Join Date: Mar 2003
Location: Williamstown, WV
The AR's have a "coating" and the ground strap only extends half way across the electrode giving the "spark" a cleaner path into the combustion mixture. I've been running the 3924's and I just installed a set of AR3923's to see if I can gain anything from it. You want to run as "cold" a plug as you can get away with without cold fouling. My 3924's didn't look bad but had a slight brown glazed look on the tip of the porcelain, so I dropped one heat range. Colder plugs reduce the chance of detonation as well. Check out the autolite website, they have good info and pictures.
Champion plugs are NOT the brand to use in your ford. Some may say it doesn't matter, but it sure did in the 69 351W 12.5:1 motor I had in my 91 notch last year. I had been running motorcraft plugs in it, and when I went to get a new set, the parts store had stopped carrying them. They cross referenced to a champion plug, so I ignorantly bought the champions. Went to the track, and the car had slowed down significantly. At first I thought it was the heat/humidity, or my carb tuning, but before I jumped into adjusting anything I mentioned I had just changed the plugs to champions. An "oldtimer" "ford to the core" buddy of mine perked up and said their's your problem! I had the old set of motorcraft plugs I had taken out, checked the gap, reinstalled them, next pass (and the rest to follow) the car picked up over 2 tenths. Same heat range.
91 notch, 408W, 10.5 comp, Jay Allen cam, Crane linkbars, Scorpion rockers, vic jr intake/heads, Canton pan, Mac longtubes, C4, UPR adj. uppers/lowers, Strange struts/shocks, subframe connectors, wild rides 6pt, Team Z k-member/anti-roll bar, MSD ignition.
Last edited by Mattstang65; 08-03-2008 at 08:35 PM.