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Discussion Starter #1
I replaced the plugs recently and went out for a drive. When I rode it hard just for a little while, I developed a bad miss. I went to do a compression test and three of the plugs had the gap completely closed, 2, 6 and 7, not that it matters.

What would cause that to happen (and no I didn't drop any and was very careful installing them)? Piston cantacting them? Something rolling around in there?

They are 3924's and I have twisted wedge heads.
 

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On aircraft engines that is called a shorted secondary, usually caused by detonation, what is your timing? what kind of fuel? Could the mixture be lean? I would get it on a dyno soon, you may already have piston damage.
 

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I'd definitely say it was caused by detonation. I've seen that before on blown engines especially. Actually one time me and a buddy were racing a firebird on the interstate and had that happen. Pulled over at a gas station and started pulling plugs until we found it. Actually broke the porcelain around the center electrode. He ended up blowing the top of a piston into the oil pan with the skirt still on the rod......
 

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Discussion Starter #6
I've seen melted plugs while running nitrous before and this wasn't the case here. They were physically closed as if you had dropped them.

I had the washers in place so that wasn't the problem. I'll try doubling the washers and see if that helps.
 
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