Replies to This Discussion

Permalink Reply by Dale Walters on June 13, 2020 at 3:28pm

Yes I had set the timing at full static RPM, and yes I do have a mop manual.

The issue is that the distributor that I purchased from him, instead of advancing 20 degrees as it was supposed to, advanced 30°.

So by setting the initial timing to 8 degrees, total advance became 38°, much too much.

If I would have tried to allow for the excessive total advance, it would not have idle correctly

The fix was to get a new distributor

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Permalink Reply by Ken Pavlou on June 19, 2020 at 1:19pm

Dale,

This makes no sense.  Even if the timing was 38 degrees the corvair would still spin up to full static. The old specs called for 32 degrees of advance and I doubt going 6 more degrees would inhibit RPMs. If anything it would cause the engine to turn more RPM’s. 

I assume that if you thought the problem was the distributer you returned it to William to have it checked out. What did William have to say?

-Ken

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Permalink Reply by Ernest Christley on June 19, 2020 at 1:44pm

Not necessarily.  If you advance to far, you get the piston pushing against an expanding combustion event.  This isn't often seen, because the "pre downstroke" pressure progresses very quickly  to destroying a cylinder.  I fully suspect that if Dale had continued the run, he would have had the opportunity to replace a piston.  I mistakenly set my timing closer to 40, and I got that opportunity.

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Permalink Reply by Ken Pavlou on June 19, 2020 at 2:27pm

I understand what you’re saying Earnest, and you’re right, you certainly don’t want to over advance for the reasons you mentioned, however in early testing corvairs were actually flown with 38 degrees of advance. Again, i’m not saying it’s ok to run at that those numbers, just that 38 degrees of advance wouldn’t necessarily cause what Dale was experiencing. Another confusing point is Dale said he set the timing with a light to 28 degrees. As you already know, the timing is set at full throttle which means the distributor has gone to full advance. If the advance was set to 28 degrees at full throttle with a timing light and the distributor had 30 degrees of advance in you would expect the timing to retard to 2 degrees after TDC when the engine is brought back down to idle. This would cause hard starting and idle issues not static RPM issues. 

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Permalink Reply by Dale Walters on June 29, 2020 at 10:03am

I understand what you're saying about still getting full static at 38 degrees, but that's not what I experienced.  

After installing the distributor from WW, I was getting 300rpm less.  Despite various troubleshooting efforts under the direction of William, I was still getting 300rpm.  As soon as I installed a second distributor, I started getting the correct static.  Putting the original distributor on a distributor machine showed it was advancing 30 degrees instead of the 20 it was supposed to.

"If the advance was set to 28 degrees at full throttle with a timing light and the distributor had 30 degrees of advance in you would expect the timing to retard to 2 degrees after TDC when the engine is brought back down to idle"

Yes, that's exactly what happened.  Trying to set the distributor to *only* 28 degrees full advance caused the timing to be 2 degrees after TDC... which caused hard starting issues.

End result:  The distributor I was originally sent was defective... installing a different distributor corrected the issue

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Permalink Reply by David Banahan on July 20, 2020 at 10:44am

You may have problems with your engine and I don't think that is the problem with low RPMs.  Try adjusting the prop pitch to a lesser angle say about 8.5 degrees.  As I understand it in WW's new manual you should get a minimum of 2850 RPM.

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Permalink Reply by Ian Robb on July 20, 2020 at 2:22pm

Dale posted on June 29th, that the distributor was faulty and a new one solved the problem. 

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