A Puzzling Problem.......

[David53]

As mentioned earlier it is only happening with a sustained high rev such as when cruising at high speed in top, and is under load.

For the sake of a few quid I would be replacing the dizzy cap. A tiny crack could well produce these symptoms when the rotor is whizzing around at high speed and constantly. It is possible there is an arc between two of the contacts. Like I say, for a few quid worth a shot

[MarkyB]

Just checked in the manual and 1 pint (.57 litre) per minute it is!
I must have read it when there was still some storage space left in my brain.
Only needs a minute or so to check. Tools a screwdriver, a petrol proof container of over 1 pint and a watch with a second hand.
A beautiful (or otherwise) assistant could be handy or you could fly solo.

[mrmorrisminor]

Well.... we gave up on this for quite some time after trying almost all the suggestions above, it seemed a good way of limiting the somewhat enthusiastic driver to a sensible speed.

The car has covered another 2000 or more miles until..... the other night on the A2 (on the steep hill near BlueWater shopping centre) it died.....

The wire connecting the coil to the distributor had melted itself completely through about an inch or so from the spade connector. We chopped it down a little further and reconnected a new spade and off we wnet and the original problem seems to have been cured.....

So it would seem that there was a break in the wire which was probably getting warm under load as you took the car to higher speeds and was failing intermittently, until it finally burned through!

Something sooo simple after all!

[MarkyB]

Only simple to find if you happen to have X-ray vision though .