William Wynne

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

Midwest Corvair Night Schools in Feb. 2005 -

Updated with Photos

Open E-Mail

February 2005

Welcome to the Open E-Mail Page at www.FlyCorvair.com. Here's the concept: We answer a lot of e-mail every day, and there are a number of really good questions that our R&D allows us to dispense valid advice from. Twice a week, Wednesdays and Sundays, we're going to post blocks of these questions with answers right here. Open e-mail allows us to dispense information and answer questions in a broad forum. By checking it out regularly, builders can expand their knowledge, and keep abreast of developments.

In many ways, it will function like an Internet discussion group, where builders can reference previous questions with follow ons or even write in to share their perspective of what worked for them. As an advantage over most Internet discussion groups, the discussion will stay friendly, focused on building and flying Corvair engines, and most important, because the discussion will be moderated and edited by us, all the technical information will be factual, useful and proven. There's still plenty of room to talk about different ideas and future plans, but the center of the discussion will be reality based information to help people who want to build and fly the Corvair achieve that goal.

Here's how it works: Simply click here, E-mail WilliamTCA@aol.com, and include the word Open in the subject line of your e-mail. Please include your name, state, provence or country, and type of aircraft you're building. If you own one of our Conversion Manuals, please include your Manual number. Our very busy travel schedule sometimes prevents us from answering e-mail as fast as it comes in. But we're making the commitment here to post blocks of answered Open E-mail questions twice a week. It is my intention in 2005 to focus 100% of my Internet communications through this Open E-mail format. Of course, regular business communications can be sent to us by normal e-mail with a different subject line. For the fastest response, please phone our hangar line, (386) 478-0396, which is forwarded to my cell phone when we're out of town (it's not necessary to call both). All of this is done to improve communications, maintain an informative, friendly conversation on Corvair conversions, and serve the ultimate goal of helping you safely build and fly your Corvair engine.

NOTE: To search for anything on this page, the toolbar on the top of your browser has an Edit function with a Find on This Page feature. Just type in the key word in which you're interested, and the Find feature will take you right to it.

Bonus Photo

Above is a photo of the 601 firewall forward display coming together. In the foreground is the air/oil separator, with a 5/8" aluminum vent line that leads out the bottom of the plane. The two other connections will go to the left hand valve cover. The gascolator and fuel pumps are installed on the far side. We're building this up to display it in the Zenith Aircraft booth at Sun 'N Fun. We're taking exact measurements and detailed photos of all the components installed on the firewall, in order to aid builders in creating their own professional looking installation. The dummy engine installed has our welded on intake pipe mod in view. We'll be taking the entire assembly to a CNC tube bending house that will produce our one piece intake manifolds and the primary tubes in our exhaust systems. These components will still be finish welded in our shop, but the CNC primary pipes will make the finished parts better looking and less expensive than handmade versions. This is a good example of our commitment to perfect the installation down to every last nut and bolt.

Subj: Remote Permacool Oil Filter adaptor part number
Date: 2/24/05

Can you give me the part number for the adapter you are using on your 601? The K&N filter HP-1004 I have does not seem to fit the Permacool #1791 (3/4"-16 thread which is a sloppy loose fit) or the #1793 (13/16"-16 thread which is too large for the filter). A source for the correct part would be a good thing also.

Thanks, Ron Whittington, Texas, Vari eze
Reply from WW:

The photos above and below show the oil filter installation on the 601 as it is today. People who have followed our R&D know that we'd previously tested two other oil filter locations. This was just basic R&D. The setup shown here is the final 601 installation which I encourage customers to emulate. We chose to install this on the 601 last week, so that our installation will be available for builders to inspect during the 2005 airshow season. Please note that the four fittings in these oil hoses are full flow hose ends. Ends of this style have almost no measurable drag on the oil flow. The top fittings are attached to one of our new Oil System top covers. They are 120 degree full flow AN-6 ends. The bottom fittings are full flow Earl's 90 degree swivel seal ends. Having a swivel seal end on one end of the hose allows a hose to lay down smoothly without stress. We will have these hoses available prefabricated for 601 installations shortly.

Permacool #1791 is the correct number for the part we use on all of our installations. It is readily available from SummitRacing.com. We flew about 40 hours with the HP-1004 filter. I agree with you, the fit was less than ideal. However, we currently fly and recommend the HP-1002 filter, top photo, which has an exact fit and all the same excellent features of K&N filters. These are readily availble at most auto parts stores.

