Plug gap for electronic ignition

[Stu Duglee]

Using a Mallory/Uni-lite distributor (from Mr. T-bolt) & a R-1ish cam, what gap should I try using NGK-V power plugs? Also will be installing 4 BBL soon, does that make any difference to plug gap?

[bezhawk]

It depends on your coil, and to a an extent your wires. if you have sufficent dwell for 40,000 volts then by all means open up the gap to .040 or there about. A stock coil will not produce a hot enough spark as the saturation time of a standard powdered iron core/oil filled coil isn't up to the task.
A modern laminated E core coil has much quicker response time to build higher voltages.
There are induction losses, and differing resistences in coils , supposed to be matched to the ignition resistence ie: the wire resistence, plug resistence and firing resistence(plug gap).
I forget the formula for inductive reactence, It's been a long time since college electronics.
Get a modern coil .
You will be better able to take advantage of a hotter spark and larger plug gaps without burning up your old coil.
A 4bbl would make no difference to your spark as long as the mixture is proper.