Bizarre Plug Problem

[Jessie The Jeep]

Before my trip to Breighton airfield, I re-gapped all the plugs and fitted a new condensor, while waiting for my new electronic ignition system to arrive. All was well on the 200+ mile trip.

 

I then fitted the Jolley Engineering electronic ignition system, and the running was even better than before. I drove around 120 miles with the new system without issues; then on Friday gone, 1/2 mile from home and on the motorway heading for the Croft event, the Jeep started running really rough, loss of power, coughing and banging. I checked all the leads for sparks etc and all worked, so pressed on to get to Croft as I didn't want to stop on the hard shoulder.

 

After much head scratching as to what the problem might be, I removed all the plugs to check the gaps, even though they can only have done less then 500 miles since the last gap check. Number 3 had the electrodes flattened and touching, hence no spark!

 

What could have flattened the electrodes? The engine was turned over without and grinding or scraping noises, so I didn't think a ring had disintigrated. After resetting the plug gap, the engine ran perfectly again, and did so all the way home.

 

Any ideas on what happened? Something seems to have thumped the electrode to push them together, but what?

[Tony B]

Glad not only me. I changed the plugs on the Dodge the other week. Number six, the one by the firewall blew clean out! Did the plug thread but not the engine, thankfully.

The only time I've seen plugs close was on go-karts. The plug batch was defective and the elctrode was getting to hot and bending.