We have an 83 chevy 350 motor that was just retrofitted with the 305 HO heads. No over heating problems were apparent before the heads were replaced. The motor has been on an airboat, so the temp has been between 160-180 even under a heavy load. Since the head replacement the 2-middle cylinders have lost all compression on both sides. It was running warmer than normal. It would climb up to 220 pretty quick, but would cool down just as fast at idle. When it was re-assembled, it ran about 6 hours before compression was lost. Timing was set at 33 degrees. The pistons basically flaked off at the edges. 93 octane gas was also used. The plugs were pulled and most were a dark tan to almost black. No water was noticed coming from exhaust or in the oil. If it was running lean somewhere, why did the middle two cylinders on both sides only come apart? Thank you in advance...Kenny
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