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euro911sc euro911sc is offline
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Join Date: Jul 2005
Location: Hobe Sound, FL
Posts: 3,485
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Thanks for the discussion guys! I believe that Longacre specifically said BDC to prevent the crank from turning when you plug in the air. But, now this issue about what is better, BDC or TDC is interesting.

Wear is highest in the center of the stroke... Seems logical as that is the piston's/ring's highest velocity point. But, what about the pressure at TDC just after ignition. Seems that might cause a lot of wear at the top of the cyl. I just saw a set of cylinders on eBay with a wear spot right at the top that might be evidence of that. Just speculation really.

So where to do the leakdown test? I'd say BDC prior to compression stroke might be easiest. Though TDC is only a few degrees further . Are there any kind of technical differences? I cannot think of any off hand...

Comments?

-Michael
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Old 07-21-2005, 10:02 AM
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