This may come under the heading of picking the fly specks out of the pepper,
especially with our cast iron lumps, but I've understood that "indexing"
plugs with reusable solid copper washers can make a measurable difference on
the dyno with certain engines. Apparently some combustion chamber/plug
angle configurations are more responsive than others to having the side
electrodes aligned in an optimal (and consistent) manner with respect to the
chamber. The approach I'm familiar with involves marking the electrode
location on the outside of the plug and adjusting its seated location with
the use of copper washers that are lapped to the required thickness.
Ideally, this starts with the determination of what the head prefers
regarding electrode location and extent of plug projection, and this is
factored into the initial preparation and cc'ing of the head. Once you are
there, you do not replace these non-crush type washers with any regularity.
It's probably worth mentioning that my experience with this is with alloy
heads using anti-seize on the plug threads and very low torque. Worst case,
this is a low cost obsessive-compulsive exercise that can help to while away
those long periods between on-track sessions.
Dave Talbott
----- Original Message -----
From: "Don Marshall" <marshall@nefcom.net>
To: "FOT" <FOT@autox.team.net>
Sent: Wednesday, April 09, 2003 4:51 PM
Subject: Spark plug washers/gaskets
> Has anyone got a source for spark plug washers/gaskets? I was taught to
> replace them every time I clean the plugs but I can't find them locally
> except with
> new plugs. As cheap as plugs are, I don't want to put new ones in
everytime
> I want to check the mixture, etc. Thanks, Don
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