Extender leakage?

If they were installed clean, then come out looking like that, yeah. Carbon Arc tracing. The spark will jump thru the extender housing to the cylinder head, burning holes on the way. But they tend to track and trace along the way.

 

One of mine looked like this.
Alden
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I removed mine long ago for these reasons. Connect the wires directly to the plugs.

 

If they are doing that, presumably the actual internal contact to the plug must be poor.

 

How does it look? Pics? Are you still using the round black rubber boots?

 

Yes, boots still in place. Image Unavailable, Please Login

 

QV with wires run through the stock boots straight to the plugs
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Same on my "TR V12"
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Edit: I 've never tried with the stock ignition system, I used aftermarket coils on both setups. It should work with stock stuff, but I've not done it.

 

If there is going to be leakage of the electrical sort it's not going to be to the ceramic insulation around the plug so my vote is - NO