[GaryU.]

Given that this engine was living in a 1939 Coupe in Minnesota it is not surprising that probably during an engine rebuild a block heater was installed. Never have seen one in a flathead before but maybe not that uncommon in the Northern climes? Just a bit of carbon buildup on the pistons(LOL), smooth bores with a tiny ridge at top. No stamp on pistons with an oversize, haven't measured bore yet. Been in a corner of the garage for 4 plus years but ran when pulled! I did hear it run with a rigged up earlier distributor while it was still installed in car. Winter project time is here.