Sudden failure of distributor rotor

So during COVID lockdown both my cars are in the garage. To get the Wolseley Hornet out in the sunshine I have to move the XJS out first.

I did that yesterday evening and left the XJS idling while I drove the Hornet out and fiddled with the doors. When I got in the XJS to reverse back in as soon as pressed on the throttle the car cut out and would not restart. A few mild moments of panic as I am now blocking a shared laneway that gives access to all my neighbour’s garages too.

Fuel pump is whining for a couple of seconds when the key is turned so I start looking for a spark. Nothing on the plugs. Check the king lead - get a shock - get some wooden tongs and check the king lead again - good spark. Change the rotor for an old one I keep in the boot (trunk, not my shoe although can any of us say we don’t carry spare parts in strange places just in case when we drive a Jaguar?) and the car starts immediately on next attempt as if nothing ever happened.

I am just surprised that the dizzy rotor would just have such a sudden failure and go from perfect idling to dead as a door mouse in a second.

Anyway it proves that the old cliche that if you carry a spare part you will never need it is wrong!

had a 66 MGB. Tooling down the road in rural Georgia about 55 mph one evening in 1968 and car quits about 10 miles out of town. Long story short is that it turned out to be broken rotor.
On my XJS I was replacing ignition wiring and dizzy cap. Looked inside dizzy cap and it was a mess of “plastic thread” because one tip of the rotor tip was contacting, and eating away ,the plastic of the cap. I was lucky in my timing of deciding it was time to replace these components.
Gonna follow Sbobev’s advice and keep spare rotor, cap coil, and amplifier in the boot

Had it happen a fair bit, especially as rotors got to be of lower quality, in the 70s and 80s.

It’s part of the reason I am GLAD distributors and carburettors are gone.

My dad’s S1 XJ6 broke down not far from home and, on the side of the road, we diagnosed a spark problem. The spring in the centre of the dizzy cap that pushes the coil lead connection onto the top of rotor had expired. Managed to fix it with the spring from a ballpoint pen and get us the last couple of miles home.

Series 3 E-types were, in the early years, prone to this problem. The new OPUS ignition produced such a hot spark it would burn through the rotor to the dizzy shaft, shorting out the ignition. Happened to me on two occasions. First, driving down an Alabama back road the tac went to Zero and the engine quit. Analyzed and found no spark from the plugs. Car towed back home. Later found rotor shorted and it cracked the dizzy cap too. Second time, cruising on an Interstate same process. Tac snapped to zero and motor quit. Would not restart. Changed the rotor and all was fine. Always carried at least 2 new rotors and 1 dizzy cap - just in case!!! Hard part was getting to the dizzy cap to remove it - on the side of the road… But we love’em anyway.

Happy Trails,


I’m not familiar with the 4.0 AJ6 rotor. What d’ya suppose is under the red potting?