would be usable with the Corvair. My installation is an Avid Flyer, maybe 100 - 110mph top speed. Do you think this prop is good for that? I noticed you used a 2 blade 68" in your plane. What if I went with just 2 blades on my 70"?

Reply from WW:
On an Avid I would use a two blade. Start with 70" and trim to suit your needs after flight testing. Do not use tapered tips on a plane in this speed range. Your speed goals will be easily met by this engine-prop combination. The Avid is a small, light plane and it will be a rocket with a Corvair motor. The Corvair should only be used on the Mark IV with a 1,250 pound gross weight. The early B and C models are too lightly built for four-stroke powerplants.

Subj: Head bolt nuts
Date: 9/26/02

I have obtained the GM Corvair shop manual and How to Keep Your Corvair Alive by Richard Finch so am now ready to begin my engine conversion. I have begun to disassemble the engine and am up to removing the head bolt nuts. Sure enough, the top head bolt nuts want to be difficult. I have followed Richard Finch's procedure but still some of the top had bolts (studs) want to unscrew from the block instead of the nuts unscrewing. The nuts do loosen but only come so far before the stud starts to turn in the block. Richard says not to let the stud turn in the block but I wonder what are the implications if I unscrew the stud from the block and reinstall after I remove the stuborn nuts? (To remove the nut after the stud is removed from the block, I would double nut the block end of the stud to hold the stud from turning and then remove the nut from the head end.) Should I leave the studs in the block and cut the stuborn nuts with a chisel to remove them (as Richard suggests) rather than loosing the studs more than about 1/4 turn which is the amount they turned before I noticed when I tried to undo the nuts. How can you tell whether the studs have been "pulled"? All of my studs seem to be tight in the block and loosen in the block only after a noticeable "snap" when trying to turn the head nut.

Reply from WW:
I would split the head nuts with a chisel and then unscrew them. A product called Kroil, which is an aerosol spray, has the best track record of loosening rusted nuts. If the stud unscrews and comes out clean, it probably did not pull out the thread in the case. If the ends of your studs are rusted, do not worry. The pads on the head, which the nuts rest on, can be milled down 1/8" to let the nuts work on fresh threads. Tighten the nut just until it moves (it lets out a ping) and then loosen it. If the nuts themselves are rusted, beat on a 13mm 12 point socket. Keep the lower studs tight to take the pressure off the upper row. Let us know how this works.

Subj: Which year engine?
Date: 9/25/02

I have a corvair engine # ta o504Z with 4 carbs. What year is it? If I put 110 heads on it, is the rest the same as the 164 engine?

Reply from WW:
A motor with a Z suffix could be a 1964 95hp (good) or a 1960-63 80hp (bad). If you take the top cover off and look at the crank, it should have the number 8409 cast into it in 1/2" tall letters (good). The four carb heads most likely indicate that this is a 1964 motor with 1965-69 140 heads and 65-69 barrels. There is a possibility, however, that it is a short stroke engine. The final determination is the crank.

Subj: Corvair powered Cessna 150
Date: 9/24/02

I've been thinking of purchasing a basket case Cessna 150 less the O-200. A Corvair engine just sounds absolutely perfect for the application! I have heard people mention the 110HP engine, but in my search for the engine, is there a specific year Corvair engine or block number or anything that I should look for? Also, what are your thoughts on slapping a Corvair engine on the nose of a 150? Finally, and thanks for your patience, what performance improvements can one make to the Corvair engine to increase the performance of the 0-200? I have flown 150/150s; 150 horses give the Cessna 150 plenty of get up and go. Can I get 150 horses out of a Corvair engine and maintain a bulletproof engine?

Reply from WW:
You're quite right that a 150 could be very smoothly powered by a Corvair motor. There are a number of modifications which could be made to increase the power output of the motor. Corvairs have been geared, turboed and overbored to 20% displacement increase. Much of this is covered in the Conversion Manual, available for purchase at the Online Catalog of Parts Available from The Corvair Authority . You could do all of these things, and people have and flown them. This gets a little bit away from the main benefits of the engine: simplicity and economy.
The first step in putting a Corvair in a 150 is to contact your local FSDO and find out how they feel about it. Your area officials have a very liberal reputation, but I'd check with them first. In our area, you must have a legitimate commercial program to engage in this type of installation. Once you have approval in your area, the Conversion Manual contains all the information on acquiring the correct engine, etc.

Subj: Cylinders
Date: 9/23/02

I recovered 3 Corvair cylinders, but I had to heat them on a plumber's furnace to get the pistons out. Not red hot. Do you think they are still usable?

Reply from WW:
I don't think you'll have any problems with the cylinders. The cylinder would not be harmed by heating it to 600F, as long as you did not cool it with water or cold air. When you bore out your cylinders, the machinist will be able to tell instantly if the cylinder is significantly out of round, but this almost never happens on a Corvair.

Subj: Zenair 601
Date: 9/22/02

I heard that you're working on a FWF for the Zodiac 601. I'm building a 601HDS and would be interested in your FWF. Can you give me details?

Reply from WW:
Here's the story of what we're up to on the 601. I'd appreciate it if you'd share this with other 601 guys. At Sun 'N Fun 2002, we met with the Heinz family briefly and explained the Corvair program to them. After some discussion, the Corvair motor was determined to meet the performance requirements while not exceeding the weight limitations of the 601 series. I'd like to emphasize to everyone that this was an engineering discussion, not an endorsement ploy. Sebastian merely agreed that the parameters of the Corvair as I presented them met the airframe requirements. I personally think it's a great match, and that's why I'm putting the work into developing the installation. When complete, we'll let the performance of the combination speak for itself. As I did with the Pietenpol, the KR and the Dragonfly before, I will be investigating and testing all the components that go into a good installation. In the case of the 601, this will be an easier process than the previous airframes. The reason for this is simple: the 601 being a highly standardized metal aircraft will have far less variation among airframes. This will result in a much easier standardization of components like motor mounts, intakes and exhausts. Additionally, after going through this process on other airframes, I can bring all my previous experience to bear on this one. My goal is the same as my previous efforts: provide a proven example to follow of a safe, economical installation. I will provide photos and drawings for people who want to plans build, and components for people who are more comfortable buying them. If there is enough interest, I would consider doing complete firewall forward packages for the 601. I have not previously done this on other airframes, primarily because those airframes had large plane to plane variations that would make this difficult, and the plans built nature of other airframes tended to appeal to guys who might be financially restricted from buying a complete firewall forward package all at once. The 601, being a kit plane in addition to a plans built airframe, makes it different on both accounts. This approach of offering plans, parts and perhaps FWF packages benefits all types of 601 builders. Some guys are working from plans and would just like to see how we do it, others may just want to buy parts like a mount and manifolds, choosing to build their motor from my Conversion Manual. If we go the full route and do the package with an overhauled motor, the simplicity and smoothness of the Corvair will be an option for people who are in a position to buy the package. Many alternative engine suppliers just want to sell the motor and leave the difficult installation issues to the users. Others just want to sell the complete package, which leaves out people without a lot of money. I want to work with everyone. As I said at my forums at Oshkosh this year, being the expert on the least expensive engine allows me to deal with everybody as a person. Contrast this with guys in booths trying to sell $12,000 engines. They meet you and in 30 seconds, if you don't look and sound like a thick wallet, they cannot afford the time to answer your questions. The 42-year flying history of the Corvair and my hundreds of hours of flight time on the motor mean that we're adapting a proven engine to an elegantly simple airframe. Please follow our Web site, flycorvair.com, for progress on this.

Subj: Thomasville, Georgia, Fly-In
Date: 9/21/02

Are you planning to attend the Thomasville Fly-In Oct. 11-13?

Reply from WW:
We have been invited to speak about Corvairs on Saturday at the Thomasville, GA, fly in. This FSAACA event has been a tradition more than 30 years. The old fashioned grass roots fly-in Draws about 500 aircraft. It is in southwestern GA. For more Info: call the Thomasville FBO at 229-226-8356, visit thomasvilleflyin.com "Join the tradition in 2002 for a fun-filled, family-oriented aviation spectacular unlike any other!" Gary Coppen will fly his Corvair-powered Skycoupe there and we will have Merrill Isaacson's motor on the test stand. Hope to see some of you there.

Subj: Distributor bushings
Date: 9/20/02

Is it necessary to use a dual bushing distributor to have a reliable ignition system?

Reply from WW:
While I've flown a lot of hours on single bushing factory distributors, the dual bushing modification offers improvement worth having. While I've offered recurving and dual points plates for several years, I've recently acquired equipment to put the dual bushings in the housings. Shortly, I'll be able to offer complete distributors with this modification, recurved, with the dual points plate installed, etc. The dual points system is perfected and flight tested over hundreds of hours. While I've recurved dozens of distributors, and sold more than 100 points plates, the best way for builders to match the reliable performance I've gotten is to let us do the work and test it in our distributor machine. Watch our Products Page for more information on pricing.

Subj: Corvair Flyer
Date: 9/19/02

I want to subscribe to the new Corvair Flyer. At Oshkosh, you said it would be at least four issues a year. Will it be available on the Web?

Reply from WW:
We're preparing the Fall issue of the Corvair Flyer. If your snail mail address has changed since you bought your Conversion Manual, please let us know. A yearly subscription costs $20 for the U.S. and $25 for international delivery, including Canada. You can order from the Online Catalog or just send a check. We will not be putting the Flyer on the Web. I personally like printed documents, and the Corvair Flyer is of such quality that I expect people to keep it as a continuing reference on the conversion of their chosen motor. To stimulate subscriptions, I'll use the Flyer to sell sale items and share information about sources of core motors which will appear nowhere else. We've all experienced the bickering of Web discussion groups and their useless chatter. The Corvair Flyer provides the ultimate solution to keeping everyone abreast of what's going on without the ills of the Web.

Subj: Stock fuel pump
Date: 9/18/02

Are stock fuel pumps in Corvairs reliable enough to use in aircraft?

Reply from WW:
In my 100,000+ miles of driving Corvairs, I've only had one fuel pump fail and it was a 25-year-old original factory installed pump. It failed very slowly over a period of thousands of miles. I personally like mechanical fuel pumps in airplanes. The entire story on fuel systems, from gas caps to carburetors, pumps included, is examined in detail in the new Conversion Manual.

Subj: GN-1
Date: 9/17/02

Quick question! Do you recomend one of your engines in a GN-1 application? Just bought a project that I thought was a Pietenpol and it turned out to be a GN-1.

Reply from WW:
The Corvair will power a GN-1 as well as it does a Pietenpol. John Grega designed the GN-1 and included the sentence in his plans discouraging the use of the Corvair. This was written about 1970, long before my developmental work and I'm not sure Grega ever saw a Corvair motor run anyway. Have no worries, it will do a great job.

Subj: 4-carb Corvair
Date: 9/16/02

I have a Corvair engine with four carburetor intake that I would like to use to replace my two-cycle 618 Rotax on my Merlin. Is this a good combination?

