Thread: Insert bearings
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Old 07-05-2020, 05:50 PM   #62
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Join Date: Jun 2014
Location: Melbourne, Australia
Posts: 5,173
Default Re: Insert bearings

Originally Posted by Dave in MN View Post
Synchro, Is it possible for that the timing was a it too far advanced for the load at times? It only takes a short run with took much advance to damage a bearing. Would you be able to share some photos of the insert shell? Thanks.
I'll ask my grandkids to help me get some pictures up.
Your question about timing might be on the money but not because I advanced it too far but because it developed the Model A 3/4 crossfire and it took me a while to find it. The symptoms were pinging at any time -- no relationship to load or advance or speed or octane of the fuel etc. Then, a few miles down the road I'd come to a hill and the car would fly up it with no sign of trouble - the very time you'd expect it to ping. The latter observation tells me that the timing was good. There is another complication here though. If there is a cross fire, number 3 fires at the same time as #4. The firing order is 1,2,4,3 which means that when #4 fires, #3 is at the beginning of its compression stroke and that would cause mayhem in there. When #3 fires, #4 is at the bottom of its power stroke which would be a bit of a non event. Clearly, it is the middle main bearing that would get the harder time of it, not the rear one. The middle main was fine but it is pressure fed at 25 psi. Was it protected by the pressurised oil feed even though it is much smaller than the rear (gravity fed) bearing?
It is no burden to carry a little extra knowledge.

Last edited by Synchro909; 07-05-2020 at 06:24 PM.
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