Running Problem

[Matt7c]

Back to the original question, are you sure the snag is heat related. I recently had a similar problem, but it was caused by a restriction in the fuel pick-up pipe in the fuel tank. This meant that after a few minutes of running (coincidentally when it was hot, though this wasn't a factor) the fuel bowl in the carbs ran dry. Naturally, this symptom is easy to check for by looking at the fuel level in the carbs when it has stopped (assuming your floats are correctly set).

[Hamish Coutts]

Absolutely agree with Matt7c.
I chased a fuel problem for ages eventually to find that there was a piece of rag stuck in the fuel pipe that was partially blocking the fuel supply. If the engine was ticking over there was enough fuel flow to fill the float chambers. With a bit of throttle the float chambers gradually emptied and then stuttering and coughing and eventually a dead engine. Very frustrating!
I have an electric fuel pump.

Regards,

Hamish.

[cliveyboy]

The later Sprints did use a ballasted system as mine has one.
I have also been using electronic ignition with it and had no problems.
Clive

[M100]

Leave the fuel filler cap off and see if that helps

Regardless of ballast coil or not i'd get ANY known good non ballast coil, wire it direct to the battery not through any immobiliser/ignition switch etc, provide a dedicated earth from the engine block to the battery (jump lead) and also use a points actuated ignition with a known good condensor

If it dies then

a) check the fuel pump bowl (if glass) for fuel
b) remove the float chamber cover and check for fuel
c) check spark plug insulators to see if there is any radical temperature spread
d) remove spark plugs and check for fouling

[wobblyweb]

Thanks for all the suggestions.
It is looking like a sticky exhaust valve.

I will post when that is fixed and see if it is cured.