Reply from WW:
Four carburetor Corvair motors are known as 140hp motors. They make this power at a very high rpm (5,000), and are not desirable for use as direct drive motors. Myself and a number of other people have flown 140 heads and seen a big improvement when switching to a 110 based motor. Two additional concerns with a 140 motor are: It is prone to dropping valve seats, and 140s, which were used in automatic transmission cars, have a crank gear which advances the cam timing.
The Conversion Manual explains in great detail how to find a 95 or 110 motor and why these motors are much more desirable than the rare 140.

Subj: Retarded cam
Date: 9/15/02

I have a late model 65-69 engine that I assume had an automatic as the bell housing has large holes, presumably to cool the torque converter. In your book you mentioned that there were some made with the cam retarded by shifting the key slot on the crank. How can one ID?

Reply from WW:
You're correct: The big holes in the bell housing are for cooling the torque converter. Most automatics were bolted to 110s or 95s, and these have normal crank gears. Only the 140 automatic combination has the special gear. The best way to ID these is to use the pictures in the booklet "The Corvair Junkyard Primer" available from Clark's Corvairs for about 5 bucks. Please note that these gears are only on the very rare 140hp automatic engine. Standard automatic engines had perfectly fine, normal, crank gears. If your motor was a 110 or 95, chances are you have nothing to worry about.

Subj: Lifters
Date: 9/14/02

I followed your instructions on not soaking the lifters in oil before they were installed, but I cannot push down on the rocker arm and get the lifter to move. Are some lifters shipped with oil inside?

Reply from WW:
I've never seen lifters shipped with oil. All you have to do is assemble the motor and adjust the lifters so that they have a slight amount of slack. Then rotate the motor through about 10 revolutions. Doing this will loosen the plungers inside the lifters. Then they'll have smooth, free action. Then go back and put 3/4 of a turn of pre-load as I recommend in the Conversion Manual. When I assemble an engine in my shop, I stand it on the prop hub and bolt the hub to the table. By rotating the case with the table holding the crank still, you can easily turn the motor over to any position you like. This is the way certified engines are built up.

Subj: Corvairs and Wag-A-Bonds
Date: 9/13/02

Was re-reading the article about you in the NOV '01 Kitplanes and was thinking about Corvair installation in a Wag-Aero Wag-A-Bond (at 100-110 hp this would be adequate) or possibly the supercharged vesion (at 145-165 hp this would be adequate) in the 4 place Sportsman 2+2. Any comments?

By the way, the article mentioned an accident - have you recovered okay and what is known about the causes?
Reply from WW:
Thank you for your concern about my accident. The entire story is on my Web site at FlyCorvair.com Carb Ice: Don't let it happen to you. Other than a lot of scars, I've recovered completely. This was due in no small part to the encouragement of fellow homebuilders and aviators from all over, just like yourself.
A Wag-A-Bond is a great airplane for the standard Corvair conversion. We have several people working on them right now, but I'm reasonably sure the first to fly will be our friend Dave Vargesko. His airplane will be at Sun 'N Fun, which sounds like a long way off, but it's only 7 months away now. He still has to cover the airplane.
The 2+2 is out of the Corvair's league. Although I'm sure it would fly on motors as small as an O-290, most of these people feel that the airplane does best with an O-320 and up. While turboed and geared Corvairs have been built, they cannot match the simplicity of an O-320 in achieving 160hp.

Subj: Corvair for Fly Baby
Date: 9/12/02

I was wondering if anyone you know of has put a Corvair engine on a Fly Baby?

Reply from WW:
Although I know of none flying, we have at least 20 people building Fly Babies with the intention of using Corvair power, including two people who are building two-seat Fly Babies. The Fly Baby is a very good, traditional aircraft design, which Peter Bowers worked to make as simple as possible. The Corvair motor, with its inexpensive simplicity, complements the Fly Baby design.

Subj: Deep Sump Oil Pan
Date: 9/11/02

I am constructing my motor mount. I have the tray finished, with the dimensions from your Manual (#4550). Is there sufficient room for an aluminum deep sump oil pan?

Reply from WW:
Yes, there's plenty of room for the deep sump oil pan. I have a new batch in development and will post pictures on the Web site as soon as they're ready.

Subj: Front starter
Date: 9/10/02

I've followed all your work pioneering both front and rear starters. I've wavered back and forth a bit as to which I'd prefer. Do you have a list of pros and cons or a particular recommendation for my Zenair 601?

Reply from WW:
The new Conversion Manual contains the entire story on starter options. The front starter, which is where I first mounted it, has had a recent resurgence in popularity. Although slightly less aerodynamic, it is generally a simpler system that may well complement your 601. Additionally, the front starter allows the use of the stock mechanical fuel pump, which would easily draw fuel out of your wing tanks reliably. A complete comparison is available visually on our introductory video tape, showing two installations. We'll be further addressing this in the fall issue of the Corvair Flyer. Both are available from the Online Catalog.

Subj: Warp Drive propellers
Date: 9/9/02

Are you still selling Warp Drive props? I've followed your work with them on Corvair motors, and I've decided I want to put one on my Pietenpol.

Reply from WW:
I've been a Warp Drive prop dealer since 1997 or so. They make excellent products. They have a big line of propellers, but I just deal in the models appropriate for Corvair engines. We keep a few on hand in sizes that we have a lot of experience with for popular airplanes like the Pietenpol. Contact me for specific pricing information.

Subj: Flight time
Date: 9/8/02

I read in the latest issue of your Corvair Flyer that Tom Brown has flown for the past 19 years on the same set of points. Really? Do you mean the same brand of points or the same actual set?

Reply from WW:
This is true. Tom assured me that the last time he replaced the points was during his first annual many, many years ago. The low rpm of the motor and the light spring tension add up to very long life. Keep in mind this is not unusual. Tom has more than 1,000 hours on this set of points. All magnetos have points inside, and I know of numerous magnetos that have logged this amount of time without replacement also. People tend to forget how good points are.
For anyone who would like to subscribe to the newsletter, please send $20 for an annual subscription in the U.S., or $25USD for subscriptions to be mailed to Canada and other points around the world, to William Wynne, P.O. Box 290802, Port Orange, FL 32129-0802, or visit the Online Catalog.

Subj: Blue Max
Date: 9/7/02

Where can I find a set of the Blue Max coil wires you recommend?

Reply from WW:
If your local auto parts store doesn't stock them, Summit Racing, at 800-230-3030, sells the Moroso spiral wound universal fit with 90 degree spark plug boots.

Subj: Weight of prop
Date: 9/6/02

Was calculating bending moment on crank due to precession during maneuvers and P-factor. As it turns out, this imparts the same bending moment to the crank whether the extension is 1" or 100" long. Hard to believe, but precession results in "pure" couple and P-factor is a "pure" couple combined with axial load parallel and concentric to shaft. Weight of prop is important.

Reply from WW:
You obviously know your stuff about engineering. But in this case, you're wrong because of a missing detail, and if you tried to fly a prop with a 100" extension, you'd be dead wrong. You're quite correct that the force the prop generates doesn't care how far away it is from the engine. You could put the prop in the next county and it would still generate the same forces. However, and this is a crucial point, the lever arm that this force has to harm the crankshaft is the length of the extension. I come from a family of professional engineers. In this case, you've done your calculations right, you just missed the detail of the installation.

Subj: Engine selection
Date: 9/5/02

I was out following a lead on an engine but came up empty handed. However on the way home I stopped at a place and they have two cars and an engine but he didn't know what year they are. There must be an easier way than removing the shrouding to get the numbers off the head (I hope). Any help there?

It seems I remember reading somewhere in your literature that there never was a 4-cylinder Corvair, yet on a list I got from the local wreckers one of the dealers claimed to have one, a '65 out of a '62 car?
I am looking forward to working on my new project.
Reply from WW:
Anyone who tells you they have a 4-cylinder Corvair engine needs drug rehabilitation. To be fair, what he may be referring to is a 1965-66 motor with four carburetors. This is the rare "140" motor, which is a bad candidate for aircraft conversion (of course, it's a 6- cylinder motor also, just like the others). We generally don't check the head numbers if the motor has the correct block number. Removing the shrouds is the only way to check the heads, but on most engines, if the letter code on the block is correct, the heads will be also.

Subj: Re: Corvair PSRU?
Date: 9/4/02

Flying is a lifelong dream for me. I have always wanted to fly since I was a child but never had either the opportunity, or time, or money. After 22 years in the U.S. Army Special Forces, I find that I am now 41 and seeking my next career. I take with me this desire to fly one day. Money and time have always been a concern.

What I have been researching for years are the Canards. I am dead set on a four place. The widely accepted automotive alternative for canards are Mazda's 13 b engines. They require a PSRU or a transmission facsimile of a PSRU to make power in the range required. 13bs can end up running 5,000 or more depending on what all is done to make it airworthy. I know a lot about the 13 bs, but am HIGHLY interested in the Corvair since it has several advantages, "no water needed" being one of those.
The power range needed for a four place canard is 160-200/200+. Everything in my analytical brain tells me that the Corvair is a likely candidate but unproven in this power range or type aircraft. Any suggestions on this possibility is greatly appreciated.
Reply from WW:
Good to hear from you. I am 39 myself, and what I do now is the best job I have ever had. We have three other guys who we work with on Corvair motors who have day jobs in Special Warfare. I grew up in a military family and I am always glad to help out people who have done their time in the service.
There are not as many rotaries flying as most people think. There is sure a lot of interest, but there are only about 25 13bs in planes. I think the main reason for this is the fact that by the time you add it all up, the installation is generally as expensive as a Lycoming, and no auto conversion, not a Mazda nor a Corvair, is as reliable as a certified motor.
The charm of the Corvair is low cost, and the fact that my goal is to teach people to build it, not sell them one. Yes, a Corvair could be built to power a Cozy IV, but it would get to be a complex 10,000 dollar motor quick. Used 320 and 360 Lycomings are far cheaper than most people think. Go to your local A&P and ask him where the nearest repair station is. Go meet these people and ask questions and learn. There are a lot of people who push alternative engines and want people to think certified things are more expensive than they really are.

Subj: Corvair for a LongEZ
Date: 9/3/02

Great site. Lots of information. I wrote to you before on this issue, and I appreciate you taking the time to answer my question.

