What gap would be right for a 396 with HEI? I gapped the plugs at 35 when I put them in a few months ago. A couple have been fouling pretty easy, so I got a new set today. A light went off and I relized 35 was for points ignition, HEI in the new stuff requires a gap of 60, I think. Should I go with 60 on this set of plugs? As always thanks for the help.

I usually gap mine at 43 to 44. Been fine for me.

.035 to .045 here

I use .040. When HEI's first came out they set gaps at .060. This was found to be too much and GM quickly changed to .045.
Bill

.035 for the points set up, .045 for hei set up, you say that couple of the plus been fouling are you letting the engine idle alot? i think the highest you would go to would be .050 and the engine doe's like that to well. bill:thumbsup:

On our L78 I run .035" gap. It will grow with age. Too much gap and the spark will find another route if there is one available. Path of least resistance. Run your engine after dark and check it out. You might be surprised by the light show if things aren't perfect.

.035 with MSD 6a. Try a hotter plug

Have only ran the motor 40-50 minutes since new cam install. Mostly 2000 and up. Started backfiring out the exhaust yesterday when I ran around the block. I put in new Autolites today, gapped at 40. Not right on moderate/heavy acceleration. Feels like choke, fuel problem. I need to take off the aircleaner to make sure the choke is pulling all the way off. I was worried about cam when it started backfiring, but it didn't do that with the new plugs, only stumbled on accel. Sure it is just a tune up issue and won't be hard to diagnose. Old plugs were 35, new ones 40. Is that enough change for some fire to go to ground? Doesn't that usually happen only at idle? All I know is points, this is the first hei I have run.