Thought I would get this thread up to date. Motor was finally taken apart last week. Bearings were not terrible but did show signs of the detonation, they are being replaced however since it is at this stage. Couple of other things were learned upon disassembly. Instead of the block supposedly being bored .010 as per his sheet, it was actually bored .020". Also the pistons were .030" down in the hole instead of the .010" that he wrote down on the spec sheet. With these measurements, he is coming up at 10.1:1 compression. Brian has no idea how these measurements were not recorded correctly. I believe they had 2 of the same type builds going on at the same time and measurements were not following the correct build. He still has no idea why this motor was detonating because he has put together quite a few the exact same as this one with the exception of the intake manifold. We used the short Weiand Action + for Ramcharger ductwork clearance. He doesn't think that is the issue, but who knows.
So Monday he is ordering CP full dish 30cc pistons with some swirly cuts and will use a .040 or so head gasket to get a compression ratio of 9.7:1. Also is ordering a different cam to drop the cranking compression down to 170ish. So what is everybody thoughts on this plan?
One other question. He said he will be able to order the new pistons the same weight as the old ones, so won't have to rebalance. Is that common practice and wise to do?