I have been in contact with Mark at Clark's and they are concerned the fifth bearing just may be the culprit. Here are some comments below.
Mark Jones (N886MJ) Stevens Point, WI Web page: www.flykr2s.com e-mail: flyk...@charter.net ----- Original Message ----- From: Clarks Corvair Parts Inc To: Mark Jones Sent: Wednesday, November 05, 2008 12:34 PM Subject: Re: failed cam Your cam gear was installed by us the way that we have been doing these for the last 30 years, allowing the thrust washer just enough clearance to spin as it should. William has a different opinion on this. We have been working on Corvairs exclusively for over 35 years and this is our stance on this. If you press the gears on tight the way William prefers, then yes it will cause some deflection, yours was not done this way. That is not the reason that we do them that way, we do them this way because it is correct. In any case it is not the reason for your failure, since we installed the gear. In thinking more about the 5th bearing, while it may be making things feel better, the vibration and movement in the crank is probably just being moved down the crank and ending up at the gears. In over 35 years of dealing with corvairs, we have only ever seen maybe 2-3 cranks ever break. The aircraft motors have already seen more than this, which tells me that whatever your props are doing to the crank is beyond what it was designed to do for extended periods of time. I know none of this is a good answer for you, but is just food for thought in determining what to do next. Please let me know what else you find after the heads are pulled, thanks, Mark Mark, Here is something that may be of interest to you. This was taken off William Wynne's web site: Technical News You Can Use Above are two cam thrust washers for a Corvair. On the lathe, I've cut a slight bevel to provide clearance on the side of the washer that touches the cam. My research into building Corvair engines is continuous and ongoing. The unbeveled washer is an aftermarket part supplied by several of the Corvair parts houses. When pressing on a new cam gear, this will make the cam gear walk slightly out of square at the last moment. After years of installing countless cam gears without problem, we'd recently had trouble getting several of them to seat on their cams and hold tight their washers. Ignoring this problem, people selling cams with gears on had been leaving the washer loose as a really poor fix. It took a while to determine what was causing this issue, but a slight relief on the washer makes the difference. Mark Jones (N886MJ) Stevens Point, WI Web page: www.flykr2s.com e-mail: flyk...@charter.net