Subj: Core Engine Acquired
Date: 2/24/05

Thanks for the new e-mail forum. I need your advice again. I recently purchased a "new" core engine and have decided to start it from scratch, though may proceed slowly. Engine is apart and clean. After reviewing my videos and Conversion Manual (I think essential for all builders), I see there was mention of replacing the crank flange if it had excessive pitting. Here in Michigan, with salt used in winter, I have pitting. The greatest area is less than 1/8 diameter and is just into the metal surface.
(1) Do I need to replace the gear/flange?
(2) At the risk of rehash, should I consider an offset woodruf key to be installed by Clark's when I get my OT-10 and new cam gear? (I remember discussion about advancing the timing with a wood ruf offset key - is it a good idea?)
(3) Is the Otto failsafe gear a good idea?
(4) And are regrind cams by Clark's still ok?
(5) Oil pumps: Is Clark's Proflow C3942 a good idea?

Again, thanks for all your support. Sorry I missed you on the Midwest Tour. My very short Florida vacation was over the week you were here in Michigan, and I couldn't trade the Florida warmth for anything. You guys proved how sacrificing 80 degrees for our Midwest weather is beyond dedication and into transcendence of mere mortality and comfort....or something...

Best, Jim Dankovich, 601XL, Michigan

Reply from WW:
Sounds like you have some serious pitting. This is usually a fairly oily area on an old Corvair engine, and we rarely see pitting on them. If you like, we can take care of replacing the gear in our shop if you send in your crank for the complete Drop in Crankshaft treatment.

Do not use an offset key, use a regular key. Clark's has both reground and new OT-10s. We have flown both and built engines using both. They both work well in flight engines. Same goes for the standard cam gear and the failsafe gear. The failsafe gear is only an absolute requirement on a reverse rotation engine.

I do not recommend high volume oil pumps on Corvair flight engines. They are not necessary, and they use more power and put more strain on the drive system. A pump like this in an airplane engine is trying to solve a problem that doesn't exist. Stick with the stock pump.

After our northern tour, I have nothing but the greatest respect for homebuilders who will toil in chilly weather to build the machine of their dreams. The only thing I could say in defense of the honor of Florida aircraft builders is that when the temperature hits 3 digits in the hangar, those of us with thin blood have no problem laying in a 12-hour day. But we truly know you northern builders are a lot tougher.

Subj: Reconditioned Rocker Arms
Date: 2/20/05

A while back you mentioned in an E-mail that you would soon be providing a reconditioning service for rocker arms. What is the status of this effort and what would be the projected cost (each, and/or per 12)? I've got 2 which have irregular valve stem contact areas.

Allen G. Wiesner, KR-2SS/TD S/N 1118, CorvAir S/N 6064, Ansonia, CT
Reply from WW:
We have not had time to finish off that product yet. Our projected cost is less than any other set of rockers, balls, nuts and studs on the market. We're still experimenting with a surface polisher with the correct radius to face the tips. If you get to the point where you need to do something, let us know & we'll send you 2 rockers to keep your project moving. We'll have more information on this after Sun 'N Fun.
Subj: Ohio Night School
Date: 2/19/05

I enjoyed your visit to Barber airport very much. It was informational and inspiring. The four-hour drive from Chillicothe to Alliance was well worth the trip. Thank you for sharing your knowledge and effort in helping.

Danny Cash, Manual #6360
P.S. Also enjoyed the Assembly Videos 1, 2 & 3. Very informative and thorough.
Reply from WW:
Builders who will drive hundreds of miles for a few hours of technical answers and some inspiration are really something. People who show this type of initiative are my bet for those who will start and finish and enjoy ambitious projects in aviation. I have found Corvair engine builders' common thread is the willingness to follow our proven path, even if it requires learning new skills and putting in some real effort. This is why I have such respect for our customers.
Subj: Tubing, Fuel Lines
Date: 2/18/05

I am still assembling materials for my 601HD with Corvair engine and would appreciate clarification of the following:

Your Manual indicates .065 1/2" tubing for tray and firewall spools, whereas your 601XL Mount used .058 tubing. Would the .058 tubing be suitable for my Corvair 601HD? Your manual suggests the use of gussets to reinforce the motor mount but your 601XL mount does not appear to use any gussets. Do you suggest gussets be used for additional strength on my 601HD? Do I require the seventh tube to counteract engine torque?

