Technical Distributor Points & Condenser: Tuning/Diagnosing Condenser

Regarding gaps: the wider the gap, the more voltage is required to jump that gap. If you ever had an engine with a fouled plug, in many cases, if you remove the plug wire at the cap so that there is a m***ive gap of maybe an inch, more energy is stored in the coil and wires (capacitance and magnetic field) so that when the arc jumps, there is this "capacitive discharge" that is never present during normal operation. The result is that this surge of energy will fire the fouled plug.

Of course everyone knows that for better high rpm performance with a traditional points/cond/coil system, you close the spark plug gap down so that less voltage is needed - this helps because as rpm goes up, the voltage the coil can supply to the plugs decreases significantly.

At Robertshaw Controls, I was testing the first electronic spark ignition systems for stoves. One of the best rigs was a steel sheet where the ignitor leads were afixed to that sheet. This produced capacitance. In many cases, the longest lead an installation might require, if fully in contact with a ground plane, produced so much capacitance, so that when the coil fired, it was unable to "charge this capacitance" to the necessary voltage to fire the ignitor. So we learned that installation should have "loose, floppy wires."

I think places like JC Whitney made Spark Plug Intensifiers which went between the plug and plug wire that was basically a gap (or capacitor) which would "Fire Fouled Plugs" so they claimed. Check out these antique intensifiers:
https://www.collectorsweekly.com/stories/185413-spark-plug-intensifiers

 

Isn't it also true that resistor plugs and/or modern plug wires improve the quality of the spark?

A lot of people believe that solid core plug wires (and lower resistance) are always, always "better", though from what I've read anyway, that ain't the case.

A higher resistance means the secondary or high tension voltage builds up to a higher value before jumping the plug gap making for a hotter, longer lasting spark.

 

Not sure about the resistor plugs and carbon wires. During voltage buildup, there is nothing more than a static charge as far as current goes - there is no appreciable current until there is an arc. Of course, once you establish an arc, maintaining it takes a lot less voltage.

 

The capacitor discharge Pulse Plug: