William Wynne

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

Ask The Authority!

September 2003 Daily Question & Answers

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November-December 2003 Q & A Page

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January-June 2003 Q & A Page

2002 Q & A Page

then by all means e-mail William at WilliamTCA@aol.com. Thank you.

Subj: Corvair/Titan
Date: 9/30/03

I'm planning to build a Titan IIS (pusher). Would one of your Corvair engines with electric start be appropriate for this configuration?

Rich Latta, Linwood, N.J., rlatta7259@aol.com
Reply from WW:
I have developed many engine installations and components for the Corvair motor. Almost all of this has been done for traditional, plans built, tractor aircraft. I know what a Titan Tornado is, but have never looked at it for the purpose of installing a Corvair motor. Being a kit and an outgrowth of ultralight technology, the airframe may be too lightly built for a Corvair, or may not have drawings available for me to use to work up an engine installation. Without questions like this answered, I'm not able to offer you much assistance beyond the engine itself.

Subj: Corvair in Mini-Imp
Date: 9/29/03

Dude.....Help..... I've got this engine that has the the following codes: Heads: 3856759; Case: 3819616; Engine: TI005RD. But I can't find 8409 anywhere on the crank?........ Now I'm wondering if the cylinders or the case are any good for converting....... What's up?......Do I have a mixed matched engine here or what ???? Thanks...I. A.........

Robert Parker, rpa2976@earthlink.net
Reply from WW:
Your engine is a 1965 110hp and it's perfect for the conversion. It is not a mix and match engine. All of the numbers you've given me here indicate that the engine is a matched unit. The head number and case letter code are in your Conversion Manual as good numbers. There's also a picture in the Manual showing the location of the 8409 numbers on the crankshaft. You're in good shape. Keep going.

Subj: Manual Update
Date: 9/28/03

I bought the Manual from you a couple of years ago (1999 version) and I see that there is now a new update. My Manual # is 2036. I was wondering if I could send you this one back and pay the difference to get the new updated Manual.

Also, what are your thoughts on buying a case, heads, cam and crank from a catalog and scratch building an engine from parts? It seems like this is about all you use from the origianl engine, so what is the advantage of buying an old engine, ripping it all apart, and throwing 50 percent of it away? I realize there are lots of bolts and gaskets and stuff, but the catalogs sell kits of these things too.

Jason Baker, jasonjamesbaker@comcast.net
Reply from WW:
There are quite a number of parts that we use from a core motor, far more than you're thinking of at this point. You'd spend a whole lot of money to buy them individually. You're much better off buying a core motor. We have hundreds of people building Corvairs, and we've had to find a core motor for only a handful of them outside Australia and England. Most people find them in their hometowns.

The new Conversion Manual is greatly expanded over the edition you have. It's now 100+ pages. If you mail in a copy of the cover of your old Conversion Manual, along with a completed Liability Statement, available at The Corvair Authority Liability Statement Page, the cost is $30 for delivery in the U.S. payable by check or money order to William Wynne, P.O. Box 290802, Port Orange, FL 32129-0802.

Subj: Corvair for STOL
Date: 9/27/03

I am a private pilot that had to sell of my share of a P140 to put money down on our house when my wife and I got married. Now, it is not all that bad because a condition of marriage (Like right before the service!) was to start work on my dream within 5-6 years. Well I am at year 4.5 and my wife is very supportive. Mostly because her and the kids have been subliminally subjected to countless hours of aviation video, TV, toys and in sundry forms of propaganda.

At any rate, I just want to say that I try and keep as much informed about the culture as possible. I wish to express strong congratulations on your contribution in this culture beyond just the business side of aviation but obviously expanding on the very essence of the sport and culture of aviation.

I look forward to pursuing a Corvair powered 2-place STOL build solution in the upcoming future. And now a request of opinion. Zenair 701/Corvair combination? I have seen a few 601s, but that is a totally different craft. Any other rough field 2-place STOL A/C that in your opinion that could end up on a pair of amphibs eventually? I know many say match power to the A/C, but I am just so impressed with the Corvair community

Regards and great work for your community.

