Hi John,
Copper is a better electrical conductor than Iridium (and Silver is the best
of all). This is a relative ranking and these differences in conductivity
do not make any difference in this application - ie they are all "very"
conductive.
Iridium is useful because it does not readily form oxides even under extreme
heat conditions. So in your cylinder head with all of the combustion
products and the heat of the spark, the Iridium is is going to be relatively
inert. I think the cautuion about adjusting the gap is because Iridium is
also brittle.
Are these plugs worth the money? Is this just marketing hype? I don't know
enough to say. I don't think I will be the first kid on the block to buy a
set though. Let me know how you make out.
Regards,
John Cyg.
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