With respect to the fuel lines on your 601XL, did you use all solid 5052 3/8" aluminum from each wing tank to selector valve and from selector valve through firewall to gascolator or is fexible line required? Would 3/8" 3003 aluminum be acceptable to replace 5052?

Thanks, Bob Duns, Manual 5053, Zenith 601HD
Reply from WW:
You can use .058 wall 1/2 inch tubing. Drilled out .065 is for purists, .058 is fine. Gussets are recommended when the tubes meet the tray at a steep angle, or if you're less than an A+ welder, they provide additional weld area. The complex angles of the 601 mount give it a lot of rigidity, and eliminate the need for the seventh tube. The 7th tube applies more to narrow mounts like a Pietenpol.

Our 601 only has 2 short 18" long pieces of hard line to get around the dual sticks. All the rest is braided stainless. Always use 5052 for aircraft lines. I'm not sure I've ever seen 3003 used for anything other than a vent line.

Subj: New England Corvair College
Date: 2/11/05

Are we any closer to the possibility of a New England Corvair College in the Fall? There's been a good response in the northeast to a suggestion put out on the Matronics lists. Anybody interested on Open E-mail who doesn't subscribe to the Matronics lists?

Thanks, Mark Hodgson, Mass., Pietenpol, #5666
Reply from WW:
We are currently answering your question from Pontiac, Michigan, tonight. We are in the middle of our Midwest Night School Tour. This is our first road trip of 2005. We'll be on the road nearly two weeks. April will bring Sun 'N Fun, where we'll spend 8-9 days meeting builders at the second largest airshow in America. June is five days meeting builders at the SAA gathering in Urbana, Ill. Oshkosh this year falls entirely in July. While we'll spend our traditional three days meeting Pietenpol and Antiques builders at Brodhead and eight days at Oshkosh, the travel back and forth adds a few days on each end. August and September are difficult months to plan in Florida because of hurricane season. In 2004, our hangar had no power for 16 out of 31 days in September, and we did not even receive a direct hit from any of the four hurricanes. There is another four day LSA Expo in the planning stages for October. As a contributing editor for EAA's Light Sport Aircraft magazine, our attendance and support of the event is expected. Just as last year, we are planning a major Corvair College and Fly In at our hangar in November. We always plan to give the Hangar Gang the last two weeks of December off. In 2004, we fell short of this goal, and most of the crew only took Christmas off and worked straight through New Year's Eve. In addition to these major events, I will likely be the guest speaker at a dozen EAA chapter meetings and smaller aviation gatherings. Each of these events, especially the major airshows, require a lot of prep work, usually at least as much time as you spend at the show. Keep in mind, we've never charged for any of our Colleges, and we do not get paid for any of the events I listed. While we do a lot of sales at some airshows, proper etiquette at special events like the SAA gathering and Brodhead dictates a very reserved commercial presence as they're traditionally run as educational rather than consumer events. I use this overview to share with our builders the type of commitment it takes from my crew to share with builders directly the knowledge that we've gained. While we're constantly trying to find new ways like the Night Schools to increase our contact with builders, from this overview it's easy to understand why our schedule is such a challenge. I seriously doubt there's any small company in aviation that could match our efforts with the public. We're sincerely considering when we could add one or two more Colleges to our schedule this year, but they must be fit in with our existing commitments and our need to keep up with the regular expanding orders for the shop without completely burning out my crew. We take all opportunities seriously. We just have to make sure they fit in our schedule.

Subj: Pistons, Rods and Cylinders
Date: 2/10/05

I have received your Conversion Manual and have decided to build the Corvair engine for my powerplant. I have a couple of quick questions. It appears that you pretty much endorse the idea of ordering cylinder and piston kits from the same place in place of say buying parts and running around trying to find a machinist who is interested in doing the Corvair cylinders, etc. My question is how about the con rods too? You recommend not changing the orientation of any of the rods so as not to stress the parts in other than the original way. Has it been your experience that say Clark's or some parts house like this could ensure that the rods will come prepared to use as in their original configuration? If so, I don't see any reason someone would not order the entire set from one supplier with machine work already done, rods installed & balanced. I don't believe you could beat the price even with shipping added, not to mention taking into consideration their expertise. Can you shed some light on this for me? I love the Manual and I'm excited about getting started. I have a perfect core to rebuild and I am well into the wing construction of a Christavia MK1.

