[bobcowan]

It all depends on what heads you have. Look in the book for the heads, and see what plugs they recommend. Then cross reference for the Autolite plugs.

I'd probably start with a 0.035" gap and adjust from there.

I have Dart Pro-1 heads. i use a Autolite 3924 plug, gapped to 0.035". That seems to work well.