Spark plug wires 7mm or 8mm

[steveg]

Pertronix Is - I had a coil develop an internal short which fried one; I also attempted troubleshooting by shorting out a spark plug and that fried one. A friend fried one while messing with his coil wires when his car stopped running 100 miles from home.

I do believe they are very reliable as long as one doesn't screw up.

 

[Bob_Spidell]

... I also attempted troubleshooting by shorting out a spark plug and that fried one ...

I believe you, but I can't for the life of me explain how that would happen. As I mentioned elsewhere, the coil effectively isolates the primary ignition system from the secondary--the two never come in direct physical contact unless there's a short--the two circuits are isolated from each other by the coil's insulation; older coils used an oil*, I think our Lucas ones use a paper or coated foil though I've never dissected one. It would take some pretty strong 'back EMF,' which would likely also fry the coil.

Remember the big flap about 'PCBs' a few decades ago? PCBs were/are? used as a insulator (or dielectric) in power line transformers; coils are essentially transformers.