I'm building a LongEZ, normally powered by at least an O-235. Do you realistically think a Corvair engine could be strapped to a LongEz? In the plans, Rutan mentions using an O-200, but I've never seen one in a LongEZ. If the O-235 is producing a max of 118hp, could that be matched by the Corvair? Are there differences in the hp that the Corvair will produce at max rpm vs. the Lycoming at max rpm?
I am intrigued by the engine, mostly because of (hopefully) the simplicity of conversion (i.e., I am at the "idiots" level when it comes to engines). My other issue is that I am being transferred to Germany, and want a project directly related to my plane that can be done over there (I won't be shipping my fuselage overseas).... I am expecting to purchase an O-235 and rebuild it, but, again, a Corvair sounds like a cool plan.
Final issue: Since I know of no one who has a Corvair in a LongEZ, what kind of work is going to be required to get it on the plane itself? I am no rocket scientist, and I don't want to have to reinvent the wheel here. I am talking about engine mount issues, cooling issues, etc...
Thanks, and keep up the good work. I own an Ercoupe, and when the EZ is done, (years from now) I will be dreaming of installing a Corvair in my Ercoupe... But that's far in the future.
Reply from WW:
To be honest, I do not believe the Corvair is the motor for your LongEZ. Today in the shop, I'm welding up Arnold Holmes' Corvair to VariEze motor mount. This is a good match. The bigger EZ could be made to fly on a Corvair motor, but it certainly is not a first timer's project. You'd be much better off following the known path of the O-235.
When you're ready for an engine for your Ercoupe, give a call.

Subj: Corvair in a Nieuport 12
Date: 9/2/02

I'm thinking about a good powerplant for a Nieuport 12 (Graham Lee's design). I see you mention the plane on your engine specs page. The weight will be about right - but Graham recommends a redrive of 2:1 if using a Volkswagen, which I'm thinking has about the same powerband as the Corvair. I'd much prefer not using a redrive if possible - any thoughts?

Reply from WW:
The only Corvair which I know to have flown a 12 was a 145cid motor with a belt reduction. The belt was designed too tight and cracked the crank. Note, the plane still flew. This was all about six years ago in Michigan.
Your project will be much better off with a 164cid direct drive motor. The Corvair doesn't need a redrive to produce 350 to 400 pounds of thrust. There has never been a direct drive crank fail that I know of in 25,000+ flight hours. Direct drive motors built to my current specs are more powerful and lighter than EA-81s with redrives. Corvairs are stronger and longer lasting than VWs, and they cost far less to build, even when the VW is direct drive.
A modest direct drive Corvair flew my Pietenpol Aircamper to 105mph. This plane is as draggy as the 12, and I believe the Vne of the 12 is below this. The ready to fly weight of this motor was 230 lbs. with electric start, oil, etc. It cost about $2,500 to completely rebuild and convert using only the best parts.
I will be glad to help with the design of the mount or any other part of the installation. I am doing this to help people and make dreams happen. I have a long track record of being polite to anyone sitting on the sidelines, and also going out of my way to support the people actively working on their projects.

Subj: Front starter kit
Date: 9/1/02

I noticed on your Web site you once had a bolt on kit for front starter and alternator. Is it still availble? If so how much?

Leaning twards a Piet, Horizon 2 or a Ch701
Plan holder 5204
Reply from WW:
The front starter is returning to popularity. Originally, we worked with front starters only, but for the past two years, rear starters were the rage. I currently have seven or eight guys ready for front starter setups, and in an attempt to reduce the cost, I'm reworking the system to be made on CNC equipment. If you contact us in a couple weeks, I'll be able to give you a much better price on it.

Subj: Gyroplane
Date: 8/31/02

I have been building a gyroplane and intended to put a Lycoming O-290G in it. It is rated for 95hp at 2,200rpm. My design is limited to the use of a 52 inch fan or prop.

There may be an advantage to using the 3,500rpm of the Corvair to drive the same 52 inch fan or prop.
I saw the static thrust figure on your site using the temporary prop. Do you have any experience with the Corvair driving something closer to a 52 inch prop or fan?
Reply from WW:
With a small diameter propeller, you are correct in assuming that a high rpm is possible without sonic tip speeds. The good thing about using a direct drive Corvair motor in this application is the fact that the motor can be run at speeds like 3,500rpm continuously without hurting it. Compare for a moment a Corvair and an O-200 turning a 52" prop. At 2,750rpm, the O-200 will have reached its designed red line rpm. At 2,750rpm, the Corvair will be operating at its torque peak. As you add more rpm, the Continental will become overstressed, and horsepower will not increase significantly. On the other hand, the Corvair will produce significantly more power as it heads towards its horsepower peak (about 4,300rpm). And the Corvair will not be stressed as it's still below its red line of 5,500rpm.
The 54" props we have tested produced modest static thrust, because their pitch numbers in the 60-70" range are aimed at airplanes with 180mph cruise speeds. A purpose built 52" prop aimed at a gyro's cruise speed would produce very good thrust on a 3,500rpm Corvair.
An O-290 is a good engine, but it is significantly heavier than a Corvair, and it has a red line speed of 2,700rpm.

Subj: Corvair PSRU?
Date: 8/30/02

Has anyone thought of using a PSRU on a Corvair engine to get the horsepower up?

Reply from WW:
This has been done many times. The Corvair was the first motor ever to fly with a toothed belt reduction (Waldo Waterman, 1965). A few flew with the Rinker spur reduction (as seen on my Web site), and a friend of mine has a custom and planetary on his RV9.
But 95% of people need an inexpensive and reliable motor. The direct drive serves them much better. I have built and tested both types. The good track record of the Corvair is based on simplicity. If you are thinking of something specific, let me know. I might be able to offer some specific insight from experience.

Subj: Bell housing - rear cover - crankshaft
Date: 8/29/02

Got your manual/video and started disassembling the '65 110 engine I bought a couple weeks ago. I think you're very correct. It does in fact look like a fairly simple project. I have a couple questions.

1. Would a 1961 Van bellhousing/rear cover work on a '65 110 engine? ( I have found one for pretty cheap and I need one.)
2. I will be needing a crankshaft soon. I see that you sell them with safety shaft installed. I'll be ordering one within a week or two. I'd like to buy the crank and rod bearings, but am wondering what size to get. Are the cranks you send out requiring .010 bearings?
3. What's your opinion on roller rockers. I saw an anodized set of them on Mark L.'s site. Is it worth the extra few hundred bucks? I'm not looking for a super custom engine, but don't mind spending a little if something will really help.
Thanks so much for your time!!
Reply from WW:
The bellhousing is interchangeable. Don't pay much for it - I can sell you one with most of the excess cut off for 20 bucks.
All the cranks we send out are 10/10. Larry's in L.A. sells bearings cheap. The address is in the Manual.
Roller rockers are not required, and offer no performance boost to speak of.

Subj: Engine mount specs
Date: 8/28/02

I need to know the vertical distance from the engine mount spool washer faces to the CL of the crankshaft. Would also like to know make and P/N of urethane bushings recommended.

Reply from WW:
The vertical distance is 7". Eight bushings come in the standard Performance Sway Bar End Link Bushing Set from Energy Suspension, part number 9.8105RC.

Subj: Non-standard rotation
Date: 8/27/02

William, thanks for your quick reply.

One more question. I did build my Celebrity with a slight offset in the vertical fin to counter the P-factor of the engine. I set it for a standard rotation engine. To use the Corvair I either had to change the offset or the rotating direction of the Corvair. Your book tells me it can be done by using a different cam?! But how about the lube system, rotating direction of the lube pump, distributor, main bearings, etc. Going back to my engineering days, I remember that the location of the oil suppply bore in a hydrodynamical bearing is important. Now if you change the rotating direction you change the load zone in relation to the lube supply hole. Will it work? Is this a problem or am I making it up? Can I get the same cam that you prefer for right hand rotoation? What changes are needed to the distributor?
Reply from WW:
There's a great deal of experience with the Corvair motor being used in either rotation. The cam that we use is available in a reverse grind. However, it is twice as expensive, other internal modifications to the motor are required, and the starter must also be reversed. Many small issues, like the timing marks not being in the right place anymore, will need to be addressed. The basic oil system has proven to work perfectly in hundreds of reverse motors used in ground applications. My gut reaction is change the vertical fin; it will take a lot less time and money. The best way to operate the motor is following what we have already pioneered. Flying a reverse motor, while far from impossible, adds unnecessary challenges.

Subj: Re: Corvair Engine for a Woody's Pusher?
Date: 8/26/02

William, thanks for getting back to me. The Woody's Pusher uses a 65hp - 85hp Continental, but some have used a 100hp engine. I will be ordering the update from you. Thanks again.

Subj: Dyno
Date: 8/25/02

I thought about setting timing, valve clearance, etc., with a running motor. Have you thought about a home-built dyno of some kind? I've dreamt up, at least in my noggin, some kind of water-pump like machine, homebuilt of course, that could take 100hp. One would hook up the prop to this, fire up, and not have a big club running near one's body. Have you thought of this at all? Am I barking up the wrong tree?

Reply from WW:
As a licensed A&P, I have tuned many motors 6" from a running propeller. Many of my A&P colleagues are justifiably unnerved when work like this is required. The best situation, as you state, is to avoid it completely. By properly setting the lifters of your Corvair motor at overhaul, they will never again need to be adjusted for the life of the motor. This precludes having to work near the running propeller. Checking the timing must still be done with a running motor, but this is done from the relative safety of 30" behind the propeller. We've used dynos before, and there are pros and cons to different types. The method you mention is similar to an industry accepted dynomometer called a water break. Many industry dynomometers will not work with Corvair motors because they turn the other direction. The easiest method, and the one I use, is instantaneous torque measurement with horsepower calculated by rpm. This is very accurate, but it does require turning a propeller.

Subj: SAA Fly-In
Date: 8/24/02

Would it help you in any way were I to volunteer to bring a Corvair engine (in whatever state of operation I have it in, from just pulled out of the boneyard to ???) to SAA next year?

Reply from WW:
Thanks for your generous offer. Grace and I had a great time at SAA Fly-In #1 this year and will certainly be back next year. A time pinch forced us to fly in commercially, but I hope to have several Corvair-powered airplanes, including our own, there next year. As time gets closer, we'll make arrangements. I think a customer's engine in process is always an educational and inspirational opportunity for new guys.
For those of you unfamiliar with the Sport Aviation Association, it's a grass roots organization started by Paul H. Poberezny which caters to plans built aircraft and simple antiques and classics. Free of commercialism, their publication To Fly is available and is the direct method of communication among members. Their annual fly-in, which has the flavor of the earliest days of the EAA, is held in Urbana, Ill., in July.

Subj: Re: Fisher Celebrity
Date: 8/23/02

Thanks for your reply. It indeed can use an O-200. How about cooling the Corvair engine. Will a J-3 style cowling, free air cooling work? (I ordered your book via the Internet.)

Reply from WW:
The Corvair cools very well. I believe it will cool as well or better than the O-200.

Subj: Head threads
Date: 8/21/02

Is there a fix on the head for pulled threads for spark plugs? Would like to purchase a "drop-in" crank/hub/safety shaft. Availability?

Reply from WW:
The fix for the stripped plug thread is a timed sert or a heilicoil. The Clark's Corvair catalog has more info, and the whole catalog is online now.
We have cranks available. They are $324 plus your old core. These cranks are reground 10/10, threaded, and come with the six hybrid studs and a safety shaft.

Subj: Fisher Celebrity
Date: 8/20/02

I am building a Fisher Celebrity and am looking for about 100HP. Do you think your engine would work? I found you on the Web. Thanks for your input. Can you give me a Fisher reference?

