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Piston ring groove checking

Posted: Fri Jun 23, 2006 6:58 pm
by Guy Croft
Measuring ring side clearance - use a new ring and a feeler gauge. Typically rings will need at least 0.001" (1 thou in GC slang). Too tight and they could well seize or 'spall' as some piston manufacturers call it.
If the grooves are a too tight, you can relieve them on the upper face of the ring groove by machining, of course it hsa to be done with great precision, but I have done done successfully many times. The upper face is not a functional sealing face, so if the contour is in parallel to the same high degree as when they were made, it's not a huge issue. Is it a desirable op? NO, but if the maker won't accept liability for them, it's better than junking them.