Basically he has burnt up two pistons. side scuffing transferring piston material to the cylinder wall. This is on the thrust side. He keeps buying pistons and cylinders separately will no knowledge of PtoC clearance. Also piston pin location is different and port opening on the pistons each is different. I know, nothing is correct here and basically he has a basket of mismatched parts. On the piston scuffing I told him it is either a clearance issue or lack of oil. Could be the HC heads he keeps putting on or perhaps the big ass carbs he sticks on. His knowledge of gas engines is zero. Any thoughts with this? What clearance should he be looking for on piston to cylinder? Then along with this he has 2 blocks and four cranks. All 4 cranks have a different length rod and I will not even try to figure out the correct piston for each rod. 6 pistons to choose from so far and all have a different fuel intake port and piston pin location. That is what you get when you just order a piston without knowing the specifications dictate piston type. With everything wrong so far what are the thoughts on scuffing the crap out of the pistons? I think that the boxes of parts should all be tossed and he should buy a new engine, one that is set up and stop his tearing them apart. OK he needs to learn, where does he start, what does he read from where,?