Rick Jennings wrote:
>
> What determines if a plug is "Hotter" or "Colder" then the standard plug?
I'm not sure what kind of answer you want. Somewhere in the ID of a
spark plug is a number. The same ID with a larger number is 'hotter'.
Lower numbers are 'colder'. Thats one answer.
The center electrode of a spark plug is cooled by transferring heat to
the ceramic insallator and then to the metal body and, finally, to the
cylinder head. The ceramic insallators have different shapes within the
plug body. Some are 'pointy-er' than others. The pointy ones are hotter
as the ceramic insallator does not contact the plug body until deeper
into the plug. Cooler plugs are just the opposite: these ceramic
insalators are blunt and the distance from the electrode to the spark
plug body is much shorter.
Bob Allen, Kansas City, '69CGT, '75TR6
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