New builder, question on long term part availablity


Below is a letter from a new builder out west. The original letter was longer and split his thoughts between two topics. For the sake of covering just one of them here, I pulled out the paragraphs on the other topic. As anyone who has written in knows, I don’t edit or abbreviate things that builders write in, so It is important that people reading realize that this is a special case letter, where splitting out this half serves a purpose of covering this topic.  If I do more than correct a spelling in a builder’s letter, I will say so, otherwise, printed as received.

The original letter is in blue. My reply is in green. I stuck it in the middle of the letter to address his questions as they come up, it makes it easier to read this way. I picked up on his letter because the questions in it are frequently asked by new builders, and covering them here allows a lot of people to gain some insight.-ww


A few months ago I sent you a letter regarding the difficulty I was having in locating a Corvair Engine Core on the West Coast. A few words from you after you published my letter on your site put me in touch with a number of Corvair builders including Gary Boothe. After a series of false starts, it looks like I have located a couple of good cores in Medford, Oregon. I am headed there this week with your manual to verify the engine information and hopefully bring home to Redding, Ca,. two late-model cores that have not been opened in the past. Thanks for your assistance.

William,  really need your “leadership” when it comes to building an aircraft engine from a fifty year old “boxer engine” built by a car manufacturer who never before or after built anything like it again!!!

Doug, you are correct externally, the Corvair is GM’s only air-cooled engine. But once you dig into the engine some, you will see that the engine is really a typical GM product. Al Kolbe lead the design team that did the Small Block V-8 just before he did the same for the Corvair. Internally there is a way more than you would think in common between these engines. Not just things like using the same lifter, and rocker design, but also proportions like the Corvairs rod being a scale model of a 283/327 rod, the engine having the exact same oil pump cross-section, distributor shaft size and design, etc. The material and way the cranks were made then were the same. If you look at GM’s two other master pieces of the same era, the straight six and the big block, there are also many things in common. Most of the ignition system is the same as the straight six, the splayed valve design also is on the Big Block. I owned and built a number of each of these for classic GM engines. They are all very much from the same gene pool. This is why it is a great joke when some idiot tries to claim that the engine was designed overseas or it was made by a helicopter company. Those people are just BS artists.

There are a number of circumstances that have changed since you published your manual. What about addressing those issues? How about the diminishing cores that are still usable? Can the original molds for the cores be purchased from GM or was it a “Lost Cast” process?? Can we be confident that these engines can be rebuilt in years to come? What about the crankshaft issues that creep in at about 300 hours even with a fifth bearing?

The website is the main way that the information stays really crisp. This website got more words on it in the last 8 months than the manual has in it. You still need both, but the freshest stuff is obviously going to be here. The architecture of the conversion manual is the oldest of things we have in print. The Zenith manual and the Flight ops manual are much newer, we still update the manual with each new printing. Some people think of it as older, but when a new guy asks a question, 8 times out of 10, the answer is in the manual, he just missed it on first read.

There really is no core issue. Have you run an ad on Craigslist in the “Wanted” section? If you wait to read things that are listed, you are doing it the passive way, and it takes a lot more time.  There is no shortage of cores, it’s a myth that it easy to think when you are getting started. Lycoming built 270,000 engines total in their first 75 years in business. This is roughly the number of Corvairs GM built in 1964. Finding a Corvair is not hard at all compared to finding an O-200 near you. They built less than 40,000 O-200s. Which do you think there are more of 50 years later?

The molds are said to exist, but they are not needed. Dan Weseman has already looked at building every part in the engine new and he thinks it is do-able. Lets look at what is already made new: Cranks, Rods, pistons, cylinders, pushrods, pushrod tubes, Valves, guides, seats, springs, all kinds of gears for the cam/crank/distributor, etc. So what part are you concerned about? Right now, today, you can build an engine from a case, an oil pump housing and two head cores. Dan knows a lot about modern manufacturing in metal, and he doesn’t think those last three parts are that tough. Keep in mind, Ron Lendon has an original set op manufacturing drawing for the whole engine. I do not know of any other conversion engine people are putting in a plane where clever entrepreneurial builders have access to the drawings.

Your last comment “What about the crankshaft issues that creep in at about 300 hours even with a fifth bearing?” Touches a nerve with me. Maybe you just typed that in wrong, but if anyone said something you about 5th bearing engine having some “issue”, then I need the person’s name and number, and they are going to have an unpleasant phone call from me. That is another pile of BS. The only crank that has ever broken with a 5th bearing was Mark Langfords. and it broke at the other end of the crank.  The 5th bearing has conclusively stopped crank issues, period. We are now six years into engines having 5th bearings. They work. When Mark broke his at 450 hours, he honestly felt that his aircraft was the harbinger of some issue. Yet in the 18 months since, no other engine with a 5th bearing has broken a crank. Some engines are now approaching 700 hours on a bearing, many are well beyond 300 hours. Engines have flown more than 1,500 hours without one, there is no reason to suggest that engine with a bearing are only going to last 1/5 of that. Again, if there is someone spreading that story, I want to know who it is.

You have really touched on something with the new “parts catalogue” numbering system. William, I sent you an earlier letter asking you to review a list of items I was expecting to purchase in order to build a Corvair Engine. Although you did not respond to that letter, your new catalogue will help me make the right choices.

That was the intent of the new numbering system. As you can imagine, with several hundred active builders, it is hard for me to look at every list that builders compile, especially lists from new guys who are yet to get a core and tear it apart. A number of people a month send me things on spreadsheets to study. I understand that this is something that guys who work in modern business do, but it isn’t a good use of my time. First 4 out of 5 of the emails require me to find some other software just to open it. (I rarely bother) Not a big deal to office guys. Come to a college and I will hand you a tool like a differential compression tester and ask that you test all six cylinders and give an analysis in 5 to 6 minutes. That task isn’t a big deal in my ‘office’ for me, but I am reasonable and don’t expect builders to perform like a professional A&P. Besides, I can teach any person with a room temp IQ how to build a good Flight engine much faster than the best computer guru could teach me how to work with spread sheets and find software applications. Computers are part of the craft that many builders do for a living. But lets keep in mind that our goal is to build engines and planes and go flying for real.

Let’s talk about what it will take to keep the movement going forward while the product continues to improve.”

I hate to point this out, but I could get eaten by an alligator, and the world of Corvairs would advance just fine. I am planning on being here to share it with everyone and have fun right beside you, but it is very important to understand that the Corvair can not be stopped nor crippled by the loss of one person, even me. In the 25 years I have been doing this, I have seen many companies get taken right under by the principle buying the farm, or even just quitting. The business model of those people was all about proprietary stuff and secret ingredients. We are just the reverse, I am teaching people how to be independent every day. I am not keeping the secret at all. Many other engine companies, even ones that had real promising stuff, went under before they could build production levels of hardware. We are not in this position at all; 1.7 millon Corvairs have already been made, they are distributed around the country, and time has gone by so they are devalued to core pricing. I am slow but not stupid, I knew this going in 25 years ago, and I was very glad to have an engine that already had a very long production run. There are only 35,000 experimental aircraft total.  98% of Corvairs could have been scrapped and we would still have 35,000 cores left to work with. It just isn’t an issue.-ww

About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at and in more than 50 magazine articles.

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