Let me confess that I know little about electronics. On my 1976 500 Four I run the green 3 Ohm Dynacoils. They take a bit more power compared to the original coils that rate about 4,5 Ohms. The combination 3 Ohm coils with the original ignition setup will cause your points to pit more. Any transistorized ignition overcomes that problem.
As fas as I know (not much) resistors - wheather they are in caps, plugs or wires, are ONLY there to prevent interference on radio's. By the way, that's enough reason to have them. I have never, never understood what good they can do for the spark. They make it more difficult for the spark to fly. If that's what you want, why not widen the sparkplug gap a bit?
The resistance has more to do with current control in a plasma field than with radio interference suppression. The RF suppression is a by-product of the current control.
In a hi-voltage pulse circuit, the voltage that gets delivered at the gap is a function of the buildup across the gap prior to the jump. If lots of current is availalbe, the magnetic field lines that start the plasma field across that gap allow the current to "escape" easier across the gap while the coil's field is collapsing. If the magnetic lines are limited for a few microseconds by resistance to the current that creates them, then the coil has time to more fully collapse before the gap is jumped. This results in a higher voltage and a hotter spark.
Opening the gap will also limit the current, but unless the coil has a higher voltage potential (known in Engineering as "circuit Q", or "resonance") to compensate for this new gap, the timing of the jump will not be consistent over the whole RPM range. What usually happens is: the timing begins to advance slightly as the RPM rises past the point where a plasma tends to self-propagate inside the cylinder. This would be OK in a typical automotive application where there is no "waste spark" cycle and only 1 plug is fired at a time. But, in these Fours, the 2-plug firing system's waste spark plug then causes the spark timing to lag, compared to the active cylinder's plasma-assisted firing (at high RPM, like 6500+). This lag then "spreads" the coil's collapse over a wider time, which drops the voltage peak and advances the timing a little. This "wandering timing" effect can be watched, if you have a setback timing light and can switch back and forth between a "resistored" system and a non-"resistored" system, so you can check it out yourself: that's how I came to first believe it back in the 1960s.
Does that help?
