[Sharps40]

I'll get a look at the Rocket later. My guess is the cylinder is scarred given the jar fulla steel balls noises!

Our guess about what happened? Prolly come combination of reutilization of parts during the rebuild. Its normal to reuse things like keepers, valves, rocker arms, cams, etc. And on an old motor, reuse of high mileage parts compounds the problems of an already 40 + year old piece of metal. And, if it was a home rebuild/small shop rebuild, prolly no magnaflux/die penetratant tests to weed out obviously defective stuff. It happens.

I've had two economy rebuilt engines, this on and a Flat Head Dodge 217, both failed.

Time for a crate motor with warranty I think....250 L6 for sure!