Reply from WW:
I know the Celebrity, but I do not know the specifics on the engine limits. The best way to determine if the Corvair is a good match is to find out if the O-200 100hp is approved. The Corvair weighs the same.

Subj: Engines from Ebay
Date: 8/19/02

Do you have any recommendations on getting an engine? I see ads on Ebay, but I don't know if that is a good way to go. Alternately, if I go to a local salvage yard, are there things to look for when trying to find a reasonable engine?

Reply from WW:
The Manual covers finding an engine. The best way is word of mouth, asking around starting at the oldest auto parts store in your town. If you have a real hard time, let me know.

Subj: Corvair Engine for a Woody's Pusher?
Date: 8/18/02

Would you comment on using a Corvair engine conversion in the Woody's Pusher? I already have your Conversion Manual. Should I purchase your latest version? Thanks.

Reply from WW:
I have not seen the structure of a Woody Pusher, but I believe they were approved for O-200s, so the Corvair should work. The thrust bearing is double-sided, so it will work as a pusher.
The new series of Manuals began with #5000, which we sent to Andrew Pietenpol, Bernie's grandson. I highly suggest you purchase the updated version. The Manual now contains about twice as much information, along with photographs, drawings and graphs, in 125 pages.

Subj: Ragwing Stork
Date: 8/17/02

Hi. Will the corvair engine work in the Ragwing Stork or is it too much weight?

Reply from WW:
I do not know the Ragwing Stork well enough to answer this question. If the designer approves of an O-200, then a Corvair motor will work. If the O-200 is overweight, the Corvair will be also. Please let me know what the designer says.

Subj: Zenith 701
Date: 8/16/02

Will this aircraft take a Corvair conversion and be useful on floats, skis and wheels? I am building this aircraft from plans soon and am very impressed by what I have seen so far, but I am really new at all of this, first time for everything. Thanks for all of your efforts and research.

Reply from WW:
The 701 is supposed to have less than 200 pounds ahead of the firewall. Although the plane has been flown with motors which weigh more than the Corvair, the factory told me directly that they feel that the 230 pounds of a typical Corvair is a bit much for the light construction and design of this plane. However, they did approve of the Corvair for all of their 601 models.

Subj: WAR replica FW-190
Date: 8/15/02

Have you heard of anyone putting a Corvair Conversion in a WAR replica FW-190? The standard engine used is an O-200 Continental. I am in the process of purchasing a partially completed airframe and am wondering if the Corvair would be a suitable replacement.

I notice the fuel burn of the 120hp O-190 is nearly 8gph at 75%. Do you know what it is at WOT ?
Thank you for your time
Reply from WW:
The standard Corvair would be a good powerplant for your application. We've had numerous inquiries from WAR replica builders, but I don't know of anybody flying yet. The narrow 28" width of the Corvair helps with more realistic cowlings on replicas. The 190cid motor would certainly provide more power, but I believe the standard motor would power your aircraft very nicely. I base this belief on how well the motor works in similar size aircraft like KR2s.
Fuel burn for virtually all air-cooled aircraft motors is 1/2 a pound of fuel per hp per hour. Example for 100hp: .5 lbs. x 100 x 1 hour = 50lbs per hour /6 = 8.3 gph. Fuel injected and liquid cooled engines do only slightly better at .45 pounds.

Subj: Crankshaft threading
Date: 8/14/02

I would like to have my crankshaft threaded on my Corvair 164 cubic inch motor so I can install your safety shaft and mount your prop hub. I'm going to use the original factory running of the motor, so the prop will spin counterclockwise as seen from the pilot's seat. I'm also going to use a Warp Drive 3-blade propeller. To what address do I send my crankshaft? How do you want me to pay for it?

Reply from WW:
Payment by check is fine. You can send it along with your crankshaft UPS to the following address:
William Wynne
210-11 Cessna Blvd.
Daytona Beach, FL 32128
(386) 451-3676
Pack it very well. We've had one or two damaged in shipping. Threading the crank costs $60. The safety shaft is $66, studs are $66, and prop hubs are $299. Many people send us their crank as a core and buy our drop in 10/10 reground crank with the safety shaft and hybrid studs for $399. We refund $75 if your core is usable.

Subj: Corvairs in Pietenpols
Date: 8/13/02


My name is Ted Phillps. I am a recreational pilot and have decided to build a Pietenpol! This will be my first time building an airplane and other than being very excited about it, I'd be lying if I said I wasn't a little intimidated! I've done a lot of research on the Air Camper and it seems that the Model "A" engine is used a lot. I have some reservations about such an engine, but being a simpler powerplant, it seems I could work on it easier than I could a more complicated Corvair. Is my thinking right? Or would a Corvair be just as easy to convert? I'm sure you get a lot of e-mail, but I would really appreciate your thoughts on this whenever you have a spare moment.
Thank you for your time and the VERY educational Web site!
Reply from WW:
Thank you for a very nice, straightforward e-mail. While aircraft do demand your best workmanship, the project should not intimidate you. The Pietenpol is an excellent choice. Thousands of Piets have been built over the years. This is not coincidence. It's a good airplane with a great following of people and it's reasonably easy to build.
The Corvair does have more parts than a Model A. But still, the Corvair is a very simple powerplant and very easy to work on. While there are a number of people knowledgeable about A motors, the Corvair has the advantage of being my full-time business. In short, supporting people using Corvairs is my job, not something I do casually or part-time.
The Corvairs we build are much more powerful and smoother operating than any Model A motor could ever hope to be. We put electric start on virtually every motor, and operate them with the same degree of utility that you'd expect from a certified motor.

Subj: Bought a motor
Date: 8/12/02

Thanks for the advice..... After picking up the motor and doing a quick inspection of it, my dad and I got to talking and figured we should try it. The motor is in good shape and I only paid $150 for it. Back in the late '80s, we both rebuilt a Porsche 914 engine for our sandrail. We rebuilt it from the ground up. It took longer than what a shop may have done, but in the end we did save money and the motor ran great.

We got to thinking, why shouldn't we just do the same with the 'Vair engine. We're going to go for it. I will be placing an order for your Conversion Manual. I know that there are parts we will need such as cam, prop hub, intake manifold, etc.... I think I saw that you sell these parts right?? I'm in no rush to build the motor and if it takes me a year, then fine. The plane won't be ready until then anyhow. As we get further into this I'm sure I may need to contact you from time to time. I'm willing to pay you a few extra bucks for your advice if we need to call you. Hopefully that's something you can do.
Anyhow, thanks again!!
Reply from WW:
I liked your attitude in your last e-mail. This kind of spirit always gets a motor or an airframe done.
Of course we make prop hubs, manifolds, mounts, etc. As you get further along with your project, let us know how we can help you.

Subj: Howdy, from Tennessee
Date: 8/11/02

I bought Manual number 5203 from you in Oshkosh. I was the dude that asked if I could get my money back If I didn't feel like a Corvair engine would work out. I want to thank you for that option, but no, you aint gonna get your Manual back now! I will be sending your Liability Statement and Registration form soon. I am excited. I know it will take a long time for me to build this plane and engine, but at least I'm starting the steps to building my dream. I told my wife, it's kind of funny, I work for people who can afford a new Lexus but who don't know how to change oil; I can rebuild the Lexus but can't afford oil! Thanks for all you have done trying to keep aviation affordable.

One question: If I need a flex plate from a Nissan, can I use a Nissan starter? I have one I'm gonna take to the junkyard for scrap - it's a standard so I will probably just buy a new flex plate. If I can, and you think it's OK, I will use the Nissan alternator or one from a Geo Metro.
Reply from WW:
Good to hear from you. Thanks for the nice words.
The Nissan starter would turn the wrong way.

Subj: CHT
Date: 8/10/02

How cool should the cylinder heads run? What's a good range? What are typical temperatures?

Reply from WW:
Factory cylinder head redline is 575F. Many well-baffled installations will run 300F in cruise and 400F in a climb. These should be regarded as minimums. Engines running cooler than this are not as efficient and not at the temperature which GM designed the engine to operate at. Even 450-475F in a climb will provide a very large margin of cooling to the factory limits. This is a well designed motor. I know of no other air cooled motor which has such a high red line.

Subj: 100 low lead
Date: 8/9/02

What are our options if 100ll is eliminated? Does lower octane fuel require a change in timing?

Reply from WW:
I have driven Corvair automobiles more than 100,000 miles on unleaded fuel. I later disassembled these engines, inspected them and found no damage whatsoever. If 100ll goes away, we can operate Corvair motors on 93 octane gas with a 2 degree reduction in maximum ignition advance. I have several pages of commentary on my findings on various types of fuel in the new Conversion Manual.

Subj: Shock cooling
Date: 8/8/02

Do we need to be wary of shock cooling with the Corvair?

Reply from WW:
Shock cooling is not good for any type of engine, air or liquid cooled. Aircraft motors are susceptible to cylinder head damage when rapidly cooled. The Corvair motor, although an air cooled design, is far less prone to this type of damage. Its slightly heavier than average aircraft construction offers a resistance to shock damage which some certified engines don't have.
The issue of shock cooling largely applies to very fast, high flying, tightly cowled homebuilts. When this type of aircraft is forced to make a rapid descent in controlled airspace, it can damage the engine. This type of problem does not concern the vast majority of Corvair powered airframes.

Subj: Fuel pump
Date: 8/7/02

Can I use the stock fuel pump?

Reply from WW:
The stock Corvair mechanical fuel pump is a very reliable unit. When using a front starter motor the fuel pump may be retained in its standard position. With a rear starter motor, keeping the pump is more difficult. Many people use gravity feed or electric pumps with rear starters. The complete story on fuel issues is covered in depth in the new Manual.

Subj: Milling manifold
Date: 8/6/02

I wanted to mill the intake log off the cylinder head and weld up my own intake log with the intake on the end instead of the top. Is this a good idea?

Reply from WW:
A lot of people stumble over this idea, and a few have spent the time and money to try it. From their experience and my own, I can assure you that after all your time and trouble, you will likely end up with a motor with less power than the stock log. GM had some really great engineers, and the stock intake manifold is a tribute to their talent. Save yourself a lot of hassle and leave it in place.

Subj: Safety shaft
Date: 8/5/02

I would rather not thread the crank. A shrink fit on the safety shaft or no safety shaft at all appeals to me if that is determined to be safe.

Reply from WW:
Every motor that goes out of my shop gets a safety shaft. A handful of people are using a secondary method called the snap ring. Both of these are well outlined in the Conversion Manual. Testing revealed the shrink fit method to be inadequate. It is unacceptable under any circumstances to fly with no safety. In the past year, three or four motors built according to my specifications were sold amongst friends. Notably, one motor which did not have a safetyed crank, sold for $1,000 less because the new owner was going to take it apart and take care of this deficiency. Resale value should be the least of your concerns. No safety is a gamble with a high price tag not worth taking.

