I don't claim to know very much about electricity when it comes to all this high tension stuff, but I'm going to throw in a curved ball by way of livening the debate.
This comes from a lovely old boy I was priveledged to know, he lived to over a hundred and was a master of make do and mend, having survived some rather challenging times.
He told me about a trick they use to use on old (petrol) lorries with ageing coils and knackered spark plugs (probably two part plugs) To get a better spark they would cut the HT lead and bare back a bit of copper on each end, then thread each end into the holes in a shirt button and bend it back. So the bare ends are now a few mm apart. The spark then jumps the gap at the shirt button and this apparently makes a fatter spark at the plug... So how come? What's going on there?
You always remember these stories, and he illustrated it with a simple comment.. "You should have seen it with the bonnet up in the dark!". It leaves a mind picture..
