Guys, just got an 80 camaro to be used as a bracket car. on the test drive it started fouling plugs. owner thinks it is b/c the plugs are too cold since the motor is built to run nitrous. said he had been driving it previously (about 300 miles) on the street without much problems. The plugs are Autolite 134, AR134 I think. I do NOT intend to run nitrous at all, might put the car on the street if I can get it inspected by a "friend" (that's the only way it will pass). Anyway, what plug do y'all recommend I run? thought maybe i'd go one range hotter which i think is a 135. here is about all i know about the motor:

400 small block 4 bolt mains destroked to a 377 (bored .030 w/350 crank)
Compression ratio is about 11.5:1 (I not 100% sure on that)
I think the guy said he runs about half high octane race gas and half 93 premium
220 motown heads
Comp Cams hydraulic cam
Forged pistons
Forged rods
Hedman full length headers
3" exhaust with mufflers (it is LOUD though)
Holly 750
MSD 6AL Ignition
MSD Pro billet distributor
MSD timing control
MSD wires
**I Don't know what the timing is set to currently
**I don't know how decent the carb tuning job is right now, will get that checked out by a friend

the guy had been spraying a sniper 150 shot (dry I think). only has about 10 passes with nitrous on it. motor is pretty freshly built.

In the 1/8th, car ran 7.90s all motor, 7.10s-7.20s nitrous, with Slicks and 3.73 gears, full weight. So you can get an idea of the power range there. maybe 400 -430 crank HP on motor?

thanks for any help with the plugs. i'm not adverse to changing brands, looking for recommended heat ranges and specific model #s if possible. thanks!

 

Your spark plug heat range is not the problem, if anything I would go one number colder. Replace the bushing in your distributor to the biggest one, I don't remember the color, this will limit centrifugal advance. Reset the ignition advance to 36 - 38 degrees total.

 

Autolite 3924 or an NGK FR4 or FR5 sounds about right as far as trying something hot and new. Those are all projected tip, .75" reach gasketed plugs.

I have been running my carburated 396 stroker at 36 or 38 degrees locked(no advance) with no issues other than clean plugs. I'm not sure if I need 32-34-36-38-40 but a day of track testing will tell sooner or later. Goodluck!

7.90's is equal to low 12's in the 1/4 mile. A 3500lb car could be making 375-425hp to do that with normal gearing, traction, etc. I think you need a good track day for tuning and sorting things out. The engine sounds like a stout combo with 400 cubes, 11.5:1, Motown 220 heads, hopefully a somewhat aggressive camshaft, longtunes, etc...Camshaft plays a big part in power but that thing should be able to make 500hp on pump gas and be pretty driveable with those cubes and heads... What trans, gearing, converter, carb, intake?, etc?

 

think i found it. damn distributor was loose, go figure. it was turning freely back and forth by hand. thanks.