Subj: Exhaust
Date: 8/4/02

Is there any advantage or disadvantage to dual exhaust or using a Y-pipe and a single outlet?

Reply from WW:
Dual exhaust always seems easier to install. A Y-pipe and a single outlet will generally be quieter, but there will be no noticable difference in power.

Subj: Winter flying
Date: 8/3/02

I fly in the winter in Indiana, Michigan and Canada. How does the Corvair handle winter conditions? Has anyone put a Corvair engine in a Zenith 601HDS?

Reply from WW:
The Corvair motor, being an automotive engine, was designed to operate exclusively on multi-viscosity oils. We also have hundreds of flight hours of experience with synthetic oil and I highly recommend it. Multi-viscosity synthetic oil in an engine designed for it, coupled with modern, compact, high efficiency electric starters, adds up to engines which will easily start and not suffer damage in cold climates.
We recently had a report that a gentleman in Canada had flown two seasons with a Corvair motor in a 601. Although there are about 50 people working with my Conversion Manual to install a Corvair in their 601s, none are flying as yet. As related to me, the gentleman in Canada experienced some type of overheating. It is unfortunate we were not in contact with him. I have no problem getting the Corvair to cool in any of the installations I've covered. We were recently flying a draggy Skycoupe with a cowling similar to a 601. With proper baffling, this motor ran with a 275 degree CHT. This is actually too cool; 350F would provide more efficient operation. The Corvair's red line is 575F, and there's no reason why anyone should experience difficulty cooling the motor if proper technique as outlined in the Conversion Manual is used.

Subj: Prop size
Date: 8/2/02

I am building a 7/8 scale Nieuport. I have a VW 65hp engine, but would like to have the Corvair. I would like to have as large a prop as possible and believe the Corvair maybe would be able to run a larger prop. What's the upper limit?

Reply from WW:
A Corvair can turn a much larger propeller than a VW. Even when a Corvair spins the same diameter and pitch propeller as the VW, it will use perhaps twice as much blade area to absorb the greater power of the Corvair motor. A direct drive Corvair, built straight from the Conversion Manual, for about $2,500, will easily spin a 68x30 prop on your Nieuport. This prop will have a 4" thick hub, and 6" wide blades, and will be much larger than any propeller you've seen on a VW. Engines like this produce enough thrust to drive Pietenpols well over 100mph. It would probably do even better on a far lighter Nieuport.

Subj: Corvair for Emeraude
Date: 8/1/02

There are a number of Em's flying with O-200s, but a little more horsepower wouldn't hurt. What do you think about this?

Reply from WW:
An Emeraude is an efficient aircraft. The standard Corvair motor can match the performance of the O-200 at a fraction of the price and with twice the smoothness. If you are looking for slightly more power, you may want to consider the 190cid Corvair conversion. It is a hybrid of Corvair and VW parts. While it takes more work to build, and costs about $1,000 more, it provides a 26cid boost in displacement on bore alone, and due to machining, the motor actually weighs about 8lbs. less than the standard motor.

Subj: Engine choice
Date: 7/31/02

I have two Corvair engines available to me: one is from a '65 Corvair Monza and one from a 1961 Corvair work van. Any comments or observations on these two engines would be appreciated. I have a Zenith 601HD in progress and one or the other of these engines would be my choice. I would appreciate your thoughts regarding this also.

Reply from WW:
In short, the 1965 engine is a viable candidate, and the 1961 is only good for miscellaneous parts. The complete story on the selection of engines is contained in the Conversion Manual, including casting numbers, date codes and evaluation criteria. Your '65 engine will make an excellent conversion powerplant for your 601.

Subj: Overlapping power strokes and wooden props
Date: 7/30/02

There is one advantage you should mention in your book about the use of a 6-cylinder engine: Overlapping power strokes. No 4-cylinder engine has overlapping power strokes. Overlapping power strokes are very important if a wood propeller is used. I would never use a wood prop on a 4-cylinder engine of more than 90hp. When there are heavy, individual power strokes being put into the crankshaft, and thus into the hub of the prop, something has to give. If the bolts are not torqued enough, the bolt holes in the prop can become elongated.

Probably you have not encountered any problem in using a wooden prop on Corvair engines. What type of wood prop have you been using? What pitch and diameter?
Reply from WW:
You are quite correct that the overlapping power strokes of a 6-cylinder engine are a big advantage. This inherent smoothness goes a long way beyond propeller installations. Things which typically vibrate and crack all over 4-cylinder installations and 90 degree V-6s are vibration free and crack free on Corvair motors. This extends to exhaust pipes, accessory brackets, baffling, etc.
We've used a variety of wood props on Corvair motors. A very successful prop on Pietenpols is the 66x32. But remember, the Corvair motor makes a lot of torque and it will need far more blade area than other motors using props with the same diameter and pitch. Ask your propmaker; he'll know his own work best.
Historical note: There have been a lot of successful wood prop installations on 150-200hp 4-cylinder engines. But you're right - they require far more attention to detail and maintenance than 6-cylinder engines.

Subj: Installing Corvair in a Pietenpol
Date: 7/29/02

I am building a Sky Scout Pietenpol. Does your engine mount as though you were installing a regular airplane engine, to the firewall? Also, you've said you did not have down thrust on your mount and you raised the thrust line 4" - why?

Reply from WW:
If you're building a Sky Scout, and planning on using a Corvair instead of a Ford, I highly suggest you study the Air Camper drawings for the long fuselage and the Corvair motor mount. This style of mounting and fuselage attachment would be my recommendation.
Almost all traditional looking airplanes had the thrust line in line with the top longeron. You can study a lot of parasols, biplanes and even most monoplanes and see this to be true. This was the thrust line I used for my Pietenpol. I believe it greatly improved the look of the airplane, provided more space for the carburetor and air box below the engine, and allowed greater ground clearance to the propeller. It did not noticably affect the handling of the plane.
I believe the Pietenpol's low thrust line was simply to gain the best fit with the Ford motor. Bernie Pietenpol kept this thrust line with his Corvair installations because he retained the stock blower fan, which sticks up several inches above the motor. Our electric start motors do not use the blower fan, and can be mounted higher in the airframe.

Subj: Corvair & Tailwind
Date: 7/28/02

I plan to build a Tailwind airplane and don't quite understand if various length props affect the maximum rpm they can revolve at. I read somewhere the rpm of props cannot exceed 2,800rpm, but I've seen mention of achieving 3,000rpm using direct drive. If you have any information on the subject, I'd be interested in reading it.

Reply from WW:
The new Conversion Manual contains formulas and graphs to illustrate the maximum allowable propeller diameter. The limit is based on the true tip speed. True tip speed is dependent on two factors: the rotating component, which is the result of the diameter and the rpm, and the speed due to the aircraft's forward velocity. A branch of mathematics called vector addition is used to calculate the true tip speed. The graph in the Manual spares you from this, and a geometric calculation is also included. Sounds technical, but it's real easy to see with the paper in front of you.
You're quite correct that there is no hard limit for propeller rpm. The person who told you props can't exceed 2,800rpm doesn't know what they're talking about. Many props can operate far above this with very good efficiency.

Subj: Sport Plane for Corvair
Date: 7/27/02

While I really like the Zenith 701, I'm not nuts about spending $10,000 for an engine. If the Corvair is not a good fit for the 701, are there others that can take that engine and stay within the new "Sport Plane" parameters - 1,232 gross, 45mph landing speed?

Reply from WW:
There are many, many designs which could meet the new Sport Plane requirements when powered by a Corvair motor. Two diverse examples would be the Zenair 601 and a Wag-Aero Wagabond. There are all manner of high and low wing airplanes, plans built and kits, which can meet the Sport Plane category and still have a good useful load when powered by a Corvair motor.

Subj: Paint
Date: 7/26/02

Can the Corvair engine be painted? Which parts should I be extra careful not to paint? I'm thinking of lime green, by the way.

Reply from WW:
You can paint the Corvair any color you like. On motors we build, I usually paint only the steel parts: cylinder barrels, valve covers and pushrod tubes. The pushrod tubes should be painted gloss white for heat control reasons outlined in the Manual. On our motors, the cases, heads, pans and end covers, all of which are aluminum, are left bare. There is no significant cooling difference if they are painted or not.

Subj: Fix for hard starting
Date: 7/25/02

I'm building a Pietenpol and have it up on wheels with ribs finished. Ten years ago I helped overhaul an engine in a '65 or '66 Corvair car. We put in new bearings and rings and we hand ground the valves. When we started it, it was very low on compression and I think the carburetor needed to be opened over and over to pump it to keep it running. Do you think the tappets could be guilty? It started very hard. If you can give me any suggestions, I'd appreciate it.

Reply from WW:
My suspicion on why it would run poorly would be primarily ignition or carburetion. Let me carefully advise you against flying re-ringed motors. In a V-8, to replace the rings, the wear ridge must be taken off the top of the bore. Conversely, in a Corvair, this wear ridge can be left in place and new rings can be installed in an old bore with the wear ridge from the bottom. In flight, you will use more power for a far longer period than a car ever would. When the pistons fully come up to temperature and expand, the square edge of the new top ring will contact the wear ridge in the bore. In a few minutes of sustained high power operation, the head of a stock cast piston will come off and your glider training will begin.
The simple way to avoid this is to use bored cylinders, forged pistons and new rings. If you absolutely must use stock cast pistons, which I do not recommend, the wear ridge at the top of the cylinder must be removed.

Subj: '63 motors
Date: 7/24/02

I have an abundance of '63 motors. I noticed that you mentioned that these were "no good." Would they be suitable candidates if I used the 164 crank? I'm thinking of an Air Camper application. Another thing is that Bernie Pietenpol was said to have flown a 1960 motor. This would have been a 140 cubic inch model. I would appreciate any insight to help clear up my confusion.

Reply from WW:
You're quite correct. Bernie did first fly a 140cid motor. By 1966, he had flown the 164cid motor and felt this was a much better choice. Today, we can get substantially more power out of the Corvair motor than Bernie ever flew with. This is the result of 30 years of progress and my relentless R&D in the past 10 years.
The 1963 case will not hold a long stroke crank without significant clearancing. If you're willing to spend the time with a die grinder, I've seen it done. However, it should be noted that the combustion chamber size and the new stroke will yield a compression ratio in excess of 9:1. In the end, it's just easier to get a 164cid motor to start with.

Subj: Tractor gyro
Date: 7/23/02

Thanks for the reply. I know about different measures for thrust. I have three good cases and one set of 95 HP 1964 low compression heads and the other set of heads I will find out tonight what they are. I am placing my order for the Manual today but need to talk to you before I order some other stuff. Mike Lindsay is going to put his Corvair on a tractor gyro too. I will be making the prototype and he will follow.

Reply from WW:
Good to hear that you hooked up with Mike Lindsay. He's one of our favorite people. Be glad to lend our support to the project in any way that we can. Tractor gyros have long been an interest of mine.

