Hi Max,

Hate to be mentioning names, but I had heard of Mark L having a couple broken cranks. If I recall, Mark might be the one I heard of that tended to push his Corvair to the limits, which might account for multiple(?) crank failures. Not positive but believe many crank failures I heard of happened in front of or in the front (forward) throw of the crank. I'm pretty sure one having the nitrided crank and fifth bearing cracked (causing forced landing) further back in the crank.

Friend of mine has one and he told me they found some aluminum in a valve cover and is suspecting it may have come from the cam gear. This engine has not been tore apart yet, so time will tell.

I know of another that had one cam gear go out and at least one crank let go. This one has been rebuilt, 5th bearing added and is flying again, with out issues.

I have to say, if I hadn't already, all these Corvairs I know of have been in the KRs. It was also suggested to me that it might be the shorter props and higher RPMs contributing to those failures.

I'm no expert on these engines. The one I put together (2 or 3) times has not broke a crank. I installed the Dan Wesseman 5th bearing on it as well. This is the one that has found aluminum in the valve cover and is suspecting cam gear.

I also have most of the parts needed to put one of these together for a plane project my son and I have. It will be a much slower plane and longer prop. I just a bit leery on going forward with this engine, given what I've seen in the KRs, but we're a ways off and will keep an eye open for new info. The KR I've worked on has the sweetest, most powerful sounding small AC engine imaginable. Sounds like a HEMI idling, waiting for the lights to go green and tear down the 1/4 mile at WIR. Full power kinda makes your heart pound. Maybe the new crank is all that needed.

Here's a couple good reads.

http://www.n56ml.com/corvair/break3/
http://www.homebuiltairplanes.com/fo...k-failure.html
http://www.zenith.aero/forum/topics/...corvair-engine