1fas92

I am trying to find out what would be the best plug to run on my car.
Here is a little information:
1992 Z28
supercharged 383, 210 afr heads, tpis mini ram, long tubes with dual exhaust & fast ecm. I have autolite's in it now (not sure which one, without looking)

I want to know what to use at the track & use on the street. Becuase on the street to use a different plug vs the track.

Thanks,
Robbie
1fas92

NC-LT1

I am starting out with autolite 104's, they are a range colder then what the factory spec autolite crossover would be.. we'll see how she does on them!

you can also try some TR6's from NGK, I choose autolite for ease of attaining them, any advance or autozone carries them and swapping them out is less then $12 bucks.

Chris

1fas92

What would you gap that plug? I am gapping mine now @ .35 with the autolite's that iam running now.

Thanks,
Robbie

hulettsz28

NGK TR6. gapped at .35

Cmr0z28

With AFR heads?

97WS6Pilot

I ditched my autolite 104's. They were too cold for everyday driving and a couple fouled. I just put in autolite 106's which is one heat ranges hotter. They are the plug recommended for stock motors. So far I'm not getting any knock at high rpm and high boost.

lethal93ta

I was running the stock temp plugs in mine to just ran a smaller .035 gap, I had a major booging problem with a colder TR6 plug in mine , Icould only get 2.1 60 foot times booging, with the TR5 I get 1.9 60 foot times. I swaped them back and forth a couple of times and everytime the TR5 would boog out on me.

Sean94Z

Yea, you need a different plug than the stock style with AFR heads.. If you do a search, you can find the right cross-reference.

1fas92

Here is a little info I got off of other turbo sites. The guy that installed my fast system build's turbo Buicks. Well he said to run this plug, so I going to try it this weekend. But thanks for everybodys help on this one!
R5671A-10 NGK V-POWER RACING PLUG 5820


R5671A-7 NGK V-POWER RACING PLUG 4091 Hotter plug
R5671A-8 NGK V-POWER RACING PLUG 4554
R5671A-9 NGK V-POWER RACING PLUG 5238
R5671A-10 NGK V-POWER RACING PLUG 5820
R5671A-11 NGK V-POWER RACING PLUG 6596 Coldest plug

Kevin Blown 95 TA

Why is that Sean? Can you give a little more explanation? I have been using stock style plugs or one heat range colder without any issues, but if there's a reason not to, I'd like more info. I'm not sure what you mean to search on here without wasting a lot of time looking for this plugs/AFR/cross-reference thread.

mzgp5x

I have been running the new Zex plug. They claim it delivers more spark energy and runs cold due to copper core. So far, looks to be OK. They claim it does not fowl due to additional electrodes. We will see. I was running a NGK tr-6. I've been fowling them.
_____
383 d1 15 psi w/ afr 190 heads.

CJ

You cannot run a stock style plug with the AFRs. If you are your probably screwing up your AFR plug holes and not getting a good seal. AFR heads have a flat surface where the spark plug butts up to the head and requires a plug with washers. The plug holes on stock heads have a tapered surface and require a tapered plug.

I seem to have good results with AC delco spark plugs, plus theyre cheap and readily avalible at any parts store.

R42LTS for stock heads
FR1LS for AFR heads.

Sean94Z

Kevin, CJ has it right .. You need to run a gasketed plug in the AFR heads, that's what they are designed for. The stock plugs are tapered to fit into the head and create a seal w/o a gasket. Autolite 103's, 104's etc are like that.

The gasket looks like a washer on the plug and seals up against the heads when you put them in.

I run Autolite 3923's, which are 2 heat ranges colder than stock. Also, the post above shows the NGK R5671-A8, which is also 2 heat ranges colder and is the big turbo guys swear by these plugs.

Good luck on your plug swap, it's such a PITA

Kevin Blown 95 TA

Boy, you're sure right about that !!! - I have them off the engine right now, and they sure enough designed for a gasketed plug. I know the difference - I just always assumed a tapered seat in those, but after 5 years they still look like new, so I'll get the gasketed plugs & I'm good to go. I never had any sign of leaks before, and they were sealing up - OK I never overtightened (I just got done CCing the heads with alcohol) but it couldn't have been optimal fitment. Glad I didn't overtighten them and screw up the sealing surfaces. Thanks for the valuable info!!!

Blownbird355

Keep cheaper plugs like the Autolites so you can afford to change them more often.