Wishmaster's87IROC

iTrader: (4)

what plug you guys running with your AFR heads? also what should I gap them too?

thanks..

actualy the plugs I have are autolites 3924's will those be ok?
they have the 3/4in long thread length.
they were cheap and thats what Im going to use for initial start-up when I get this motor running.

rgarcia63

That's fine for settin up, use a .035 gap.
My heads are GMPP alum fastburns which uses the same type of plug.
I use an NGK FR4 @ .035 which I will open to no more than 1° (.045) after I done tuning.

I noticed you show a power adder, leave them at .035.

Correction: The NGK is a TR5

Wishmaster's87IROC

iTrader: (4)

ok..cool so gap them to .035...and I will have the Nitrous hooked up but wont run it for awhile....oh and another question.

my autolites came with this like little metal washer type thing ...use those,right?
when I had the old motor my old plugs didnt have that thing...Im thinking they are to press fit into the head and make for a good seal..or something..

rgarcia63

They are compression rings, these are not stock 3rdgen SBC 305/350 tapered seat spark plugs with 14mm threads @ .46" reach which is an Autolite 146.

The plug I see recommended for the AFRs is the AC FR3LS with 14mm threads @ .75" reach and compression rings, which is an Autolite 3924 which I can't use on my heads because fastburn uses tapered seat plugs like the stock head and a slightly shorter reach (.708.)

Damon

The 3924s are built for a .040-.045 gap. If you gap them down to .035 the center electrode will be bent in at an angle. Those are the plugs recommended by AFR so, yes, they'll work.

Wishmaster's87IROC

iTrader: (4)

..you guys are confusing the crap outta me with all the numbers and tapered seat stuff.

will the auto's work and if so what gap? I can always take them back.

do I use the compression rings?

Dialed_In

iTrader: (3)

Plug gap and heat range is going to be detirmined by how the entire motor is setup, not just what heads are on it. I use NGK plugs in my bracket car that has AFR heads, they work good and I always have them in stock. NGK 5671A-8, the 8 being the heat range of the plug. It is a washer seat plug with compression ring. Once it's broken in you'll want to change the plugs. Run it for a little bit with the new set and read them to detirmine what heat range the motor wants. You'll look at the threads and you want to see 2-2.5 threads discolored from the heat. If it's less than that the plugs are too cold. If it's more the plug is too hot.


BTW with NGK plugs, the lower the number the hotter the plug. A -7 would be hotter than a -8. It's the opposite of Autolite.

Wishmaster's87IROC

iTrader: (4)

K..I'll use the Autolite 3924's and gap them at .045 and just use them for break-in and then after that I'll get some good plugs..that I can use with my Nitrous..

rgarcia63

Yes, use them no problem.
As for the confusion, you actually brought it up with:
= tapered seat.

Press fit no, seal yes.

As for the numbering, I apologies.

I do insist that there is no problem with gapping a plug +/- 1° (.010") from horizonal, so you can gap an .035 plug to .045, or .025 and an .045 plug to .055, or .035, but there are manufacturers who insist that their gap should not be changed, so for warranty issues I would side with them.