Adrian Jones wrote:
> 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.
A while ago I bought a set of Champions and noticed that the ribs in the
instead of being curved like sine waves, had flat sides and bottoms. Didn't
much of it till I came to remove them some time later to check the gap, and
three of the buggers. Before that I had only broken one in 30 years. Last
The spark-gap thing reminded me of a gadget that was available in the 60's
Scrutton something or other. It consisted of a stack of washers each insulated
the next, and each with two grooves cut across the diameter at right-angles to
other on the same face. This construction resulted in many small spark gaps
throughout the device that was said to give rise to a high-frequency spark that
would fire a fouled plug, having been developed for the Navy in WWII. The
gaps probably allowed the coil voltage to reach a higher value before it fired,
something I found useful when my Mini van suffered from fouled plugs and
start. I would pull the king lead out of the coil such that the metallic
was broken but the lead was still held loosely in place by the rubber cap. As
recall it usually fired up right away whereupon I pushed the king lead home
and went on my merry way.