Derek Hulbig, Ontario, Canada, hulbigd@rogers.com
Reply from WW:
The Zenith people try to discourage builders from installing engines which weigh more than 200 pounds firewall forward on their 701 design. However, there are a number of other designs which could be successfully operated on amphibious floats and successfully operated at 100hp. These include airplanes like the Pegzair and some J-3 replicas.

Hats off to your wife for understanding that men who are passionate about airplanes make better husbands.

And thank you for your kind words.

Subj: Less horsepower
Date: 9/26/03

I have a '63 Corvair engine with new pistons, rods, OT-10 cam and cylinders.

I was thinking of using this engine, even though it has less horsepower than the newer engines, because I will have to fly on the new Sport Pilot License.

I want to build a KR2S and slow it down with a climb prop and a lower H/P engine. I will also have to find a way to slow down the landing.

Aside from the low H/P, is there any reason not to build this engine? I haven't started yet and maybe I can trade the Corvair Club here for newer case and heads but I don't really need all that power. Thanks for any help you can give.

Patrick Driscoll, patrick36@usfamily.net
Reply from WW:
There are a number of reasons that make the 1964-69 engines more desirable. Forged pistons, for example, are readily available for the '64-69 motors, but much harder to find for the 1960-63s. I highly recommend you go back and search out a late model engine. A simple set of flaps might very well get a KR2 with the S wing into the Sport Pilot category. Good luck with your building. It's certainly a worthwhile endeavor.

Subj: Heads, cranks, distributors
Date: 9/25/03

After sitting my butt down long enough to read more of your Conversion Manual, I did manage to find the page that lists the number for the correct heads and they are the 9:1 heads. Head number on both are: 3856632.

Do you also replace or could you replace the main gear on the shaft on every hub you do? Do you, upon request, replace the distributor gear? Mine looks a little worn. I plan on packaging up my crank and sending it down your way here in a week or two. Also, I would need to get the .010 oversize main bearings, correct? Thanks in advance.

John Esch, Independence, Ore., jfesch@earthlink.net
Reply from WW:
Your heads are 1964 110s. They are perfect for the conversion. Keep in mind that you will need to use 1964 cylinders with these. On your crank, I can replace the gear for $100, labor included. I have many spare distributor drive gears, and if there's something wrong with yours, I'll change it at no charge. Yes, you will need .010 under bearings.

Subj: Corvair for T-40
Date: 9/24/03

I'm considering building one of the Turner T-40 planes, preferably one of the two place variety. A buddy from work has just picked up a Corvair engine for his Air Camper, and the simplicity, convenience, price tag, reliablity, etc., etc. has peaked my interest. The T-40s range in hp from 85 to 150. Would the Corvair be a candidate for a T-40, and if so, which one(s)? Do you know of anyone who is building such a plane? Thanks for any help you can provide.

Jason Porter, jporter147@comcast.net
Reply from WW:
We get a question on T-40s once or twice a year. I strongly suspect the reason why the T-40 design stays around is because they were featured in some of Tony Bingelis' How-To books. In all the airshows I've ever attended, I'm not sure I've ever seen one in person. There are downsides to building a design which may not be currently supported. I'd investigate this fully before deciding to build any design. As to the Corvair's applicability, if the plane flew on an 85, it will certainly fly on a Corvair motor. Keep in mind that the 85hp version may not be the two-seater you mention.

Subj: Prop Hub
Date: 9/23/03

You may have received my phone message this a.m. re: my checking out a local shop to make the prop hub. I expect you chuckled all the way to wherever you were headed as you are probably aware that your price for the hub is a "steal," "real deal," "bargain," you name it. I sort of thought that was what I would discover. I shall be ordering one in the near future.

