On 9/12/2012 8:24 AM, EDWARD BARNARD wrote:
> Group / Glen: At the risk of opening a can of worms similar to the "to torque
> plate or not to torque plate" argument, I have a question for the group. I
> have a certain interest in Greg and Bob's plight since I assembled the first
> engine that failed. Clearances were .005" on all pistons to cylinder walls,
> and we assumed that the failure was that the machinist I use didn't properly
> use the torque plate I provide him.
> When their machinists work failed in a similar manner this weekend it opens up
> the failure analysis beyond one persons lack of attention. At the track I put
> forth the theory of possible heat in the number 4 cylinder. This block has
> been vatted and thoroughly cleaned multiple times so I'd like to rule that
> failure out.
>
One of those unaccounted-for variables might be individual variations in
the blocks and heads used. I think the procedure of blocking flow out of
the forward cylinders to increase flow through the rears has some merit,
but consider this: what if there were a mismatch of _both_ head and
block to the head gasket at that cylinder, i.e., a coolant opening in
the head blocked the gasket opening area on one side, while a mismatch
to the block hindered flow on the other? The net effect would be
greatly attenuated flow out of the block on at least one side of the
cylinder. The other variable could be a casting anomaly inside the head
at that cylinder or just forward of it.
Those are the sort of things that tend to go unnoticed during machining
and/or rebuilding, but can have rather profound effects on performance,
and can be a devil to find without hard data on temperature variations.
Cheers.
--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking distance....
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