I built an L28 with standard flat tops,a P79 head shaved .080 shimmed cam towers and a Stage III Isky reground cam. Everything in the engine is new (rockers, springs, mains, inserts, chain, oil pump, guides, crank pulley,cam pulley, etc. etc. etc.) The engine runs great! However, when you rev the engine to 4,000 and let off, it makes a ball bearing type of noise at 2,200 rpm on the letdown.When you run it up the noise comes on at 2,200 and disappears at 3,000 rpm. I've eliminated the oil pump, t