If you have some spare time, I would enjoy discussing the Christavia Mk-II/Corvair project in Canada where builder thought it necessary to use Volkswagen reduction gear to attain good cruise and climb. Seems he thinks it can't be accomplished straight out of the box with direct drive. I am starting a similar project but heed your words re: direct drive, keep it simple, etc.

Enjoyed your first forum at OSH.

Roy Rogers, Manual #5594, carolandroy@tds.net
Reply from WW:
I've worked very hard to keep prices down over the years. Glad to hear from another guy who appreciates it.

My experience with direct drive Corvairs suggest a good, simple flying plane can be had with a direct drive motor. The Christavia is a fairly efficient airframe, and I'm sure a direct drive Corvair would have no problem pulling it.

Subj: Ultravair
Date: 9/21/03

At Oshkosh this year, an ultralight had a 1/3 Corvair engine on it and I really want one. Now I fly a Kitfox Lite with the 2SI 2-stroke engine.

I really hate the idea of cutting a good block for the 1/3 engine (similar to cutting a VW in half) and am looking for a block and crank (164 cid) that has damage anywhere except the rear (flywheel) 1/3. You can take a look at the engine at http://www.ultravair.com/index.html. I have called salvages around here and no one has any Corvairs. If you know any such engines, please let me know. Thanks, Stan

Stan, stan33o@yahoo.com
Reply from WW:
Fletcher Burns, Mr. ultravair.com, is a friend of ours and I think he's on to something good here. As for your engine search, we've tossed away a lot of motors that would have been useful for his conversion, but don't have any currently. Put out the word in your hometown that you're looking for one and it shouldn't be too hard to find. Hundreds of our customers have found engines without much trouble.

Subj: Corvair Specs
Date: 9/20/03

I was wondering what the max. cylinder size could be for standard pistons. I have the tools to hone the cylinders, but not to bore them. I am trying to find out what the max. reading could be so I can use standard pistons. I cut the ridge out and there was none to speak of. I know that Clark's says they will hone cylinders and if they take off less than .006 you can use standard pistons. But I don't know what a standard cylinder measures. Thank you for your help.

Jim Sury, jimsury@fbtc.net
Reply from WW:
The stock bore is 3.437. We have built motors with standard size TRW forged pistons, and I think it's best to keep the wall clearance to about 5/1000" or less; 3 would be minimum.

Subj: Corvair Engine Search, Jr. Ace
Date: 9/19/03

I e-mailed you earlier about a Corben Jr. Ace with one of your engines. You e-mailed back that the plane was damaged and no longer flying. Thank you for getting back to me on that.

At any rate, I'm on the search for a Corvair to convert for my Corben Jr. Ace. I've found three near me in Missouri. Here are the numbers: TO8267 (supposedly 110 HP, had a manual transmission); TOI27RD (supposedly 90 HP, had automatic transmission); TO325ZF (don't know diddly about this one).

Please help with these two key questions: 1) Can you confirm which are 110 HP and suitable for the Wynne conversion? 2) If I choose to go with the manual transmission engine (TO8267), how tough is it to find an automatic bell housing for the conversion?

I plan to purchase your Manual and various other parts from you. However, I first want to make sure I can find a decent engine to convert. My Corben Jr. Ace will hopefully be another successful Corvair bird. It's a good airplane, just very underpowered. It's actually a Baby Ace Model E which has a 26.5 foot wing span. Solo performance isn't bad, but performance is bad with another average sized human sitting next to me. Thanks for the help. It's greatly appreciated.

Greg Bacon, Prairie Home, MO, gbacon67@direcway.com
Reply from WW:
Of the engines listed, the one with the RD suffix is a 110 1965-69. It is your best bet. When people tell you things like "90hp Corvair motor," they're guessing - there was no such thing as a 90hp Corvair motor. The RD was a manual transmission motor, but this does not matter. You can cut either bell housing down to make a front cover.

As you know, the short wing span is part of your airplane's climb performance issues. I think a lot of people casually acquainted with the airplanes don't notice the Pober airplanes' longer wingspans. In the 26 foot range, you'd be surprised how much a foot or 18" on either side would improve the climb performance.

