Re: Spark Plug Heat Range

[<trinitygadget@alltel.net>]

With performance increases, you want a plug that will dissipate the greater 
amount of heat of combustion faster, i.e., a colder plug. My engine is warmed 
over with a 9.5:1 CR and an Isky cam, so I installed RN9YC Champions.  I doubt 
BL had this in mind when they recommended the 12Y for pre-73 TR's as the 72 had 
a fairly anemic CR of 7.75:1.  Perhaps as others have suggested it was chosen 
for emissions purposes.  I recommend RN9YC (or other brand equivalent) for your 
application.

Rick O.
72 TR6