403 Sparking plugs

[Geoff Dowdle]

Graham ,
The details of the NGK Plugs given by Dave Dale are the wrong way around .
The C6HSA is suitable for Touring engines and hotter than

C7HSA which is suitable for Sports engines and are a colder plug.

How have you checked that the mixture is correct??

With old original Solex carbs , often the float level is too high which can flood the idle circuit and foul the plugs.

Many Electronic ignition systems only take the place of the points and condensor .
A points distributor in excellent condition should not cause any problems .
Many ignition problems with Lucas distributors are in the bob weight system that advances the ignition when the engine speed increases .

If you have previously needed to fit C5HSA (Hot) plugs to your engine , I'd imagine there is some other problem which is causing the fouling.

Geoff