Last fall I blew 5 out of the six head gaskets due to detonation. Rebuilt the top end and was running it in the shop last week when it suddenly locked up. Engine would not move either way. Pulled it out AGAIN and found two rods had spun the rod bearings. Numbers 3 and 4. I had gone to great lengths to insure I would always have oil to the rods. I had cross drilled the crank, grooved all of the main bearings and installed a 993 oil pump. It had good oil pressure when I was running it, ie 25 psi at idle.
I was wondering if this failure didn't start last fall when I detonated this 12.5:1 compression engine. Here are some pictures of the bearings,
