Deenasty

I need a spark plug reccomendation for a 383 10.4:1 Comp. Its got AFR heads, so I need a gasketed plug. AFR reccomends to start with the AC FR3LS. Should I start out colder? I currently run the NGK BKR5E. The motor runs hot, not the temp gauge, but When I open my hood after a drive, the engine compartment is suppper hot. What do you guys reccomend, and gapped at what? Thanks!

Z28barnett

The spark plugs will have no effect at all on how hot the engine runs.

If that is the problem that you are trying to solve, look in other areas. You could try a new thermostat, waterwetter, check the fan operation and so on.

Heat range on a plug is how hot does the firing tip gets when the engine is running. As long as it gets hot enough to burn off carbon and stays cool enough to avoid melting down, thats as good as it gets.

WS Sick

Its a general rule that the more Horsepower you add to a motor whatever the method, you should go down in heatrange of the plug to stave off detonation. I am using the Autolite 104s in my 383 and they selfclean very well.

Deenasty

z28: I dont mean the coolant is hot or the car is overheating, just the motor is letting out a lot of heat.

Ws: AFR reccomended me the Autolite 3910...its a gasketed plug, because I have the AFR's..

WS Sick

Hmm, My AFRs have a factory style taper.

Deenasty

really, all AFR's are flat taper, requiring a gasketed plug...check them out

www.airflowresearch.com

1racerdude

Extra under hood heat could be caused by a header change and not being coated with ceramic.
More HP will bring more heat,not water heat but heat from heads,exhaust,block,ect.

SS MPSTR

Absolutely correct.

Deenasty

my headers are ceramic coated...

5.7LT1Formula

i just fired up my 383 with bosh platnium plus 4's..expensive..but i like them..also have a friend running them in his highly modd. engine and runs just as good.

WS Sick

Says there they used the gasketed plugs, hmm. I wonder. I looked my heads over good and they have a tapered seat, the plugs seal good as well. I wonder if my machinist did something. Or maybe I've just been using the wrong plugs....lol

WS Sick

In the 3910 Autolites is that equal to the factory heat range or is it a step colder? I might see if they fit better and use those instead. I want 1 heat range colder than stock and autolites site is no help...lol