William Wynne

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


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December 29, 2004

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Subj: Ignition Questions
Date: 12/29/04

Boy am I glad to see our new Q&A page open. To start this new adventure in getting answers, I found you recommend two different coil setups: a Bosch #00012 with built in resistors and an Accel Super Stock with CR-10? ballast resistors. What is best in your experience? And what condensers P/N?

Next questions: I have restored several old aircraft with unshielded ignitions and built a few VW and Subaru engines up for homebuilts for myself and others and always had the same end result: a good flying aircraft with no radio. Have you or do you plan to address this radio noise problem publicly on your Web site? (I hope so.) I have had a lot of people ask me what to do about it, and I can only tell them to try this or that, but be careful not to create any potential shorts. I plan to get serious about this problem on my Corvair/Wagobond project. Any help you can give me will be greatly appreciated. I want to cut my R&D time as much as I can, but I want to solve the problem for anyone concerned. I hope we can communicate regularly. I would consider your input on this as very valuable. Note: I have a very good friend who has a pacemaker who is afraid to fly in an experimental aircraft because of radio noise interference. He thinks it could stop his heart!! I do not know, but I intend to find out and hopefully solve that problem too. I will keep you posted as yet another R&D project continues.

PS: I received your E-Mail and my Prop Hub Hybrid Studs. Thanks!

Yours truly, Jack Nelson, Manual #5134, Corvair/Wag-o-Bond, 90% finished 90% to go! Ha!Ha!, Livingston, Texas

Reply from WW:
It was good to have you as a guest at Corvair College #8. We flew Accel coils for years, but the 601 and many of our customers' planes use the Bosch coils. I prefer these over the Accel because they do not require external ballast resistors. We've recently started to look at a substitute for the Bosch, an IC675. It is available from any NAPA store. It's lighter and smaller than the Bosch, requires no resistor, and can be mounted at any angle. One of our Canadian friends recommended it, and we've used it on our dynamometer, but have not yet flown it, although I have little doubt it will be our new choice. The condensers we use with any coil are the standard NAPA condenser for the Corvair. You'll need two; one for each coil.

We have a King radio in the 601. We've used handhelds in all our previous airplanes. The majority of our customers' aircraft have radios. I have absolutely no reports of ignition noise on any of these radios with our system. I credit this mostly to the spiral wound wires we recommend in the Conversion Manual, and the fact that points ignition systems traditionally make less radio interference than most types of electronic ignition. I would not be concerned about using a radio with our system. Experience has shown it's not an issue. You'll need to get in touch with some really electronically savvy people to evaluate concerns of your friend's pacemaker vs. aircraft equipment. Sounds like an interesting project, though.

Subj: Cores
Date: 12/29/04

I have access to a fellow with lots of Corvair engines for sale. Good condition, but none of them are assembled. I picked up enough parts to make 2 engines. Most parts are pretty easy to say yes or no on. And some I just got for cores anyway. But what's the deal with engine cases? Are they all pretty much the same thing? I can't see any differences visually between the various years. I thought maybe the crankshaft holes might vary over the years at least. I am glad I got 2 of everything since one case has an extra oil galley return hole drilled in an odd place. I would weld it closed with my Tig, but I keep blowing the house circuit breaker at that high an amperage. Woohoo!

Mike Studer, Cassutt, Newark, CA
Reply from WW:
All Corvair engine cases have most of the important dimensions in common. But, the main difference is that 1960-63 cases will not allow the longer stroke of the 1964-69 crankshaft without significant machining. Thus, your primary case candidates are the 1965-69 engines, and the 1964s. The 1965-69s are easy to id because 99% of them have an "R" for the second to last digit in the engine case code. For example, RR, RD, RA, RH. The 1964s are easy to identify if you know what to look for. The '64's case code will not assure you of identifying it. There are 1964 YN engines which have the long stroke crank and the internal clearance for it, and there are 1961-63 YNs which are short stroke engines which would require machining for long stroke crank clearance. In the land of Corvairs, a long stroke case is referred to as a "relieved" case. Anyone who knows Corvair engines can show you the clearancing done by the factory inside the case. There are good drawings of this in The Corvair Junkyard Primer, a booklet available from Clark's Corvairs.

Tig welders draw an impressive amount of current when set on AC. I tripped the breaker at our old hangar a zillion times. The breaker box was all the way at the end of the hangar row. The experience was a real vocabulary expander. Our new hangar has a 100 amp circuit for the welder. Be cautious about excessive welding on the case. You want to avoid having any type of slag enter the oil system.

Subj: West Coast Corvair College
Date: 12/28/04

I heard a rumor that you may be coming to Southern California to present a Corvair College this spring. Might that be happening at the EAA hangar at Compton Airport? There are a couple of us (likely many more) who would attend from the Left Coast.

Warm regards, Randy Stein
Reply from WW:
We had a great time at Corvair College #5 in Hanford, Calif., in January 2004. We've given a lot of thought to returning, even for a brief one or two day event. I lived in California many years ago, and it only took our brief visit to remind me that the work hard, play hard motto was probably invented there. Our learn, build and fly motto and enthusiastic approach plays well with builders of high initiative. Although it's a long way, it's never too far to travel to meet more builders who feel this way. We're going to publish our 2005 season schedule on our Web site about mid-January. We're strongly considering a West Coast event. We'll let everybody know.