Subj: Graham Lee CIRCA Nieuport 12 question...
Date: 7/22/02

Hello William. I just ordered your book and video. I have a question. I was building a Pietenpol Air Camper but have put that on hold. I am going to build the Nieuport 12. I asked Graham if a Corvair engine would work and he said yes, they had been used, but would need reduction.

Do you know why this is? I want to use a wood prop. Is that why? Needs to turn slower? Thanks for any insight. I hope to make next year's Corvair College with an engine in tow. I have SO MUCH to learn. ;) It's great!
Reply from WW:
I don't think Graham knows very much about Corvair motors. Several years ago, a friend of mine flew a Corvair in a Nieuport 12. He had a reduction, but the reduction did cause him some problems. Notably, he was using an early model Corvair, which we do not recommend. Currently, our direct drive Corvair conversions can match the performance of an O-200 Continental. Corvairs make more power and thrust than most of the engines which have been flown on the model 12. You can use either wood or Warp Drive props on a Corvair motor; it works equally well with both.

Subj: Oil pan
Date: 7/21/02

How much weight does the custom oil pan save? Off the hand-propped version?

Reply from WW:
The custom oil pan weighs the same as the stock oil pan, but has two more quarts capacity.

Subj: New cylinders?
Date: 7/20/02

What is your opinion on the new cylinders that are being developed for the Corvair?? With your vast experience, would you even consider this an improvement, or have they yet to be proven?

One more thing. Sure would like to contact anyone building a VP2 (Volksplane) and installing a Corvair!! Have to solve the weight and balance issue.
This Q and A area is excellent. Thanks, and keep up the good work.
Reply from WW:
We're going to visit Dale Jorgensen in the next week. He's the high time Corvair powered VP-2 pilot. E-mail me your phone number and address, and I'll extend it to Dale. I don't believe he's online.
Let me assure you the Corvair does not need lightweight cylinders to work well in a VP-2. All I've heard is talk of cylinders. They're quoted at more than $1,000 a set, and more importantly, have never been made to run on a Corvair. In a position of responsibility, it's impossible for me to endorse something that no one's ever flown.

Subj: Welding rod
Date: 7/19/02

Is there a special welding rod used to make aircraft motor mounts? Would you use a different rod with a TIG welder?

Reply from WW:
The new Conversion Manual contains an entire chapter on how to build Corvair engine mounts. This contains detailed information on methods, materials, jigging, etc., along with numerous drawings and photos. I recommend gas welding and mild steel rod for mounts. A number of skilled welders use stainless rod on 4130 when TIG welding. There is some debate about copper coated rod, but with proper technique, I've never seen it contaminate a weld. The whole story is in the Manual.

Subj: Corvair engine choice
Date: 7/18/02

I have access to several Covair engines. Is there one particular model which is better for conversion? Both the 164cid and the 190cid are available. This engine will be used to power a Pober Jr. Ace.
Reply from WW: We have several people builidng Corvair-powered Jr. Aces, and one model beginning its flight test work. At least one person several years ago flew a very modest conversion on an overweight Jr. Ace. All of the guys currently working on this will end up 200-240lbs. lighter with at least 25 more hp. The model of engine we most commonly use is the 164cid 1964-69 model. All the serial numbers of the acceptable models and how to identify them are in my Conversion Manual. I strongly doubt that you have seen a 190cid motor. These are hybrids made by adapting VW cylinders onto a Corvair. They were never made by GM, and only 12 have ever been produced for aircraft. Much more information about the 190cid is also in the Conversion Manual, available through the Online Catalog.

Subj: Wrist pin height
Date: 7/17/02

I am assuming that because of the difference in stroke between the 102 and the 110hp crank that the deck height of the piston must differ. Is this correct as the rod and cylinder are the same?

Reply from WW:
Yes. Early motors have a greater distance from wrist pin to piston top. Keep in mind my firm recommendation that people convert 1964-69 motors only.

Subj: RA motor
Date: 7/16/02

I have obtained a Corvair engine with the last two letters of the serial number being RA. One of the Corvair books I have says this is a 95HP low compression engine. I plan on only using the block and replacing everything else. The engine has set outdoors behind a garage for at least a year. Can this be setup as a 110HP engine? I keep getting conflicting information. The guy I bought it from swears it is a 110HP engine or was overhauled that way.

Reply from WW:
Any case that starts with the letter R will make a good flight motor. Check the serial numbers on the heads and do not assume that they were the original ones for the motor. The approved cylinder head list is in the Conversion Manual. If you actually have open chambered heads, any correct head can be used to replace them. 95 or 110hp as a core does not matter; the differences between the motors were cams, ignition timing and carb jetting. We replace all of these when we do the conversion. Either engine would produce the same power when converted according to my Manual.

Subj: Kitfox
Date: 7/15/02

I've come across a Kitfox VI, and would like to know if the Corvair is suited for it.

Reply from WW:
The Corvair will work well on any of the newer Kitfoxes, models V and higher. The earlier models are too lightly built to handle engines like the Corvair or the O-200. A model VI would be a great airplane for the Corvair. A note to people looking at model IVs: Although people put heavy installations, like belt reduction EA-81 Subarus, on these planes, it's really outside the limits that they were designed for. Thus, I recommend only models V and up for the Corvair.

Subj: Ordering
Date: 7/13/02

Hi William: I have to order the prop hub and hybrid studs.I would also like to order your new Manual, but I need its price.

Reply from WW:
We are currently on a big tour of the eastern U.S. with our final stops at Oshkosh before returning to Florida. When we're on the road, we bring a lot of items to fill orders with. Anything ordered through PayPal is shipped at the first opportunity. Regular mail orders are shipped promptly upon our return. We currently have on hand a newly arrived batch of prop hubs ($299), we always have hybrid studs ($66), and an updated Manual for previous Manual owners is $30 through Sept. 1. These prices are good within the U.S. There are shipping charges that apply outside this country. E-mail if you'd like to order a prop hub through PayPal - the other items are available through the Online Catalog.

Subj: Parts
Date: 7/12/02

I'm currently looking for Corvair parts and wondering if I can get them from you and how much. I'm looking for a cam and gear, lifters, rod and main inserts all standard, set of rings standard, and a full gasket set, for a 1966 164cid. Can you help me?

Reply from WW:
Our current Conversion Manual contains sources for all these parts. Are you planning on building an aircraft motor? I saw your note about standard rings. I have a lot of experience which suggests using stock bore cast pistons is a tremendous mistake, especially on honed cylinders. I highly suggest overbored cylinders with forged pistons for any type of flight vehicle. .

Subj: Corvair on Europa
Date: 7/11/02

I was intrigued to see you mention this. "In the coming months and years, out of builders' workshops will come inexpensive, successful Corvair conversions powering other designs such as Zenair 601s, Europas ..." Do you have any details? Europa is strongly recommending Rotax, but I'm not excited about paying that much cash. It could make the difference for me between building one and not.

Reply from WW:
I know the Europa fairly well. My hangar mate and fellow Corvair owner Kevin built the two factory XS demonstrators which were on the cover of Sport Aviation two years ago. Although it's a tight fit, I believe the Corvair would work well. Les Van Meter in California is the primary builder pursuing the Europa/Corvair combination. The very odd shape of the Europa firewall makes it a challenging installation, but certainly do-able. Last I heard, the firewall forward package with the Rotax cost more than $25,000 from Europa. A Corvair installation could be accomplished for less than a third of this.

Subj: Dual Ignition
Date: 7/10/02

If you are using dual points, are you also using 2 caps and coils through some combiner?

Reply from WW:
The dual ignition system I perfected several years ago has two of everything that would be affected by heat, the primary killer of ignition systems. These items are points, coils, capacitors and resistors. Items like plugs, wires and caps withstand high heat. The two coils/one cap is resolved with an MSD coil splitter. The system is completely detailed in the new Conversion Manual.

Subj: 1964 110hp motor
Date: 7/9/02

I found a 1964 110hp motor, but I'm unclear as to whether you recommend it or not.

Reply from WW:
The '64 110hp will make a good conversion. We did several of these in the shop last year. The only difference between '64 and 1965-69 is a slight change in head gasket diameter. Early Manuals that I wrote in 1996 encourage people to use '65 to '69 motors. But '64s have since proven to work just as well. Remember also that '64 cylinders must stay with '64 heads, but this combination can go on any '64-'69 case.

Subj: Oil
Date: 7/8/02

What oil do you recommend for the Corvair? What about synthetics?

Reply from WW:
Like most other GM engines from the 1960s, the Corvair was designed to run on 10W-30 mineral oil. When breaking in a new motor, you should use straight 30 weight non-detergent oil. Within two hours on the break-in stand, I dump the first batch of oil. I continue to run non-synthetic oil until the motor is broken in. This can take anywhere from two to five hours. After this, you can use synthetic oil. I h

Subj: Intake hose
Date: 7/7/02

I've seen pictures of Corvair engines with intake manifolds that have rubber hose connecting two sections. Is this required for expansion and retraction, and what type of hose should I use?

Reply from WW:
A few people are making intake manifolds like this. A good example is Mark Langford's KR motor. The rubber joints are not for expansion, but are for assembly. His intake tubes between the joint and the cylinder head are made of aluminum and are welded directly to the head. Most builders are not going for this level of customization. Standard intake manifolds, like the ones I've built, are all one piece and have no rubber connections. There's enough give in the intake manifold that I've never had one crack. If you are going to use hose connections in your manifold, let me suggest going to a NAPA store and getting filler neck hose for a gas tank. It's designed to be continously saturated with fuel and has a lot of fiber reinforcement. Do not be tempted to use something like radiator hose, as it is not up to the job.

Subj: Weight
Date: 7/6/02

I recently read an article in Custom Planes magazine in which the editor said there was an "excessive weight penalty" associated with using the Corvair motor. Is there some model of Corvair motor that's too heavy to use? Most of the numbers I see on the Corvair indicate it weighs the same as an O-200.

Reply from WW:
I respectfully submit that the editorial staff of Custom Planes is out of the loop. What you've heard about the Corvair weighing the same as an O-200 is quite correct. While there are many good editors in aviation writing who actively seek out new developments and trends, staying current with what's in the field, there will always be a few who blindly parrot unsubstantiated information. By the way, all models of the Corvair motor, 1960-69, weigh within one or two pounds of each other when converted for aircraft use. The 190cid Corvair with VW cylinders, commonly referred to as the 3,100cc motor, actually weighs 8 pounds less due to material removal.

