On Tue, 20 Nov 2001, Sally or Dick Taylor wrote:
> Eric---I wonder why it is, that the late model head with its lower
> compression would call for the colder (N9) plug?
I'll take a guess and suggest that this is related to the retarded timing
settings for the later cars. I know the 74 had the timing set to 4 ATDC at
idle... and this makes the whole motor run hotter.
> This is the plug that
> caused premature fouling in some of the early seventies engines. Do you
> remember the source that recommends this heat range for the 75-76?
Ummm... the owner's manual?
> Also, a "shorter" plug could expose the sharp corner in the head near
> the tip of each plug, creating a hot spot.
The shortness here is just the length of the tip, not the overall length
of the plug. All the N type Champions have 14mm threaded section that is
.750 inches long.
> Dick T.
> '73
regards,
rml
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