Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Piston /wall clearence
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Old 10-28-2002, 04:08 PM
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are you sure its twenty thousants, that is wwwwway to much clearance. try .002 or two thousants. which is not enough for forged pistons. the actual piston to wall clearance depends on the design of the piston, the material its made of, cast or forged or hypereutectic cast. the bore size and what its going to be used for. consult the pistons manufacturer for correct wall clearance.. i'm always seeing keith black pistons with the top ring lands pulled off and the owner cussing the piston manufacturer as bad pistons, but they didn't read the basic instructions included in the set that says hyper pistons have to have different clearances and way more ring end gap, the top ring butts from the heat transfer and away goes the top of the piston. most forgings in a 4" bore are .0035 + due to the way the piston expands. way back in the old days we ran them at .008+ and thought nothing of it but materials are different now and ring tech is better.
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