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Having run S/SS for several years I know and have formed my own 'dimples' when the P/V clearances were TOO close (.040"). In stock, we take lots of chances because we're stuck with non-reliefed/flat top pistons and quite often, run-what-you-brung situations with our engine parameters, which can end up with disastrous results (getting the aforementioned 'dimples'/ forging our own reliefs or worse, ouch). Nonetheless, a good rule-of-thumb is .080" piston to valve at the closest point. Some say .080" intake, .100" exhaust, so if you have the option to modify/machine the tops for bigger/deeper pockets, do it! I've also talked to a few engine shops that state absolute minimum piston to head clearance should be .050" in a steel rod engine. I've run as close as .037" with a wobbly .008" skirt clearance to boot without crashing. So...what is the 'correct' clearance? Whatever you can get away with without catastrophic engine damage/failure. Just be aware that the results could be less than positive should you have inaccurate measuring techniques or your choice of clearances be inadequate!



True enough. Why would ANYONE try this on a non class style motor? They must have money and time on there hands. Nothin more fun then dropping a valve, well maybe kickin a rod.
Doug