The internal resistance is supposed to reduce the electrical energy radiated
from the plug/plug wires at radio frequencies. Without it you might hear a
pop in the radio each time a plug fired. As to why there is a difference in
resistance between the plugs, I can't say. Spark-plug wires for automobiles
is often made of resistive material, for the same reason.
Jim
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James E. Kearman
jkearman@javanet.com
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This is a good subject. Today I picked up a box of Champion and a box of
NGK spark plugs. Not so long ago I had a bad Champion straight out of the
box. I mean, an infinite resistance from the top of the plug to the center
electrode. So I now make a point of checking them with the multimeter.
Anyway, if I'm reading the multimeter correctly, the Champions were
between 50 and 100K ohms. The NGK plugs were between 2.5 and 3K ohms.
What's the deal?
Old farts want to know.
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