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piston ring gaps

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I was wondering, for those of you that have built motors, what size of a piston ring gap you have? I have read different performance books and it seems everyone has a different gap.
I'm figuring it would be somewhere around .016 for a 4.030 bore. Oh, by the way its mainly for the track.
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10,537 Posts
Depends on the type ring and the size and intended use...

I use gapless rings so the specs are different...but I would imagine .012-.016 would be in the ballpark..

Usually the ring package has the mfg's specs right on it.....

The only reason I'd deviate is if I was running a supercharger/turbocharger and/or a custom piston with a thin, high top ring....


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393 Posts
The rule of thumb that I have always heard is to use .004" per inch cylinder bore diameter. So you are right in the ball park.

Jim Gates
72 Mach 1 - 460, C6
65 Olds 4-4-2, 400 ci, 4-sp
71 Dart Swinger 340 - Project in the queue
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