spark plugs too hot - WR5? Autolite 45s?

colt65 · May 20, 2004

I think I'm running too hot a plug right now, seem to be getting some detonation at high RPMs under load, which isn't good. I'm running a set of NGK WR5IX Iridiums, and I think those are too hot. I used to run the NGK WR5's without a problem -- anyone else running a high compression SB with a MSD 6x? I think I may need to go a few steps cooler than the Autolite 45 or WR5, but I don't know what the numbers would be. Ideas?

Robdogg67 · May 20, 2004

I used to run a Motorcraft BF-42 (I think is the same as the Autolite 45 now)in my old 289 HP, too hot for me. Then I switched to the colder Autolite or motorcraft bf-32 and it made a significant improvement in performance. They are hard to get nowdays only through NOS places. You might also try whatever the next modern colder Autolite model is, maybe a 44? Good luck!

jikelly · May 21, 2004

I have never experimented with plug temperature before. That might have help me keep my last motor from dying on me. The one I have now has a pretty low compresion ratio and I haven't had any problems with detonation thus far.

spark plugs too hot - WR5? Autolite 45s?

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spark plugs too hot - WR5? Autolite 45s?

colt65

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