Thank you, Chris Barrow, Christavia MK1, Manual #6488, Kernersville, NC

Reply from WW:
The rods from Clark's are a good value in the balanced set. Although it is not stated in their advertising, they are equipped with ARP rod bolts. The premium Corvair rebuilt rods are available from SC Performance. You can call Jeff Ballard (phone number in your Manual), and he will set you up with the finest remanufactured Corvair rods I have personally seen. In addition to the Clark's treatment, they feature 12-point nuts and highly polished beams. We use these in all the high performance engines we build. For typical engines, the Clark's rods and their piston/cylinder kit makes a lot of sense. They're certainly much better quality than typical stuff we've seen done at local machine shops. For guys looking for just a bit more, getting the rods from Jeff and sending your cylinders to Ray Sedman at American Pi is a nice option. These are the two paths that we follow when building an engine. When the rods are remanufactured by these outfits, they are shotpeened. This, in combination with the polished beams, does a lot to remove any built up stress in the rod and minimizes the need to maintain the original orientation.
Subj: Spinner kit question
Date: 2/9/05

First, thanks for all you have done to help us "not so rich folks." Without you and Chris Heintz, a lot of us would not be able to chase our dreams.

I know that you recommend a 13" spinner from Vans aircraft. In checking their Web site, they offer 3 of these spinner kits:
1) C/S-13, for constant speed prop
2) FP-13, for wooden props
3) FP-13 SEN, for the Senenich Metal prop

Which one do we order? Thanks you for your time.

Fritz Gurschick, Maine, scratch building 601XL, Manual #5927
Reply from WW:
Thank you for the kind words. As some of our builders know, I spent my early years in experimental aviation building Lancair IVPs for affluent flyers. Although it was a successful business, the personal reward of providing expensive planes for consumers was predictably nonexistent. Conversely, my drive to perfect and expand our work with Corvairs comes directly from appreciative builders just like you.

The FP-13 spinner is the one that we use. We have a combination front bulkhead and crush plate that works with this spinner when it's used with a Warp Drive propeller. The front bulkhead that comes with the FP-13 is intended for a 4" thick propeller. If you were using it with a 3.5" wood prop, simple half inch spacers would be in order.

Subj: Determining If Core Is Usable
Date: 2/5/05

Having recently purchased my core engine, I am eager to start converting it for my Zodiac XL project. I will also be attending the Midwest Corvair Night School in West Bloomfield, MI, and I can't wait for that opportunity.

When disassembling the core engine, how do I determine if the crankshaft and camshaft have been previously reground, and therefore usable? I can't seem to find information on this in the Conversion Manual or the Open E-mail forum.

Thank you so much for the Open E-mail forum! Your continued dedication to assisting builders and enthusiasts is truly a source of inspiration.

Sincerely, Gregory K. Harris, Lansing, MI, USA, Manual #6145, Zodiac XL
Reply from WW:
We disassemble about 100 core engines a year on average at the hangar. Out of these, perhaps five will have a reground crank in them, maybe one or two will have a non-original cam. So the odds are fairly small that you'll have one of these. When you take your engine apart, you can take the main and rod bearings out and look at the back of them; along with the data stamped in the bearing, you'll see .010 on a .010 under bearing. Stock bearings will either have no measurement or the letters STD on them. We rework a lot of builders' crankshafts every year, and very, very few of the cranks sent in are not good cores. In these cases, we work to find another viable crank, because it's in everyone's interest to have every builder get past a small hurdle smoothly. Looking forward to meeting you in person. If you'd like us to rework your crankshaft, we'll take it back with us and save you the shipping.

Subj: Can I flare my intake?
Date: 2/4/05

Thanks again for coming to see my project and providing helpful advice. Regarding my intake manifold, you will remember that I had the problem of using too small of a pipe at the outlet of my Ellison EFS-3A. The diameter of the manifold is 1.5 inches where the outlet of the EFS-3A is slightly larger. You suggested that I use 2" pipe from the outlet of the carb to the cross member in the "Y" of the manifold. You even showed me how to do it - thanks.

When I spoke with my welder he suggested something that would be easier to do, and I wanted to check with you to see if it is as safe as the the modification you had suggested. His idea was to flare the 1.5" pipe out to the diameter of the outlet of the carb, by using a tapered die to spread out the straight part of the intake. Is this as effective as cutting off the old pipe and welding on a larger one? Also, do you think the strength of the pipe would be compromised?

