Originally Posted by STROKEXD
What gave you the crisper response - smaller or larger gaps?
Smaller ones - I think they were .028"; larger were .038" with Mallory Super Mag.
But then using MSD 6A (same car/engine) going from approx. .028" up to .040" gave good results with that ignition.
I think the important part is getting a plug and gap settings that work well with a particular combination.
I have used differing plug gaps on a few types of engines to alter on track performance - drag racing, motorcross bikes and kart engines. All responded to gap changes at different times.
I never saw any increase in power doing this, only changes in engine response. It may be as simple as the wider gap creating a better spark and more engine heat therefore more grunt. I don't know!
I don't think it would matter such a lot in a manual car but with an auto - the better the throttle response the harder you can "hit" the convertor.
Lot of theory in there but it works for me.