I have just had a look at the in-laws 96 1.2 Corsa, they have complained of it running a bit rough occasionally.

I whipped off the distributor cap and the central electrode (if that is what it is called) fell out. It, and the bit it runs in, is worn out.

I confidentally announced that the car would no longer run and put it back together. But it started and revved fine.

How does that work? I thought the HT lead from the coil provided juice to the HT leads via the rotor arm. If so there must be electricity jumping about 10mm.

Is that possible, or am I being thick?

very possble, modern coils can deliver 30 to40,000 volts so a 10mm gap can be bridged quite easily

Wow - I would have put money on it not working. I thought I was missing something.

I am going to replace it tomorrow, but think you could drive it as it is.

Thanks, I am much less confused now.

I had similar engine just months after putting my ZR on the road. On way to Stoneleigh it started to splutter badly on motorway. No carbon bit left inthe cap - just the spring. I stretched the spring and managed to drive a few miles further till i found a motor factors for replacement parts. The first cap only lasted 500 miles or so (both cap and rotor arm were brand new when fitted).

Obviously mine worked cos the spring was still in place.