The deck height is at .017 using a copper head gasket that compresses down to .020 which sets the head clearance at .037. The top ring stops at approximately .125 from the lowest point of the relieving but the piston does go up above the relived area a bit. On the area of the piston that goes up above the relieved area there are scores on the set that ran for 2,000 miles and on a set that were run for 10,000 miles, that area has scores and definite heat damage. I thought the damage on the set that ran 10,000 was caused by detonation that was going on at the end of last year but not sure now. It looks as though that area on the piston is either getting extremely hot and expanding enough (unlikely) to hit the cylinder and getting scraped as it passes the relieved area or something is pushing the piston over to the valve side of the cylinder. Whatever the cause it is defiantly hitting. On the front cylinder (the one that did not have a piston problem) there is scoring on the right (valve) side of the cylinder and little if any anywhere else. The scoring is in the entire ring travel area on the right side. Ring gap was correct, rods are straight and in the center, flywheel end play is OK.
Would it be a good idea to chamfer the top of the piston starting just below the depth of the reliefs? The chamfer would be done similar to the drawing of the Corvair TRW piston in Panic's 80 book. Other thoughts would be a radius cut on the edge of the piston dome or to turn the area of the piston that is above the relived area smaller so that it would not be scrapped. Or a heavier radius on the edge of the reliefs where they enter the cylinder.
Or am I missing something here?