southsidejohnny1954 (12/16/2010)
....but the block bore measures about 3.665" which should be a tired 272 bore.At a 3.665” bore, the cylinder is 0.040” over the standard size. Standard bore size for a 272 is 3.625”. You’ve could have a 0.030” over 272 with 0.010” of wear or could be a true 0.040” over if you are measuring the cylinder at the very top where the top ring doesn’t ride. Don’t be misled by not finding overbore sizes on the piston tops as not all pistons are stamped with bore sizes. And some pistons have their bore sizes stamped with ink if labeled at all and that identifier disappears once the engine has been run. Measuring the bore lower down in the cylinders may give you a more accurate determination of what bore size you’re currently dealing with.
Sonic testing of the block is always recommended when in doubt. Although most 272's will bore out to a 292 bore size, there's not much left after that point for any additional boring. Sonic testing will tell you exactly what is remaining in the block and where any core shift resides.

Lorena, Texas (South of Waco)