Spark Plug Preference
Thread Starter
Burning Brakes
Joined: Feb 2000
Posts: 852
Likes: 112
From: Torrance California
Spark Plug Preference
Getting ready to change plugs in the 67 427/390. I believe the manual calls for AC R43XLS. I think I remember some of the forum members are using the R45XLS. Is the only difference in the heat range? Which one is prefered? I've been using Splitfires for the past few years and they run ok but are harder to find now and just rather use the AC's.
Desert Nomad,
Desert Nomad,
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Getting ready to change plugs in the 67 427/390. I believe the manual calls for AC R43XLS. I think I remember some of the forum members are using the R45XLS. Is the only difference in the heat range? Which one is prefered? I've been using Splitfires for the past few years and they run ok but are harder to find now and just rather use the AC's.
Desert Nomad,
Desert Nomad,
Le Mans Master
Joined: Jun 2004
Posts: 9,015
Likes: 331
From: Southeast Missouri
Getting ready to change plugs in the 67 427/390. I believe the manual calls for AC R43XLS. I think I remember some of the forum members are using the R45XLS. Is the only difference in the heat range? Which one is prefered? I've been using Splitfires for the past few years and they run ok but are harder to find now and just rather use the AC's.
Desert Nomad,
Desert Nomad,
The only difference should be the heat range, I run the 45's and they work well. A little hotter plug than the 44's, but I haven't had any issues with the plugs overheating. A lot of my driving is local and without the engine having a chance to come up to full operating temperature and the 43's are just too cold for this type of driving with my engine. Go with the 45's . . . . .
CF Community Team
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From: Cape Cod, Mass.
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R45 XLS is what I run in my 427/390. I like the 5 heat range in street driven big blocks as well as small blocks.
Melting Slicks
Joined: Jan 2002
Posts: 2,132
Likes: 71
From: SOUTH SHORE Massachusetts
I agree with you Paul, I use the 45's too...and put lots of miles on them without any problems, current set in now has about 15000 miles on them. The car will be getting new ones soon...for the trip to Carlisle.
Thread Starter
Burning Brakes
Joined: Feb 2000
Posts: 852
Likes: 112
From: Torrance California
My car came with Splitfires and they ran well for over 10 years. Nothing against them but seem harder to find latley. I'm going with the 45's as stated above. They'll probably last longer than me.
