I have 3 good pistons from a ZC laying around, the 4th, however is slightly mushroomed from when the rod snapped. I would think they are an alloy, so I shouldn't have to worry if I tossed them on the engine lathe at school and trimmed them down. Would I be risking anything if I just cut the edges at an angle? I know they need to stay pretty well balanced. I've also thought about knocking down the mushrooming on the bad one, and leaving the rest alone.
Any opinions, or should I just look for a better set of pistons?
-edit- btw, I'm looking at using these in a D15 block, possibly with a Y8 head. ~11-11.5:1 compression
I would be very careful with the internals. If you shave any material off, it's going to be off balance. Best thing to do would be look for someone else with a blown ZC with a couple good pistons and get one from that.
Actually, I recall reading that they're ballanced as sets. Each piston is weighed after being made, assigned a letter and placed in a set of 4 with other similar pistons. I immagine the same thing is done with the connecting rods... maybe rod and piston sets are matched depeding on weight as well?