Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!
The Gen3 uses motorcraft sp551 or sp558 while the Gen 2 uses sp548. The are identical as far as thread, reach and gap but the Gen3 has a heat range of 7 vs the Gen2 heat range of 6. Found on O'Reilly's web site.
I'd give Shaun a shout since he is doing your tuning. Your plug heat range may depend on where he maps the a/f mixture and timing advance. It's all going to depend on a happy medium of getting the best burn and least probability of pre-ignition.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.