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Serious southern boy living in Jax Fl.
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It's not so much the spark system more the fuel supply. Electronic fuel injection keeps a plug cleaner longer and when you use high end plugs they stay cleaner longer. Interestingly from what I've read the copper plugs produce slightly more power. I have no idea why.
 

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In a real high performance application, such as over 500 hp Small block/600 hp big block naturally aspirated, or any power adder above those power levels.....those thin wire electrode exotic metal plugs become a detriment.

Reason is the smaller wire cannot conduct heat out of itself as fast, the center electrode or the ground strap overheats during the intense instant heat of WOT, turns into a glow plug, and melts and burns away.

The fatter core wire in the copper core plug transfers the heat out of the electrodes to the plug body easier, so the plugs maintain a workable heat level and stay intact.

You won't find racers using exotic metal plugs unless they can get versions with the same fat wire electrode sizes as the common basic stock plugs would have.

The only real place the exotic metals really help is plug life in daily drivers, that is their prime place to be used.

Within the context of Riverboatman's posted 425-ish HP build, the Iridium plug would be a workable option.....but I would do standard metals plugs in the initial break-in and the first few hundred miles, so if there is a timing or carb tuning discrepancy you have a little more leeway and you aren't gas or oil fouling expensive plugs just to toss them out.
Then change to the Iridium for long life after you've got the tune figured out.
 

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2,006 Posts
In a real high performance application, such as over 500 hp Small block/600 hp big block naturally aspirated, or any power adder above those power levels.....those thin wire electrode exotic metal plugs become a detriment.

Reason is the smaller wire cannot conduct heat out of itself as fast, the center electrode or the ground strap overheats during the intense instant heat of WOT, turns into a glow plug, and melts and burns away.

The fatter core wire in the copper core plug transfers the heat out of the electrodes to the plug body easier, so the plugs maintain a workable heat level and stay intact.

You won't find racers using exotic metal plugs unless they can get versions with the same fat wire electrode sizes as the common basic stock plugs would have.

The only real place the exotic metals really help is plug life in daily drivers, that is their prime place to be used.

Within the context of Riverboatman's posted 425-ish HP build, the Iridium plug would be a workable option.....but I would do standard metals plugs in the initial break-in and the first few hundred miles, so if there is a timing or carb tuning discrepancy you have a little more leeway and you aren't gas or oil fouling expensive plugs just to toss them out.
Then change to the Iridium for long life after you've got the tune figured out.
Thanks, Eric! Good advice and that makes good sense!
 

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1965 2door HT Helena, GA 31037
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Discussion Starter · #24 ·
Eric, what you have described sounds like the way that I am going with this engine. I really appreciate all the
info you guys have been giving me. I rely on you guys a lot for info and you always help me. NPHNP!
Sam
 
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