Subj: Scale Drawings
Date: 9/18/03

Last year I wrote to you concerning the GN-1 Aircamper steel tube frame. You advised me to get a copy of the old Flying and Glider Manual and go with the Piet steel tube frame. I finally got on the ball and ordered one and I'm thrilled! Thanks for setting me on the right course!

Are any scale drawings of the Corvair engine available so I could work on some cowl designs? (Not that I'm jumping ahead or anything!) Thanks again and take care! Sincerely,

Greg Murphy, Pietenpol, Elwood, Ind., windsock@onemain.com
Reply from WW:
One of the back issues of the Corvair Flyer newsletter (available as a collection for $10 for U.S. delivery payable by check or money order to William Wynne, P.O. Box 290802, Port Orange, FL 32129-0802) has good 3-view drawings which can be reduced or enlarged on a copier. These were done by our friend Dan Benson. They reproduce very well.

Glad to hear you're on the right building track. When looking at photos of my Pietenpol, realize I raised the thrust level of the engine up to the top longeron. Flew slightly better, easier to cowl, and looked better.

Subj: Oil System Tests
Date: 9/10-16/03


Below are five pictures from oil system tests. I intend to expand on this subject in the next Corvair Flyer.
Above is a 12-plate cooler, with proper lines, sitting in an ice bath. Cold soaking it like this replicates a start at 30 or 40F. Oil pressure is measured on the incoming and outgoing lines.
Above is the stock filter, also in an ice bath.
This three-gauge panel shows:
  • 1. Regulated oil pressure before the filter.
  • 2. After the filter, before the cooler.
  • 3. After the cooler - this is the same pressure the oil gallery sees.

    This run shows clearly that a chilled filter has very little pressure drop, but the cooler is operating on the bypass. I later blocked the cooler lines to verify that the bypass was exactly 10psi.

  • The cooler was soaked in very hot water until it stabilized near 150F. This is a laser infrared thermometer reading.
    With the cooler temperature elevated, it still has a substantial pressure drop. Between the ice and hot water, I also ran an 80F ambient temp test. I was surprised to see that the cooler still used the bypass.
    The oil in the engine was 10W40 mineral oil. The oil system functions just as GM intended. It bypasses the cooler until the temperature comes up. This allows the oil to properly lubricate the engine at any temperature you'd like to go flying at.

    Subj: Corvair Powered Zenair 601XL
    Date: 9/9/03


    Corvair/Colt builder Dave Vargesko and I just returned from a 2,500 mile round trip to the Zenair factory in one weekend. We picked up a complete Zenair 601XL taildragger kit. After speaking with the Heinz family extensively, Grace and I decided that this should be our 2004 demonstrator aircraft. In the next few days, we'll start a new page on www.FlyCorvair.com so other 601 builders can track our progress on this.

    Subj: Piston Pin Pressing Jig
    Date: 9/8/03


    Several questions surfaced recently about the little jig I use to press piston pins. My Engine Assembly Video Part II will be finished this week. It shows the jig in action. I thought I'd share this photo of it to help give people an idea of the shape. I will include a drawing of the jig in the next Corvair Flyer newsletter. Subscriptions are still $20 a year in the U.S., $25 for international builders, payable by check or money order in U.S. Dollars to William Wynne, P.O. Box 290802, Port Orange, FL 32129-0802, or by credit card at the Online Catalog of Parts available from The Corvair Authority.

    Subj: Good Head Castings
    Date: 9/7/03


    Here are two photos of the major castings we use for flight heads: the 110 and the 95hp. Please note that there are also engines like smog 110s that have different castings. Use these two photos to identify good heads. You can use two heads with different numbers as long as they have the same chamber shape.

    Above is a standard 110 head. It has a distinctive combustion chamber shape. Please note that early cylinder heads, 1960-63, can also bear a resemblence to the 1964-69 110s. Looking at the chamber shape and checking the numbers against those in the Conversion Manual will identify usable heads.

