Packard Forum Index » V-8 (1955-56)

If I have pistons that are stamped .030, what rings should I order? My initial reaction is that I should get .030 ('30 over) rings, but if the block has been bored and the pistons are oversized, wouldn't the rings be different than using oversized rings on a standard piston?
Thanks,
John

Oversize rings should never be used on/with standard bore pistons. Wherever you read that, burn that book!

Replacement pistons are stamped with the oversize; the ring package is marked with the corresponding oversize.

The piston skirt is measured with a micrometer. The cylinder is bored and honed .001" - .003" larger to fit that piston.

The rings are inserted into the bore and the end gap is measured. If the gap is less than specified, the ring ends are filed to fit.

jack vines

Thanks Jack. I figured that was the case, but couldn't kick that memory of installing oversized rings onto a standard piston to account for worn cylinders. Of course, that was almost 60 years ago!

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Your memory is sort-of correct, but as my mother said many times:

"Just because you can doesn't mean you should."

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No, it was the same rings, whether a patch job or a proper rebore.

However, yes, back in the bad old days, when Studebakers and Packards were orphan cars on their last stop before the junk yard, owners would patch them. The pistons were knurled, cylinders honed, .010" oversize rings were installed. The result slapped and smoked for another few thousand miles.

For really worn pistons and really cheap owners, there are tool kits with a cutter to square up worn ring grooves and then a thin spacer, like one used on the oil rings, was fitted under the new rings.

jack vines