Thread: Engine knock
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06-23-2005 04:59 PM #1
Engine knock
Well this isn't good. We have developed a knock in a 383 stroker. It sounds like piston slap. It only happens at very low idle or under load (stopped and in gear- it's an automatic). We did a hot compression test and found that #7 is running about 25 pounds higher than the rest. Most are running about 170, #7 is running at 200. We just ran it and started disconnecting plug wires one at a time to see if we could get the knock to stop. When we disconnected #7, it stopped knocking.
So the question is - why is #7 compression so high? Or why are the rest so low?
Welcome to CHR. I think that you need to hook up your vacuum advance. At part throttle when cruising you have less air and fuel in each cylinder, and the air-fuel mixture is not as densely packed...
MSD 8360 distributor vacuum advance