Thanks in advance for your good advice. I think you and the Hangar Gang are doing a great job.

Phil Maxson, Washington, NJ, 601XL/Corvair

Reply from WW:
I would prefer to see a 1.75" or 2" tube from the carb body to the intake pipe. Some aluminum used to make intake manifolds is 6061-0. This is soft and could be flared. This is what the elbows and bends are made out of. However, much of the straight tubing is 6061-T6, which is way too hard to consider flaring. I think you're better off simply replacing the tube. We made one of these manifolds in the hangar to mount a 35mm Aerocarb (which has the same flange as the Ellison) on a KR intake. The 1.75" tube blended very nicely into the 1.5" main pipe. It was very easy to get a nice fit between the two by using a 1.5" hole saw to cut through the 1.75" pipe. This was the beginning point of a perfect saddle fit.
Subj: New pants?
Date: 2/3/05

Did I read that you now have wheel pants and other good things on your company XL? Would a new photo be possible?

Thank you. Friend Bob
Reply from WW:
Yes, we are installing RV-8 wheelpants on the plane. They're partially fitted, but we haven't had a chance to paint them yet. Our airplane was delivered with full size 6x6 Grove wheels and tires. I like the Grove stuff a lot, but there are very few good wheelpants for 6x6 tires. Gus came up with the idea of mounting 15-600x6 tires on our Grove wheels. This is the tire size from a retractable gear Cessna, like a 172 RG. These tires fit very nicely into the RV-8 wheelpants. This gives us good streamlining without going to the narrower footprint of the 5x5.

Before Christmas, we switched to a taller, narrower landing gear, supplied by Zenith Aircraft. Its increased angle of attack allows the airplane to land and takeoff slower. This gear is only applicable to XL taildraggers. The gear supplied with the tri-gear XLs has very nice geometry and inherently allows for very slow landings. Remember that our XL taildragger was the first, and the revised gear is just part of the fine tuning process. We will update the 601 Web page when we return from our Midwest Night School Tour.

Subj: Insurance
Date: 2/2/05

I see on your Web site that you were talking with the Vice President and Chief Technician of Falcon Insurance. I'm wondering how insurance companies are feeling these days toward your Corvair conversion, and if you have a feel for what kind of difference in rates a person might expect to pay, say comparing to an O-200 installation? In my case we're talking about a Christavia Mk 1 installation. I know it's probably depending a lot on the type of airframe and other factors, but could you say anything at all regarding any progress made on the insurance rate aspect of the Corvair?

Thanks! Mike Sharkey, Ontario, Canada
Reply from WW:
We've been in continuous contact with Falcon on this issue. Although it has been reported that Falcon will not insure some types of automotive powered aircraft, my understanding is that they look at it on a case by case basis. Several Corvair builders, including Mark Jones (KR-2S tri-gear) and Randy Stout (Zenair 601HD tri-gear), have purchased insurance through Falcon for their aircraft. I spent some time speaking in person with Bob Mackey, Falcon VP, at the LSA Expo in Sebring, Fla. In several follow up phone calls, Bob quoted us a very reasonable rate for our Corvair powered 601. The rate was not significantly different than what we pay Falcon to insure Grace's 1946 Taylorcraft. Bob explained that the primary component was the fact that both aircraft are taildraggers. Tricycle geared aircraft owners could expect a lower rate. The policy came with some small stipulations about time in type training that were more than reasonable. If you're interested in insurance, I suggest you contact him directly at EAA HQ for the straight scoop.

Subj: Moroso Follow On
Date: 2/1/05

Hi William,

Following on from your recent notice on which Moroso plug wire kit to buy, I note you state it is an 8 lead kit. Do we not need 9 leads, i.e. 6 to plugs, 1 to cap centre post and 2 between coils and switcher? How do you get around this?

Thanks, John Theron, England, Flitzer Z3 Falke Biplane, Manual No. 5950

Reply from WW:
I more correctly should have said that the number was a V-8 kit, which has 8 plug wires and a coil wire. These kits come with many extra feet of wire, and a multitude of ends. There's enough material to duplicate our standard Dual Ignition installation, which you can see on our Zenair 601.
Subj: Corvair Colleges
Date: 1/31/05

Have you guys decided on what your 2005 Corvair College schedule looks like yet? I know I've bugged you guys quite a bit to consider a Corvair College in Colorado or one of the other Rocky Mountain states. Just wanted to know if all my pestering is finally gonna pay off.

