For the record, the # 1 piston:
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...was cleaned after the head was off. There is no way that a piston would remain this clean after the engine has ran awhile.
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We cleaned it to do a rudimentary measurement of the deck clearance. I don't recall how far below deck these were and I'm not sure of how big the dish is. These were rated at 9.0 to 1 though, right? The smaller "Magnum" series combustion chambers helped out with the compression ratio.