    A 95hp head is pictured above. It has a straight line defining the top of the flat quench area. Some of these heads are listed as 8:1 compression. In reality, they're slightly higher. The shape shown here, along with the correct casting number for a 1964-69 engine, identifies a good flight head. In my experience, there is very little difference in output of identical engines differing only in 95 or 110hp heads. The factory horsepower differences in these two motors were based on the cam, timing and carburetor jetting. Since we're changing all of these things, and the heads have identical size valves, I have found the slight difference in compression ratio between the two motors to produce a negligible difference in final output. Either motor will produce 100hp when converted according to my Conversion Manual.

    Subj: Bad Head
    Date: 9/6/03

    The photo above is an example of the combustion chamber style that should not be flown. It is known by several slang terms, including open chamber, turbo and smog. The example in the photo is a 3880708 head that we flew in my original tests. The Manual has the whole story on that. In short, this chamber style has no flat quench area, and should not be used in a flight motor. Some of these heads, like the 3878564, came on factory turbocharged Corvairs and are very valuable to Corvair car restorers and collectors. If you have a set of heads like this, there are many car guys who would gladly trade you for a set of the good heads in excellent condition.

    Subj: Completed Engine Storage Time
    Date: 9/5/03

    I am one of those guys who bought the wrong engine before reading your Manual. With your encouragement I was able to locate a set of 110 heads and believe that I am ready for dissassembly. In an earlier communication I believe you mentioned to an e-mailer that you knew of an engine that sat completed for 20 months before installation. I believe this may be my case. Any further thoughts? Thanks,

    Gary, gboothe@calply.com
    Reply from WW:
    The motor could go a lot longer than 20 months in a reasonably dry place. ACF-50 is the best spray I know of for preventing corrosion. If the rods and crank were sprayed with it after assembly, as well as the steel parts of the valve train, it would last many years.

    Subj: Introduction
    Date: 9/4/03

    My name is Jonathan and I am building a Vision. I am 23, currently residing in southern New Mexico, and I'm an enlisted active duty member of the Air Force. I've been serving for over 6 years and I'm a jet mechanic. I worked F-16s for my first four years and the past two years I've been working on the F-117. I've always had a love for flying and I earned my private certificate in January before we deployed for Iraqi Freedom. This is my first attempt at building an airplane and it has been educational while teaching me new skills.

    I flew down for a build session with Steve at the end of July and the Vison Personal Cruiser that Morgan is building is beautiful. The pictures of it with that nice blue engine hanging off of the front are beautiful. In person, it looks even better.

    I have a long ways to go before I finish (I'm completing my HStab right now) but deciding on a powerplant now will help facilitate getting it accomplished when the time comes. I've never put an engine together myself but I would like to do so on this project. My interest for the Corvair engine stems from what I call the ratio of 3: money to power to reliability. A Lycoming 0-320 would be my ideal choice but the total cost of the engine during its life (rebuilds, yearly maintenance) just put it out of my reach.

    The 120hp Corvair engine seems like a good choice but that's just looking at numbers on paper. If you were putting a Corvair engine in a two-seat, VFR, EX wing Vision, which one would you choose, 100hp or 120hp?

    If I make it back to Steve's, I'd love to see your hangar. Thank you for your time, honest Web site, and for furthering experimental aviation. Guys like you and Steve are making it easier and cheaper for guys like me to make my dreams come true. Take care and have a great weekend.

    Jonathan Dingus, Vision, New Mexico, jonathan@jonathandingus.com
    Reply from WW:
    We very much enjoyed your photo. I'd seen it before. When you first sent it out, Steve showed many, many people at our home airport. I come from a big military family, and let me say most Americans, myself included, appreciate you serving your country at its time of need. It's an honor you'll have for the rest of your life.

