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Author Topic:   Detenation troubles?
Dirt Forum Champ
Total posts: 796
posted August 01, 2005 12:22 PM  
I got some detenation on the #2 cylinder. Spark plug had small specs of aluminum ( i believe, thats what it looked like) on the plug end. The plugs end gap was closed to about .010 gap, looks like the tip got hot and when it cooled back down pulled together. At least i think so.

Motor got hot once, about 230*. We corrected it, has been running cool since, no higher than 190*. We found this a week later, the car had a stumble / miss on power. So we pulled the plugs and found the one bad one.

Anyway, we cleaned it re-gapped it and put it back in and the car ran fine with alot more power, no stumble or miss. We believe its not hurt bad, maybe some slight detonation but not bad enough to really hurt the engine, i hope.

Anyway we pulled it out, what should i look for that would cause this? I believe it happened when it got hot the one time, but wanna make sure there isnt something else that could cause this.

Should the pistons be replaced if its been detontated on? or the valves? Any other thoughts?

Also this is an alcohol motor, 365 cubes with Dart Pro 1 cylcinder heads and Ross domed pistons.

Thanks, Krom.

Dirt Maniac

Total posts: 116
posted August 01, 2005 04:26 PM  
Do a compression, or preferably a leak-down test. See how that cylinder measures up against the rest. It probably didnt hurt you though...

To give yourself some more lee-way you could pull 1-2* out of the timing, or you could go up one size jet, or down one heat range in spark plug. Doing any one of these should give you a buffer. Or you could just make sure it stays cool. Anyway, good luck.

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