sounded like a header gasket or a lose rocker tightest all header bolt adn check rockers, and the noise still is around. it only makes noise when i am on gas or in drive, when i'm in park or nuetral it doesn't amke the noise adn when i'm at a constant speed it doesn't make the nosie what could it be? a bad torque convertor?

Spark knock-pinging- check timing and try high test gas.

My 2.8L S-10 makes the same noise.Crack in the cast iron exhaust manifold. I can rev all day in park and not hear it , but under load it sounds like a 30-30 cam gone bad.Impresses the ricers though. I'll put headers on it if and when this little guy goes(130000+ miles on this rebuild,260000+ overall).