Re: [AMC-List] Duraspark distributor woes (258 six -- spark plugs)

["Swygert, Francis G MSgt 436 CES/CECM" <Francis.Swygert3@xxxxxxxxxxxx>]

Andrew, remember the comments on the Strokers list about extended tip
plugs? The Renix 4.0L used a standard plug and the later HO models used
an extended tip. The standard plug seemed to work better. I think both
were the same heat range. My thinking is that the extended tip gets
physically hotter since it's down in the combustion chamber further than
a normal tip and contributes to detonation (pinging). The standard tip
is more shielded and therefore doesn't get so hot that it causes
pinging. Just my ideas on the subject...  

I agree, the heat range should be the same (a 12 is a 12...), but that's
the heat range the plug is designed to run at under the conditions it
was designed for. In Tom's case it would make a difference if the tip is
further in the chamber than it was designed to be. For the stroked 4.0L
it's just a matter of the more shielded tip working better in the new
environment (raised compression, different piston dish or quench
height).

------------------------------------

" > the L shouldn't matter.  12 is the heat range, and if it's a 12 it
" > should be a 12.
"
" Well the Champion data that Edelbrock parrots says it's .060"
" extended tip; why that doesn't simply translate to a higher
" heat range I don't know.

if it does translate to a higher heat range why isn't it -marked- with
a higher heat range?

my argument is that they compensate the design for the extended tip so
that a 12 remains a 12.  anything else would make a hash of the
marking system.

" > " So I've mailordered RC9YC's, and will play with timing with
" > " these colder plugs when those arrive.
" >
" > this should be the significant change.

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