Originally Posted by 1bille1
I'm sorry that's incorrect.
Silver has the higest conductance, lowest resistance, and highest thermal conductivity of any metal.
Melting points for copper/silver are aprox. 1900F and 1700 F, respectively. Since EGT's run several hundred degrees F below that, and actual sparkplug temps well below EGT - worries about it wearing away are pretty groundless.
Not to get into a pissing match, if you know anything about electronics, to ensure the best connection and conductivity you plate things in gold. But I am guessing you are a mechanic (or some one that turns wrenches or sells parts) not an electronic engineer.