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
porcelain,
instead of being curved like sine waves, had flat sides and bottoms. Didn't
think
much of it till I came to remove them some time later to check the gap, and
broke
three of the buggers. Before that I had only broken one in 30 years. Last
time I
use them.
The spark-gap thing reminded me of a gadget that was available in the 60's
called a
Scrutton something or other. It consisted of a stack of washers each insulated
from
the next, and each with two grooves cut across the diameter at right-angles to
each
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
extra
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
wouldn't
start. I would pull the king lead out of the coil such that the metallic
contact
was broken but the lead was still held loosely in place by the rubber cap. As
I
recall it usually fired up right away whereupon I pushed the king lead home
again
and went on my merry way.
PaulH.
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