So I am at that stage to almost start my new 383 and I have spark plug questions? I bought some Champion spark plugs and they do not fit due to my header clearance. The original paperwork for the heads call for Autolite AR3933 plugs, I did a search for these in all the forums and nothing came up. I need some shorty plugs on Accels website but I am not sure which heat range I need. Does somebody have a cross reference sheet or something?

Thanks, Erik

Not saying these are the best or right choice for your application, but my new Protoplines said to use V57C champions and I could order but not find "on the shelf" anywhere so I had the speed shop cross referance them and he had AR132 autolites. They are the "race plug" with a cut back electrode and are 1/4" or so shorter than a standard plug. Also the accel "header" plugs are alot shorter too but I had problems getting the right heat range in my old "stocker" heads. I hope this helps some.

i've been running ngk V-power racing plugs in my 406 w/ protopline heads for 3+ years now, they work awesome, and they are pretty darn short, close to the "header" plugs from accel. i dont have the number handy right now, but any parts guy that can look things up can find them, just ask for ngk V-power racing plugs, (washer seat obviously) in a 7 heat range. 7 is what i use, and is the hottest these plugs come. just as a comparison, the 7 second nova we race runs the same plugs in a 10, with about 600 horse of nitrous. 7's should be good, i've used 7's and 8's in my 406.
i can get the # tommorow, its just out in the garage right now.