Well, I'm new to this site, but I've tried everything that I can think of to fix my prob short of yanking the heads off my motor and starting over. I've got a 71 chev pickup with a 78 chev rebuilt 4 bolt with smog heads. The guy I bought the truck from bought the long block and slapped it in about 1 year age. My problem is the thing detonates like crazy and sounds like a glass jar full of marbles. It doesn't seem too though when you put your foot all the way in it. Only at part throttle and mild acceleration does it occur. It's got an Edelbrock Performer, HEI, headers ,and a Carter AFB carb. Anyone got any ideas?