Is this like that E.F. Hutton commercial?
(MY Ignition geek is TeamRush, and TeamRush says.... )
If you enlarge the cap, you spread the terminals farther apart, so there is less chance of cross firing to the wrong terminal.
If you just do the cap, rotor, and plug wires, open up to about 0.040" to 0.045".
If you do the cap, rotor, wires, and E-core (TFI Style) coil, you should be able to handle 0.045" easy.
This depends on the quality of the cap, rotor, plug wires and coil you upgrade to...
IF you use premium brass terminal cap, and rotor, and a good set of helical wound plug wires, you should be able to do 0.045" with no problem at all.
IF you use "Ernie's Discount Bargain Basement" aluminum terminal crap and plug wires from China made from old Holiday Inn lamp cords, you probably are going to have problems no matter what plug gap you run.
If you do the rotor, distributor cap, plug wires, ignition coil, and advance springs (Mr. Gasket P/N 925D, $3 from http://www.summitracing.com
) then you are ready for the MSD 6 series capacitive discharge module.
(MSD finds and kills cheap parts in short order! Better use the good stuff!)
With MSD you can go over 0.060", but I've not found any gains in going over 0.060" and for street use, about 0.050" is as large as you want to go.
Glad to see a few were listening....
So many cats, so few recipes...