Bill Howerton, Zenair 601, Colorado
Date: 1/31/05

William - Have you set Corvair College schedule yet? I missed the last west coast event but am now ready with cores to machine foreward.

Thanks, Tom, #5518

Reply from WW:
The next event on our schedule is our Midwest Night School Tour. This link contains the information on this new type of event. Unfortunately, this tour will not include Colorado or California. The brief stops for Night Schools will not afford us the time to dig into work on engines, but they are an excellent opportunity for us to answer any technical question in person that may be keeping you from launching your project full steam ahead. By the time we return from this tour, we will barely have six weeks till Sun 'N Fun. This is our largest event of the year, and the effort we put into it exceeds what we do at Oshkosh. We'll have a lot of parts and technical information available at Sun 'N Fun also, and we're trying to get six or eight Corvair powered airplanes to fly in. But, the hectic schedule prevents us from actually doing work on builders' engines. We're currently scheduled to give forums at the SAA gathering in Urbana, Ill., in June, and at Oshkosh. We're looking into the possibility of a June College. There are a number of strong possibilities, but we have not weighed in all the factors. If I could pack more weeks into the year, I'd give more forums all over the country. The constriction is primarily a time issue. We'll keep everybody posted as soon as we find out what we can do. By the way, we don't consider anything you do as nagging, Bill.
Subj: Early Engines
Date: 1/31/05

Hello again, William. Further to an earlier e-mail and your reply, wherein you pointed out that the Corvair engine I had purchased on eBay was a 1963 92HP engine and not suited for AC use, I have since located and purchased a disassembled 110HP engine with the correct block code (RD) and the correct crank code (8409) in addition to many other components. The crankshaft has very light rust on several of the journals which I plan to remove with Flitz metal cleaning compound. Are you familiar with and/or approve of using this product? The cylinders appear to be in perfect condition with no ridge wear and no discernible internal wear marks at all. They may even be new. The cylinder heads shown are not the ones I'll be using. These heads have been left with the person who sold me all this stuff and will have complete valve jobs done by him (in the next couple of weeks) including new valve springs and valves as required.

I have a couple of questions before I proceed: Can I re-use the pushrods, pushrod retainers, rocker arms and rocker balls from the 92HP engine in the 110HP engine? Can I re-use any of the cylinder hold down studs from the 92HP engine in the 110HP engine? Only 2 seem to have thread damage on the head ends. All others look ok and I'd like to leave them in place.

I am planning to be in Florida beginning this coming Wednesday. If I bring the crankshaft, would you be able to look it over and, if satisfactory, would you be able to modify it to accept a Safety Shaft? If you can't accommodate this request on short notice, I completely understand. Just wanted to make sure that what I now have is going to be suitable. Thanks for your help and expertise!

Bernie McLean, Poplar Grove, IL, Manual No.6244
Reply from WW:
Congratulations on finding the correct engine to work with. I reviewed your photos, and the engine does not look nearly as bad as you might think. To remove light rust, have a machine shop polish the crankshaft. I would be very reluctant to use any chemical products on a crankshaft. You never know how it will react with oil, etc. You can use all the valve train parts you mention, but do not re-use the rocker arm balls. You need to get a set of the grooved balls from Clark's. We traditionally use AN-363 and AN-316 nuts in place of the stock nuts. You can use studs from one engine in another; however, many studs in old engines have been overstressed in the disassembly. At times, it's best to just get replacement studs from Clark's. In your photos, I noticed you had the pushrod tubes painted a dark color. Maybe you're using this as primer, but every engine we build has white pushrod tubes to help protect the O-rings from heat.

You can call the hangar line, (386) 478-0396, and make arrangements for a visit Thursdays, Fridays or Saturdays. We're busy, but we'll do anything we can to help out a builder who has shown the initiative to get an engine, and ask questions.

Subj: Kit Choice, Life Saver
Date: 1/31/05

I recently sold my 1955 170 B and I am looking for a kit plane to put together and the 601 XL and the Sonex are the two that have caught my eye. I met you for the first time in Kitplanes magazine. You were discussing your Dual Points Ignition System. I was quite impressed with your statement that 'with a points system you will have advance notice of failure rather than with electronic ignition where there is no warning.' A few months after reading your article I was driving a 1969 Volkswagen with electronic ignition. One minute it was fine and the next it was total silence. My point is that I was so sure that the electronic ignition would never let me down because it was a newer invention so how could it go bad. Do you ever wonder how many lives you may have saved by writing that one article?

