ops: had a (Pro?) build me a nhra 396-375hp engine for my Chevelle. After 9 runs it broke on the starting line at dragway 42. I took it apart against his wishes to see what went wrong. One of the inner main bearing bolts fell out and wedged between the crank and block at 5500 rpms. Ouch. It broke the block, ruined the rod and bent the crank. I called him and he told me ( calm voice) that all big block Chevys had that problem and he wasn't the blame. He never once offered to make good on his mistake of not torqueing the main bearing bolt. go figure--- lesson learned-- never let someone work on your motor that doesn't have a reputation of standing behind their work. Shit happens in a race environment but you don't need rookie mistakes compounding the problem. I always wondered what he would have told me happened if i let him take it apart. Don't know-- that was 40 years ago and i still haven't talked to him to find out.