Subj: Valve Job
Date: 12/28/04

I'm doing the valves on those heads you welded up for me at Corvair College #8. I've got stainless exhausts but can't find the intakes. Can I use the stock or "tuftrited" ones? Also, couldn't find a part number for the valve springs in the Manual.

Great idea going to this "Open" format.

Lanny Bissell, South Carolina, Manual 6143

Reply from WW:
We have hundreds of flight hours on both stock valves and aftermarket stainless valves. They both gave good service. We use stainless steel intake and exhaust valves in engines which we produce because I know that they're better than stock valves, at a modest increase in cost. The exhaust valves in the engine work at a higher temperature than the intakes. If I were going to choose intake or exhaust, I would put the stainless valves in the exhaust. If you still would like stainless intakes but can't find them, let us know. We can probably find a set for you. The TRW valve spring part number is included in the back of the Manual. It's good, but lately we've had a lot of success with springs from Jeff Ballard at SC Performance. His number is also in your Manual in the 3100cc section. We use digital scales to carefully test every valve spring going into an engine, and the ones from Jeff are very consistent and are exactly the rate we like for the OT-10 cam. Additoinally, they're not very expensive.

Subj: Can I Mix Case Halves?
Date: 12/28/04

I have two engines that I am disassembling with hopes of building one good engine for my 601XL. Neither engine has a pair of perfect case halves. In the first engine, one half has good studs but on the other half I was forced to cut or remove 4 studs. The second engine has two rods (#5 and #6) broken at the crank end. As the engine self-destructed something broke a finger-sized hole opposite cylinder #6 in the "odd" case half (cylinders 1-3-5). Both engines are "RH" blocks (both from 1965, I believe).

So what is the safest route - repair the cut/removed studs and keep the original pair together or take the good halves from each engine?

Craig Payne, Park City, UT, Manual #6154

Reply from WW:
It is bad practice to mix case halves. 1960s machining technology leads me to believe that the case halves are not interchangable with each other. If you did assemble it, and it rotated, I do not believe that the engine would be long lived. You would be far better off making the repairs to keep the original case halves together. Remember that a pair of cases for a Corvair is never worth more than $100. So, if it looks like heroic measures would be required, simply get another case. In all my years of working with Corvair engines, I've seen just a single car engine, which apparently ran, that was made from case halves of two different years of Corvairs. I would not follow this example. I would always use a set of case halves that left the factory as a machined pair. This advice is not just for Corvairs, it's standard practice on Continentals and Lycomings also.

Subj: Motor Mount Bolts
Date: 12/27/04

I have the WW Motor Mount on my 601XL. The motor mount bolts are from Zenith and were produced for the O-235 engine. When the mount is placed on the bolts, the spindles of the mount are short enough that approx. 5/8" of non-threaded bolt protrudes beyond the spindles. What is the recommended method to fill this difference so that the nuts can draw up properly? I noticed on the WW 601 that the bolt heads are resting on the spindles and the nut is on the inside of the firewall. In the Zenith motor mount bolts, they are welded to brackets that attach to the upper longerons and the nuts are on the engine side of the firewall.

Gary Ray, West Bloomfield, MI, 601XL
Reply from WW:
The Motor Mount on our own 601 is one of a kind. Although it's dimensionally identical to the ones we produce in terms of engine location, the attach points to the firewall are reversed from our production motor mounts. The spools, the part of the motor mount through which the bolt passes, are 38mm long. This is the same as the motor mount shown on the 601 plans page 6Y-E-2. This page contains the drawing of the O-235 Dynafocal mount. You can compare the length of your studs to these studs. There's some discrepancy with your mounting bolts, but it's not a big issue. Either you could use shorter bolts, or we'll machine you a set of spacers to go between the nut and the motor mount.

Subj: Fuel Pump Bushing
Date: 12/26/04

I just assembled my engine with the rear case mounted. I left the fuel pump bushing in. Can I either pull it out, or stuff something in it to catch the chips and cut it off?

Thank you, John Monday, KR-2S, Laguna Beach, CA
Reply from WW:
I pulled one of these out of an assembled engine just today. I used the threaded rod and tube style puller. A 3/8-16 rod will slide down the middle of the guide. Rotate the engine so that the eccentric is in a position to give you the most clearance below the guide. A standard nut can be ground down to an outside diameter smaller than the OD of the guide. Using some very long pliers, you can hold this below the guide and thread the rod into it. Playing a propane torch over the guide area for one minute will allow the aluminum to expand and make drawing the guide out easier. The alternative, as you mentioned, is cutting it off. Packing the area with greasy rags to catch the chips and then using a Shop Vac to clean up all the chips after cutting, before the rags are removed, is effective if done carefully. Be very cautious not to nick the gasket surface. More information on this can be found on the Oil System Page.

P.S. A follow on to your earlier question about vacuum pumps. Vince and Louis, the 601 builders/airline pilots from St. Louis, recently showed me a completely electronic attitude indicator. It was part of a glass panel display that they're planning on installing in their 601. When they showed me the price, it struck me that the end of the vacuum pump and mechanical attitude gyro era of experimental airplanes was coming to a close.

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