New to me Corvair engine, need advice on 5th bearing and intake

Hi All,

I am in the planning stage for this CH 650 motor and researching the order I should perform the conversion. I have already talked to WW (I’ll be going the Fly Corvair way) about the heads and case type/numbers, so I know I’m good there. My question to the forum is about the 5th bearing and the head intake. The motor came with a 2006 Corvair Flight Engine manual that gives a good description of each part of the motor; however, it does not speak to the 5th bearing or the intake. Santa will be gifting me the 0100, 0200, 0300 manuals at Christmas, I’ve been a really good boy this year. The crank installed has been magnafluxed and Ion Nitride by the pervious owner, which he believed would suffice. Myself, I believe any mitigation of risk is an absolute necessity. With a quick look at the forward part of the crank, it seems to me that it needs to be extended for the 5th bearing and drilled for the safety shaft. How is this achieved? I was going to do a tear down anyways but does the crank need to be replaced or can the flange but pulled and a new longer flange installed? I’ve read that this can be done in the field but I understand the flange is pressed in place with 20 tons of pressure. I could not find any crank parts, other than the safety shaft, or 5th bearing on Fly Corvair web site. I did read an article by WW to use SPA LLC. Is this a matter of just sending them my crank? I have a feeling that this should be the first mod.

Now the fuel air mixture intake. I have seen pictures with intake tubes welded in place. I have also seen pictures of intake tubes clamped in place. Is there a benefit to either method? What is the purpose of machining and welding the intake to the head? If this needs to be accomplished, then maybe this should be the 2nd mod.

Funds are not unlimited, and I want to perform as much of the work myself as I can. I would appreciate any feedback, lessons learned, or suggestions on making this effort as economical as possible. If there is a check sheet/game plan out there to follow, that would be great.

Thank you in advance.



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You really want to look at Mark Langsford's site.  This page answer's the intake question:

And you'll want to know what he has to say about cranks:

In fact, you might want to read through it all:

Hi Ernest,

The page has been book marked and I'll read through it this weekend. 

All additional comments and suggestions are welcomed.



I am building a 650 and also plan to put a Corvair in my plane.
Your questions are on the right track.
First thing I would suggest is to get all the manuals for the Corvair conversion.
Go to, look for the manuals, order them and read them thouroughly.
A good number of your questions are answered in them.
Second suggestion is, attend a Corvair College.
Even if you are not ready to build your engine you will be able to see others being built, ask questions and get answers.
More than likely there will be planes at the College with Corvair engines in them.
Third suggestion, Attend Zenith's Open House that they have every year.
It's usually in September (this year's just occured). Every year I have attended there were always corvair powered plane there.
Hope these suggestions help.

Hi Earine,

Thank you for the reply. The manuals will be Christmas presents from my family and will be read cover to cover during the holiday. I figured that these two items would be heavy hitters so I'm looking saving up for the cost and lead time. In talking to WW, he stated that a planned Corvair College at Yuma in the spring. I live in Tucson so that is just a short drive. I do want to have the core of the engine ready to attend this college, if it happens.

Please keep the feedback coming.



Thank you Terry. Excellent suggestion on watching the videos. I will be sending the heads to WW's shop to have the welding work accomplish. The guy I purchase the engine from has already overhauled the heads but WW is going to double check everything. I spoke with Dan at SPA and since the crank has already been ion nitride, they do not recommend installing the 2nd gen 5th bearing so I will have to install the 1st gen. That's okay with me, saves about 1K in labor and parts. Thanks again for the YouTube link.


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