Originally Posted by cobalt327
There are KB hypereutectic pistons that need more top ring gap than 'normal'. If you have a set of those in it and the gaps were set the way a cast piston is usually gapped...
Im with Cobalt. I remember getting the KB Hypers years ago and they had a little paper flyer in the box that specified the 'odd' gap.
My friend bought some of the same pistons via the internets; no paperwork. He set up a conventional ring pack and cracked or distorted the ring lands in all 8 pistons.
Why only 4 pistons though. You may have several problems manifesting themselves here. Did you check for interference with the valves? Was the block decked? Heads shaved? What is your compression ratio and what fuel are you running. What are you using for timing?
you might want to post your assembly procedure for us to look at. Not to judge, sometimes we miss a step.