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Re: Installed new parts, car runs like shit -- Spark Plugs

TopNotch@ix.netcom.com wrote:
> First of all Carl, I hope you don't mind but I decided to share our
> conversation with the rest of the list as there are many people that don't
> understand this and I thought the list could benefit. I sold foreign auto
> parts from 1978 until 1988 and glean this knowledge from many product
> training meetings that my employer (BAP/GEON) had at the time.

No, this is great stuff.  The embarrassing thing is I think that somewhere
back in the recesses of my brain, I've learned this lesson before, and
just forgot it...;-).

> First letter (in our case either S or T) indicates plug thread (diameter,
> pitch, depth) and construction. R indicates it is a resistor plug. 5
> indicates the heat range. So in comparing the TR5 to the SR5, we can see
> that they are both the same heat range and they are both resistor plugs.
> The difference is in either (or both) construction or thread. I would guess
> that at least the thread depth is difference.

The SR5 was longer and even after the threads ended there was "more plug"
that stuck farther into the combustion chamber.  The TR5 was shorter and
threaded all the way to the end.