Subj: Quench area
Date: 7/5/02
William, I'm reading a lot about quench area but know nothing about it. Can you give me info on it? Thanks.
Reply from WW: In short, quench area is the flat area inside the combustion chamber which the piston will come close to at top dead center. Although it takes up space in the combustion chamber, and raises the compression ratio, it will actually allow you to run on lower octane fuel and have greater efficiency and detonation resistance. How it accomplishes these things is by generating turbulence in the combustion chamber. When the piston comes to TDC, the air and fuel on the quench side of the chamber gets squished over to the sparkplug side. When the gap here is less than 80 or 90/1000ths", the air/fuel mixture squirts to the other side of the chamber, keeping the mixture turbulent, active and homogenized. I have an extreme amount of practical in-flight experience, both positive and negative, with all types of Corvair cylinder heads. Although many people offer advice on this subject, I'm certain I'm the only person who's flown all the Corvair cylinder heads. Additionally, on this matter I consulted with a number of experts in person during my research. All of my findings are in the current Manual. There is a lot of talk on the Internet about this from people who have no experience running the motor with a propeller. On a stock rebuild of an overbored 164cid motor, you need not worry about this issue if you're using the correct cylinder heads.

Subj: Points
Date: 7/4/02

I'm using points ignition as per your Manual. I was thinking about trying to get a set of racing points for the Corvair to perhaps improve reliability. Do you know of anyone who sells these?

Reply from WW:
While I do recommend points ignition, I do not recommend heavy duty or racing points for the Corvair. The racing points have very high spring pressure to keep the rubbing block on the cam at extreme rpm. In a motor that will see 3,000-4,000rpm max, you don't need this kind of pressure. In fact, it tends to make the rubbing block wear much faster, and thus require more frequent adjustments. An important point is to ensure that the points you do use have a phenolic, not plastic, rubbing block. My current favorites are NAPA part no. CS788.

Subj: Thrust
Date: 7/3/02

I read Mark Langford's notes on Corvair College #3. It looks like everybody had a good time at your hangar. The question I have is this: the thrust numbers your tests showed seem kind of low compared to other numbers I've seen quoted for other engines, like Rotax 912s.

Reply from WW:
All of the propellers that we used were small diameter and high pitch. These props would be appropriate on aircraft like 180-200mph KRs and 160-180mp Dragonflys. Any 100hp motor with a prop like this will yield similar thrust numbers. If the propellers were appropriate for a low speed aircraft like a Pietenpol or Flybaby, they'd be larger in diameter with much less pitch and they would yield significantly higher amounts of static thrust.
Additionally, very few people accurately test thrust. The setup I've used for years is a hydraulic cylinder attached to a very accurate pressure gauge. It can quickly be calibrated before any test by suspending a known weight from it. I've never seen a setup using springs, scales or pulleys that I would call accurate.

Subj: New video?
Date: 7/2/02

I heard good reviews about the new video, but no details of what's exactly included. Can you fill me in on this? Thanks.

Reply from WW:
The new video is aimed at people who are unfamiliar with the Corvair and its installation. The video compares two different engines: a front start and a rear start installation. The rear start is Dave Vargesko's Vagabond Corvair engine in its running configuration on my test stand and the front start is Gary Coppen's Skycoupe installation. The video runs about an hour, covering the engine's size, shape, method of cooling and installation details. It stops short of internal assembly of the motor. You can order it through the Online Catalog or by sending check or money order for $25 for shipping in the U.S. or USD$40 for shipping to Canada or other international points to William Wynne, P.O. Box 290802, Port Orange, FL 32129-0802.

Subj: Thrust bearing
Date: 7/1/02

I notice that the thrust bearing is on the far end of the crank from the prop hub. Is there a problem with putting the thrust loads down the length of the crank in tension like this?

Reply from WW:
The question of thrust bearings frequently comes up among new converts. After 42 years of experience, the thrust bearing has proven remarkably reliable in its standard configuration. You're correct about the thrust loads in tension on the crank, but you must remember that these loads are very small compared to the other forces on the crank. Keep in mind that depressing the clutch pedal in the car puts a 2,200 pound compressive load on the crank. Chevrolet's stout construction and good oiling system have proven to work very well here.

Subj: CHT
Date: 6/30/02

What is a good cylinder head temp to operate the motor at? Does it have cooling problems without the blower fan? How do you measure CHT on the engine?

Reply from WW:
In the car, the Corvair motor had a 570F factory cylinder head temperature redline. While I'd never fly a motor this high, it's nice to know you've got a good cooling margin. I recommend cruising at a minimum CHT of 300F (350F would be better). In a sustained climb, I'd try and stay under 450F.
All this is easily achievable, even without the stock cooling fan. None of the engines I've built and flown since 1996 have had a cooling fan. The engines work well by applying standard aircraft cooling practice.
I measure CHT with a sparkplug gasket style probe. If I'm using just one, I put it on Cylinder #1. We have a lot more details on this in the new Conversion Manual under the headings Cooling and Instrumentation.

Subj: Ivo Props
Date: 6/29/02

A couple of people have been discussing on the Web using the Ivo in-flight adjustable prop. What's your feeling on this?

Reply from WW:
Under no circumstances should anyone use an Ivo prop on a Corvair motor. The particular design of the prop mounting bolts does not work reliably with direct drive four-stroke motors. I used to be an Ivo dealer, but I no longer am and do not recommend their products. The Ivo in-flight adjustable prop is too heavy for the Corvair's crank, and the basic airfoil shape and pitch in the root area makes for a prop with very low thrust. The high rpm capability of the Corvair (1,000rpm in excess of the Continental) greatly mitigates any need for in-flight adjustment, even on planes with 200mph top ends. I elaborate on this in the new Conversion Manual.

Subj: Loaner prop
Date: 6/28/02

I'm planning on starting my engine and giving it a good test run. I'm not sure which propeller I'll need. Is there a loaner prop available to borrow?

Reply from WW:
Yes, we have a loaner prop which is continuously in the field. If you'd like to borrow this prop, it is a Sterba (52x70) and makes a good engine break-in prop. I merely ask that people do not actually fly it. E-mail me privately and I'll give you details on how to borrow it.

Subj: Piston availability
Date: 6/27/02

I called around looking for .030 over TRW pistons, and it seems they're on back order for another few weeks. Is it OK to use other sizes?

Reply from WW:
I just spoke to Mark at Clark's and he confirmed that 30 over TRW pistons are in short supply nationwide until mid-August. There is no harm, however, in using .020 over, .040 over or .060 over. These sizes are all currently available. There's no downside to using any of these sizes.

Subj: Corvair Safety; your recent SAFETY BULLETIN

Date: 6/26/02 4:23:56 AM

From: dmperry@fix.net

I am struggling with the decision of which engine to choose for my plane. I am building a Q-200 and I really don't want to spend the money on the O-200 or similar engine. On the other hand, the Q-2/Q-200 lands fast and is a handful "off airport," so I want a high level of reliability.

In May I proposed (on the discussion group) an ignition that was totally redundant except at the sparkplug. You and others rightly pointed out that this was both complex and unproven and not a good system to install in a new airframe, and after thinking about it I decided you were right. I decided to go with the Corvair and use your partially duplicated ignition (dual points, condenser, coil) with the MSD 8210 and a single coil wire, distributor, rotor and cap.

However, after reading your "Safety Bulletin" (below) later in May I am back to worrying about this choice. I still see the coil wire, distributor, rotor and cap as single points of failure. Internal fracture or an external blow -- either one "could ruin your whole day."

For me, the hardest part of this whole process is the lack of numbers. It seems obvious to me that magnetos have to be redundant in aviation, because magnetos have a typical useful life of 400-1000 hours, but I have no idea how likely an ignition failure is with your modified, partially duplicated Corvair ignition.

Any comments or ideas?

At 07:24 PM 5/19/02 -0400, WilliamTCA@aol.com wrote

SUBJECT: Belt driven accessories on firewall end of motor.

CONCERN: If the belt frays or is thrown, measures should be taken to ensure that it will not dislodge the primary ignition wire from the coil or distributor cap. Additionally, fluid lines, such as fuel or oil pressure, should be protected from this possible occurrence.

DISTRIBUTION: I ask that all people converting Corvair motors be aware of this installation concern and be alert for it when observing conversions done by friends. This is a serious matter and a valid concern and I would hope that as friends and fellow aviators keep an eye out for this on installations.

BACKGROUND: I recently had a chance to speak with an experienced aviator who investigated an accident of a Ford V-6 powered Mustang II. This accident took the life of a friend of mine named John Blackburn. The man I spoke to was on the scene the day of the accident and later acquired the wreckage. The cause of the accident in his opinion was a frayed V-belt which knocked the high voltage wire from the MSD unit on the firewall to the center of the distributor cap. Although this is a different motor, the close proximity of the Corvair distributor and the proliferation of V-belts on the firewall end of the motor make this a valid concern.

William Wynne

May 19, 2002

I feel the ignition system we developed is the most reliable and flight proven one. I have read and understood your concerns about the single failure points. You are correct. I can only say that I feel it is reliable enough for flight as we have it now. With proper care, it gives a lot of warning when it needs attention, which is very desirable. There are a lot of reasons why aircraft have 2 magnetos, and a lot of it's due to having 5" bore diameters and low compression ratios. Also note there are a number of certified engines that use a Bendix D2000 mag which is driven by a single gear and this meets FAA approval and the pilots who flew these engines for years never knew the difference.

I hope you understand my tone and concern on the discussion group. I just want everybody to understand the risks associated with new developments. It certainly sounds like you thought this through and understand them a lot more than most. We get a lot of guys who make cavalier recommendations, encourage other people to use them, but always seem to bow out at flying them themselves. I'm not suggesting your inquiry was one of these, but you understand the type of thing I'm trying to restrain.

Subj: Parts Clarification Needed

Date: 6/24/02

From: pjohnson@voyageur.ca

The TRW and Sealed Power part numbers you have in your Manual (I'm owner of Manual 5099), are the piston and ring set numbers for .030 overbore? I would assume they are but I feel compelled to confirm.

Thanks William!

Usually you add a -30 suffix. Keep in mind that distributors like Clark's have their own part number for these same pieces. 30s can be frequently sold out at this time of year. There's nothing wrong with the other sizes like 20, 40 and 60.

Subj: firewall forward weight

Date: 6/24/02

From: farmerdel@rocketmail.com

Pulled the 'vair engine for the last time and got a final firewall forward weight* of 220 lbs., so about 10-13 lbs. more than the 3,300. I will still be working on a few things to cut it down a little more. But I'll take that. I'm also working on myself to get from 195 lbs. down to 185 (3 down 7 to go), so I should be in good shape.

*includes, starter,alternator,prop,carb,intake and exhaust, ignition coils, etc

Thanks for the weight update. I found it very interesting.
Many people ask about all up weights, and this installation will give them a much better idea. To people just reading this, also note that this is a standard displacement motor and could be made about 7-8 lbs. lighter if it were a 3,100 motor. Del has taken a few measures to cut a little more weight out than most guys typically do. He's a very clever guy who is one of the very few people putting a Corvair in a Sonex. I do not regularly endorse this idea because you have to be a very mechanically clever guy like Del to pull off the installation successfully. Please see Maximum Horsepower for further details of the Corvair/Sonex combination.

