Isn't that "spark intensifier" tip both proven to work, and the principle behind the "Rooster Booster" unit currently on sale?
An extra gap in the HT circuit can make a fouled plug fire on a worn engine that burns oil.
Drivers of petrol lorries used to cut a plug lead and poke the copper cores through a coat button to create the gap.
I'm not sure if it can help much with a distributor, as there is already an air gap between the rotor arm and the terminals.