    The engine you may be most interested in is my work turbocharging the 100hp Corvair. In the end, it will have better altitude performance than a 3100cc 120hp. If it can maintain 100hp at 10,000 feet as I plan, it should exceed the performance of an O-320. My testing indicates that the total parts price in a turbo motor will be less than $4500. If you give me a few more months, I'll have the hard numbers and the system will be fully developed. The Vision is an exceptionally efficient airframe, and it has the space under the cowl required for such an installation. These unique attributes make it a very good match.

    Subj: 10-10, OT-10, Stripped plugs
    Date: 9/3/03

    I did manage to go to the Corvair Underground (CUG) and picked up the chassis manual, their 2004 parts manual, and cost manual. I verified the head numbers and the crank number and I do have a 1964 110 hp engine and 1962-63 102hp engine. Whew! Are the '64 heads the 9:1 heads you recommend?

    I may need to get new (used) heads due to taking out the spark plugs; at least 2 on each head were frozen and I think they are stripped due to the force to get them out and seeing no threads on the plugs. Ouch.

    The insides of the engine look pretty good, which still had badly needed oil change oil in it. I plan on sending my crank down to you to have the grind, safety shaft, and hub job done. Should I take the crank up to CUG and have them check out the crank first to make sure it is usable prior to sending it to you for mods? Can you explain the 10:10 grind? I plan on getting a new camshaft from them and many other parts.

    I will have lots of questions in the near future since my rear end will be relying on the front of my plane. Thanks again,

    John Esch, Independence, Ore., jfesch@earthlink.net
    Reply from WW:
    You can helicoil stripped sparkplug threads in Corvair heads. I've done it on a number of engines, and a great number of certified airplane engines have helicoils in the plug holes.
    Please note that the Corvair Underground does not have OT-10 cams. Clark's and Jeff Ballard, 805 644-0006, are the only two sources for the OT-10 cam. Last time I spoke to Jeff, he had a few on the shelf.
    10-10 means that the bearing journals have been reduced in diameter by 10/1000". This is done on a very special grinding machine that looks like a big lathe. The grinding wheels are up to 3 feet in diameter. Afterwards, you use bearings which are slightly thicker and thus the clearance is restored. This is a common rebuilding practice.
    Almost any Corvair 8409 crank from a running engine can be redone at our facility. Rarely do we get one that will not clean up with a .010 regrind.
    Send me the 7 digit number on the end of your head, but I'm almost sure it will be correct.

    Subj: Chief conversion
    Date: 9/2/03

    I am interested in building a Corvair engine to use in an Aeronca Chief project I have. Has this been done before and can you provide information regarding electronic ignition and fuel injection for this application? Thanks,

    Billy, ltlmtn@charter.net
    Reply from WW:
    I used to own a 1946 Chief. I think it's one of the best classic aircraft ever produced. Its fuselage structure and interior arrangement are exceptionally good.
    A Corvair motor would easily power an 11AC. There are FAA issues involved, unless you're doing a substantial amount of work to the airplane. Corvairs have been fuel injected, and have used electronic ignition, but I do not advocate flying either one of these systems. Neither one of them generally gives any type of warning before failing. Such a characteristic is unacceptable in machinery intended to fly. Conversely, carburetors and points ignition generally give lots of warning when they need attention, and rarely shut off in the blink of an eye.

    Subj: Hose Ends
    Date: 9/1/03


    A number of people have asked for a photograph of the hose ends we use.

    Clockwise from top right are:
  • 90 degree full flow swiveling -6
  • 180 degree full flow swiveling -6
  • Non-anodized -6 end, used for welded fittings, made by Earl's
  • Brass barbed fitting, never to be used in aircraft
  • -6 swivel fitting with 1/8" pipe outlet - good for pressure or temperature sending
  • Same thing made by different company
  • AN833-6D bulkhead elbow - a fitting like this is far more restrictive than a full flow 90
  • Thank you.

    November-December 2003 Q & A Page

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    July 2003 Q & A Page

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    2002 Q & A Page

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