Subj: Engines of course

Date: 6/20/02

From: GPHILFLIER@aol.com

My dad and I have plans for a Pietenpol and are starting soon. I want your engine. I have built several engines so turning tools is not a fear factor. Could you tell me which engine I would need? hp etc. I am planing to purchase your Manual but I am so excited that I need some innput. Do you sell engines? I have found a complete car for $450.00 but it is a '63. Is that year good?

Hope to hear from you or your staff soon.

Congratulations on your new project. The motor you want is a 1964-69 95hp or 110hp. The '63 is no good. The Manual contains complete information, part nos., etc., on core motors. $100 to $200 is a fair price for an engine to start with, as long as it's complete. Most people are spending between $1,800 and $2,500 to finish their own motor. We do occasionally sell motors, but with labor they cost more than this. I encourage everyone to build their own motor. I know of no one who built their own motor and found it more difficult than they expected. Of course, if you run into a tough spot, we'll be there to help.

Subj: At Oshkosh?

Date: 6/14/02

From: hubbuch@rohmhaas.com

I am doing some basic investigation and considering the conversion of a Corvair engine for a Sonerai 2 Stretch.

1) Will this be a good match?

2) Will you be at Oshkosh 2002, and will you present a seminar?

Great web site & info.

The only person I know flying a Corvair in a Sonerai IIS is Gene Forsthofel in Duluth, Minn. He has a unique installation, with a starter and distributor mounted behind the engine. This makes his airplane a single seater. It would take significant work to get an installation that would preserve both seats. Gene tells me he flew the airplane 25 to 30 hours last year. He said it flies very well.

Yes, I will be giving forums at Oshkosh and the Pietenpol fly-in at Brodhead this year. Check FlyCorvair.com News! for details. And thanks for the kind words.

Subj: video and manual

Date: 6/14/02 7:13:11 PM

From: taildrags@hotmail.com

Thanks for your continuing contributions to engine conversion and to sport aviation. I'm still waiting for some parts from Corvair Underground to continue my rebuild, but in the meantime would like to order the video and manual update from you. You indicated a price for the video of $25 and Manual update of $30 until July 4. I will send you a check for $55 but would like to know if you need anything else, such as the registration page from my existing manual or etc.

Let me know; thanks!

Yes, your prices are correct for the update and video. All you need to send us is your old Manual cover page with the serial number so we can retire it. We're extending the reduced price on the new Manual to all people who had serial numbers 5,000 and lower. People who had not previously purchased a Manual can purchase the new 127-page Manual for $59. Please don't forget to return the registration form and liability statement from the new Manual. These are on the last two pages. Thanks.

Subj: avid flyer

Date: 6/13/02 5:20:10 AM

From: Mhflys1@aol.com

I am considering a long term project using a Corvair engine in an Avid Flyer. There are numerous people using heavy Subarus, so I know the Corvair would be lighter. I'm sure I could follow your Manual and do the rebuilding myself and get any necessary machining done. But where would I get help on fabricating an engine mount. I don't weld and would want something like that done by someone who knew what they were doing. Any thoughts?

Denny in Seattle,
You're quite correct that a direct drive Corvair is lighter than a Subaru EA-81 with a reduction. Keep in mind that the very early models of Avids were not strong enough for 220 lb. engines. The later ones are built much heavier.

The new Manual has many pages of information and drawings on motor mount construction. We also now offer pre-made trays and spools to give you a running start at a mount. Armed with these two things, it should not be difficult to get the help of an experienced guy in your EAA chapter. The Corvair mount is not a difficult one to build, and I would be happy to advise you with any detailed question you have. Don't let a hurdle like the mount stop you from having the engine you want in the plane of your choice.

Subj: manual

Date: 6/11/02 6:40:13 AM

From: rloer@mighty.net

I am building , from plans, a Light Miniature Aircraft full size Cub. If I keep the engine weight under 225 lbs or so is the direct drive Corvair suitable for me? Youe best observations are all I expect.

I'm pretty sure it's a good combination. I've seen these plans, and it should produce a pretty light aircraft. Remember, Cubs originally flew at about 720 lbs. with a 65 Continental. The LMA plane should be lighter than this, even with an electric start Corvair. The additional power should make it a strong performer.

Subj: cooling for corvair

Date: 6/9/02 2:01:06 AM

From: phaedra@scsinternet.com

Hi William,

Just did our first test flight today on out Piet using a direct drive Corvair. We are using straight ram air to cool it, but found that the left side cylinders are running very hot--600+ degrees. The right side was just fine at about 350 degrees. We are using a 3 bladed Warp drive prop set at 12 degrees. We are going to try installing a different cooling vent on the left side a la Stinson, but I would welcome any suggestions.

Thanks again by the way for your help in suggesting a pre-1989 Suburu starter motor. It works slick!

Thanks in advance

First off, congratulations on flying. Your hard work and perseverance has paid off with an initial flight. About the cooling, the first thing I'd suspect is a bad sending unit on the left hand side. Try reversing them and see if you get the same reading on a ground run. If it's actually running this hot, you know it's something only to do with that bank. This eliminates shared items like ignition and carburetion if you have a one-barrel carb on a tubular manifold. If it's a baffling issue, make sure that there's nothing blocking the air flow below the head. We once got into trouble because our carb heat box was only 1" below the cylinder head. I've found that two 3.5" x 9" inlets are more than enough to cool the motor in a Piet. Keep me posted as to your progress. If you still have trouble, e-mail pictures of the installation. I'll be able to give you more feedback.

Subj: What about a Great Lakes????

Date: 6/7/02 7:58:44 PM

From: brucerobinson@yahoo.com


I know a Great Lakes is heavy, but it was originally designed for a 90 horsepower engine. Large wing area, low loading. Have you heard of a Corvair in a Great Lakes? What do you think?

I actually know the Great Lakes fairly well. I'm president of EAA Chapter 288, Daytona Beach. In our Chapter, there are eight or nine guys who own Great Lakes. The smallest engine is a 150hp Lycoming and the largest is a 220hp Franklin. Most are 180hp Lycomings with constant speed props. The original engine you mentioned was a four-cylinder inline which made its rated power at very low rpm.

I do not believe the Corvair in any configuration would provide adequate performance for a Great Lakes. Being 3/4 the size of a Stearman, they are simply too big. On the other hand, there are several people working on installing Corvairs in Baby Great Lakes. Wayne Grimes, Newfoundland, has done a lot of nice work with this and has a modified airframe to make the aircraft appear to be more of a Dehaviland product. You can reach Wayne at wayne@metalworld.nf.ca.

Subj: Re: Video
Date: 6/6/02 6:59:35 PM
From: kr2cooper@msn.com
Received and viewed your video. Very informative and very well done. I'm confused on one point. I spent over 20 years in Army aviation and I thought a fine tuning tool was a BFH (big %$#@ hammer).

All my training's been in general aviation where the 18" crescent wrench is the tool of last resort.

Note To Our Readers: Jack's referring to our new introductory video, available through the Online Catalog. At the end of the one-hour video, our editor, Merrill Issacson, included several humorous outtakes, one of which involves an 18" crescent wrench.

Subj: Manual -- Problem (pages missing)

Date: 6/5/02 2:57:21 AM

From: dmperry@fix.net

Dear William:
This problem just cropped up. I am missing pages 36 and 37 of your Corvair Conversion Manual, which is the back of one page and the front of the next. At least one other builder has the same problem. I thought I should E-mail you direct.


PS: To anyone who doesn't have it yet, WW's new manual is AWESOME!!! (yeah, that's my kids talkin') The new manual has much more detailed discussions of what doesn't work and why. Worth every penny!

Thank you for the great review and the heads up. I apologize for the inconvenience. Check the Conversion Manual section for pages 36 and 37, and also page 59, which was missing from the initial Manual run.

Subj: Re: Corvair Engines

Date: 6/4/02 1:03:32 PM

From: vk3eka@yahoo.com

I am presently on the Island of St Helena in the South Atlantic Ocean. We do not have facilities to purchase money orders or bank cheques. Do you know anybody that accepts credit cards who could send me a copy of your new manual?

Sorry for the inconvenience.

No inconvenience at all. We now accept credit cards through PayPal. Check the Online Catalog for details.

How is the ghost of Napolean treating you?

Subj: clearance

Date: 6/3/02 12:50:19 AM

From: antdea@iprimus.com.au

Hello William,
I would like like to know what piston to barrel clearance is required when boring the barrels. I don't have a workshop manual yet but would like to get this part done and out of the way.

Yes, the piston is different. The cylinder clearance is 3-4/1000ths for forged pistons.

Subj: Corvair for Pober Jr ACE

Date: 6/1/02 10:35:51 PM

From: wdjbm@bbtel.com

OK, I'm interested what would work best for the Pober Jr. ACE.
Any provisions for in flight mixture control?
How do you retard the timing to get it started?
Do you know of anybody in the Kentucky area who is using a Corvair aircraft engine?
Thanks again, look forward to your reply

Thanks for your questions. Please take a look at the pictures of Ed Perry's Junior Ace on the News! page of flycorvair.com. Pictures of Jake Jaks' Junior Ace, under construction, are posted elsewhere on the Web site.

Each of these gentlemen is using a standard 164cid 100hp engine built to my specifications, as outlined in the Conversion Manual. Jake's engine was actually built in my hangar during the first Corvair College.

A number of the carburetors which I recommend have in-flight mixture control. The most popular of these would be the Monnett Aero-Carb and the MA3 from Marvel Schebler. The Stromberg NA3, also a popular carb, has a moderately effective mixture control. The Manual, available at the Online Cataolg, has the complete story on each of these.

As for timing control, this is completely handled by the mechanical advance of the Corvair's distributor. There are many photos of my distributor recurving machine on the site. Although it's not required, I recurve distributors for a modest fee. When set correctly, the engine will be easy to start, idle smoothly and advance to a full power setting.

We have complete records on thousands of Manual owners. Almost all of these guys have opted to share their names with other builders. This is a service we're happy to offer to Manual owners.

Subj: Corvair College 2002

Date: 5/30/02 7:06:09 PM

From: PaulZimm@attbi.com

I enjoyed attending the 2002 Corvair College. I carried in several boxes of parts, and a lot of desire, and now I have a completed Engine (less ignition, carb, alt, and starter) ready to get installed in my DragonFly! I am in the process of unloading it from my truck and I wanted to say thanks for all of the help! It was one of the most enjoyable events I have ever attended. Only problem is, WE all worked tooooooo hard! Thanks to you, and especially GRACE!

Thanks again, and it was a pleasure to meet you, Grace, Kevin, Brigid, and Gus!


Thanks Paul. It was great to meet you, along with others we'd only conversed with via e-mail, in person. A sincere desire to put the motor together carefully is the key ingredient common to all our successful customers. Helping builders meet each other in person, where everyone gets to help out, is the best part of Corvair College.

November-December 2003 Q & A Page

October 2003 Q & A Page

September 2003 Q & A Page

August 2003 Q & A Page

July 2003 Q & A Page

January-June 2003 Q & A Page

January-November 2003 Q & A Page

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