How would someone go about determining detonation? If i was to go to 93 octane from 87 would it stop pre-ignition? How would i fix it if i was having this problem? Car makes a sound almost like a jackhammer when held at a specific rpm. Then goes away when throttle is let off or opened up more
Possible detonation??
- Thread starter 79cutlasssalon442
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Noisies are sometimes hard to relate, but detonation will make a gas engine clatter like a disel. Usually will get worse or start uder a load like accelerating up hill. If it is detonating to much timeing (distributor advanced), a lean condition BIG vaccum leak or to small of jet in carb, or not enough octane on a higher compression engine. If you have a timing light i would check advanced first. (remove vaccun line from distributor plug hole on carb side and bring rpms up to about 3000, shine timing light at balancer) If its runing lean check spark plug rich is black, good is tan or brownish, lean is a white or light grey, but plug needs to be checked after power run. if your running 10 to 1 compression or a little to much timing higher octane should help
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