I have been trying to do a budget rebuild on the 235 in my 55.2. Just wanted to replace rings, rod and main bearings, valve seals, oil pump and gaskets involved. Upon removing the oil pan and taking the pistons out, I luckily noticed the pistons had cracked along the edge near the wrist pin hole, but on the round edge. Each piston was cracked in same spot. Going to have to order new pistons on Monday morn. What would have made the pistons crack here, or at all? I did get the motor to start before I disassemble it, though it turned over hard. I will try to post a pic. Though it looks like the piston is chipped, it IS actually a crack that extends into the rough casting.
cracked piston here is another shot...
second pic
