Hey guys, THE DUDE has a quick question. I am ready to install the spark plugs in the new AFR heads. AFR recommends Autolite #3932 or Champion #C59C. For some reason, the local auto parts store does not list either of these in their book. :confused:

They list an Autolite #3933, but he was not sure if that would cross-reference with the #3932.

So what type of plugs are you guys running with these heads? The heads are AFR 305 with the CNC chambers. Also, what are you gapping them at? I don't know if this affects it or not, but I am running an MSD 6al and billet distributor.

Thanks for the help guys!

I use Champions that I get from the local Kragen. They have the number 71 on the box (that's what I ask for). I have AFR 315 heads.

edit: They are RC12YC, but the jokers at Kragen won't find them under that number. You have to give them the 71 to find them.

AC delco R43XLS seem to work good, 42 if you want cooler, 44 or 45 for hotter plugs. Last year I had 107 1/4 mile passes and appro 10k street miles on my R43XLS and they were still fine when I replaced them this year. My ET did not change with a fresh replacement. Mine you I have AFR SBC heads, but I believe the SBC and BBC can use the same.

Hi Mark,
RC12YC (71) or RC9YC (344) will work in most applications & are a lot less money. The 9 is a colder plug
They do have a new number system as was stated which I still haven't figured out & you may need to use it but I haven't had a problem with the old numbers so far.
Or have them cross to Autolite or whatever your favorite brand is ;)

The C series are the Champion race plugs.
If you want the race plug try the C59YC, it is the projected tip, the C59Y is the projected fine wire tip
You will need to tell the parts guy to look in the race section of the Champion book for the C series.

I got AFR 335s in a 540 street/strip and I am running NGK R5671 A-8. Gapped about .033 and they seem to be working well. I get them from Murray's Auto Parts. Sometimes they have them in stock or 1 day to get them.

Thanks guys! I really appreciate the input..