Paul,
IMHO, (my opinion), this just isn't true. I suppose if I built exhaust
systems this might explain white plugs, (no joke intended). Actually,
any color on a plug, (short of some strange additives that turn them
pink or other odd colors), is a result of mixture remaining on the
insulator that wasn't burnt off. Lots of times you may have a white
plug with specs on the insulator and in this case the specs aren't
mixture residue but little pieces of aluminum from the top of the
piston. Of course it should be noted that plug color changes rapidly
and reflects what was happening just before the engine was shut down
... Most of the time when we just roll in the garage and pull a plug
we are really seeing our pilot mixture .. ). In addition to the
"color" that might appear on the plug it often appears only in certain
areas for a variety of reasons, (the old half tan half white syndrome
.. where the part of the insulator facing away from the intake valve
is the demark).
Generally, the "color" or "ring" will work it's way from the metal
plug shell .. down the valley to the insulator and up the insulator to
the tip depending on how hot the insulator actually gets. Obviously,
too hot a plug or too lean a mixture will never show on the insulator
but you can usually follow the metal shell up and see a line
somewhere. I remember mixing VP Red .. a very pure 108 octane racing
fuel with regular street gas ... this stuff always made the plug
insulators and the exhaust pipes a very light tan ...... still you
could find a line if you looked carefully somewhere on the metal shell
or the body of the insulator. In this regard I might buy that really
pure fuel with no additives would be very hard to read but lead
certainly is not a requirement. Of course .. sooting and fluffy carbon
buildup from an excessively rich mixture is always easy to see. IMHO
as always ........
campbell
----- Original Message -----
From: "Paul Kleindienst" <[EMAIL PROTECTED]>
Subject: Plug Reading...
> I was told by someone whose opinion I hold in high regard,
> that you can only read plugs if "leaded" gas in run. This guy
> builds custom exhaust systems (which should tip most of you
> off) and really sounds like he knows what he's talking about.
> Any comments?
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