[AMC-List] SPARK PLUG Heat Range info.

["John Elle" <johnelle@xxxxxxxxx>]

For Information!
 
SNIP
the L shouldn't matter.  12 is the heat range, and if it's a 12 it
should be a 12.
SNIP
 



Actually the L does matter. 
With in a given plug style as indicated by the plug coding using 
Champions for a reference as that is the plug line I have data on
such as N-14-Y which is an extended tip plug or N-12-Y which is a 
colder version of the same plug the number is a relative indicator
of the tip temperature. 
 
Change the style of the plug such as N-12 which is a flat tip plug 
the physical tip temperature is different. There for the 12 becomes 
a new relative indicator for that line of plugs and it is colder than 
an N-14.
 
In those two examples tip temperature of an N-12-Y (an extended tip 
Plug is about the same as a N-9  which is a flat tip plug. 
 
Add the other alpha-numeric to indicate copper, platinum or what ever 
The buzz words are you have the same difference extended out to what
ever technology is being pushed. 
 
For example platinum plugs are designed to last longer so are used 
by the factory to be installed in an engine that has lousy plug 
accessibility. You can leave them in longer before the corrode. 
Such as the plug behind the alternator in back of the 3.8 V6 in my 
T & C. I defy anyone to change that plug under an hour and a half.
 
Split fire equivalents with multiple paths can be used by the factory 
to last longer for the same reasons. Spark only goes to the closest 
electrode so as long as the center electrode does not corrode it will 
last longer too. One model Porsche uses this technology as plugs are 
next to impossible to change. 
 
Personally I have found absolutely no change in operation of an engine 
using split fire plugs at all. 
 
I also run about 3 heat ranges colder in all of my engines. ( At least
those plugs that I have data on anyway which for the most part is the 
older plug applications) Plug life has tripled in some cases. Remember 
OEM plug recommendation is a compromise based upon the stereo typical 
usage some one deems the car will be used for. Change the usage criteria
and modify the engine the "CORRECT" Spark Plug could become a whole 
different animal.  
 
For what it is worth 
John.
 
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