I would like to know your thoughts on tri gear vs. tailtragger on the 601XL. I like the taildragger, but I don't want to be intimidated by crosswinds. I have about 500 hours in a Cessna 150 and 150 hours in a 170. I was very comfortable landing in almost any kind of wind in the 150, but I never did have the feeling that I was in control in the 170 when I was on final with a crosswind. Great Web site.

Reply from WW:
Each magazine article I've written over the years has brought us a number of new friends. The same article you read inspired Dave "The Bear" Vargesko, who lives 100 miles south of us, to drive up and introduce himself. Today, he's an integral member of the Hangar Gang, and his Corvair powered Wagabond is nearing completion.

I don't know if I've ever directly prevented anybody from getting seriously hurt, but I'm sure the things that I learned from old timers are the only reason why I'm alive today. I try and pass this wisdom along at every possible opportunity.

The Zenith taildragger is fairly easy to fly as taildraggers go. Our test pilot Gus Warren has flown virtually every classic American light aircraft, and he rates it fairly civilized among its taildragger brethren. This said, there are a number of things to recommend the tri gear:
1. The 601 was designed as a tri gear airplane. As such, it's a well engineered system, not an added on option.
2. The tri gear has no weight penalty, and may actually be slightly lighter than the taildragger.
3. Tricycle gear aircraft will always have lower insurance rates.
4. There will be more days of the year when you will be comfortable flying a tricycle gear.

We have nine aircraft and projects in our hangar right now. Eight of them are taildraggers, and the ninth, Gus' Tri Pacer project, will likely be converted by the time it flys. Working at the airport gives us the option of flying any day the weather is right. Our schedule is more flexible than most people's. For the majority of builders, tricycle gear just makes sense.

Subj: Head Removal
Date: 1/31/05

Well I finally got my hands on a core motor! $150 bought me an assembled *RD motor with the appropriate 9.25:1 heads, cam, crank, oil pump, and distributor (and bell housing of course!). Everything I need and nothing I donít! My first step was to remove the heads. I sprayed some de-locking fluid on the nuts, and after a few hours I tried to twist off the nuts. Two came off, but the other six on one side began to twist the stud out of the case, rather than the nuts themselves. How bad is this?

I know from your Manual that good studs are crucial to avoiding blown head gaskets, and you give a clear explanation on how to helicoil weak stud/case insertions. But how does one assess whether or not the existing stud insertion is good to go, or needs helicoiling? Shall I continue unscrewing the "locked" studs/nuts to remove the heads, then remove the nuts later (perhaps after Iíve soaked them)? Does removing the studs from the case permanently damage the threads and automatically necessitate helicoiling?

P.S. Is it too late to pay up-front and get the intro price for my oil-pump rebuild? I just got the core this weekend, and my oil pump isnít off the case yet. Let me know.

Rob Schaum, Ann Arbor, MI, Manual #6191
Reply from WW:
If you look back through January's Open E-mail, you'll find a good discussion on studs, helicoiling, etc. In your case, I would consider using a chisel to cut the nuts to get them to unscrew. If you can't do this and you unscrew the stud, you'll see in January's Open E-mail a description of how to evaluate the need for helicoiling the hole. In most cases, if the stud turns out clean, it can be replaced after cleaning and re-inserted with Loctite 620.

You can send in your rear oil case with a check for the intro price in the next week or two. You'll find that we're not too particular about exact deadlines on our offers. They're mostly aimed at motivating builders to get going and keep up their building momentum. Success in this game is all about continuous small steps of progress. We encourage this any way we can.

Subj: Piston Clearance
Date: 1/30/05

I have a question about piston clearance. My newly arrived Speed Pro pistons, L2206F .060, call out for .00125 to .00225 clearances with .001 as minimum. This is quite tight to what I am used to for a forged piston clearance. Am I behind the times here? What would be your recommendation?

Roy Szarafinski, #5296
Reply from WW:
The recommendation is based on their use in cars. In aircraft, we have traditionally used them with an initial clearance of 2.5 to 3/1000ths. Most engines that we build utilize cylinders from Clark's. When you order a .030 over piston and a .030 cylinder, the fit between the two is very good right out of the box.

April 2005 Open E-mail Page

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January 2005 Open E-mail Page

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