[77 TRASHCAN]

Originally Posted by Formulajones

Yes that's pretty much the general consensus as HP increases you want to tighten the gap.

Some of the big HP stuff running around, especially power adder stuff, will run a very tight .020 gap or there about. One reason is to keep from blowing the spark out, on 1000+ HP stuff. Some of the more popular power adder engine builders have talked about that in detail.

I've always kept mine around .035 even on the 300-400hp stuff whether they have a big whiz bang ignition or not. On the 600-700hp stuff I stick with .035 as well.

I've never found any gain on a dyno or any noticeable difference in drivability by opening the gap just because it had a zapper ignition. In fact Smokey Yunick decades ago showed that it really taxes the coil in doing so and found no other benefit.

So on the MSD stuff here or any other style electronic ignition, I stick with .035 and find no need to change it, at least up to the 750 HP level.

X2!!!
My engine builder (of course he is a Chevy guy) always used small gap plugs, gapped at .035, in ANY engine, he also liked the non projected tip plugs, when available per application. He liked to keep that small piece of nearly always, molten petal away from the piston top, just a little bit more...