Try connecting a temporary wire from the positive side of the coil to the positive side of the battery.
Also you could try connecting a jumper lead from the engine to the negative side of the battery.
Hey Woz,
You said you couldn’t do this because battery in boot, but just a positive to your starter solenoid and negative to engine block or chassis. Cable run from boot needs to be at least 70mm2 or better.
Is your alternator making 13.4 volts and well earthed.
You don’t have something electrical in run position down to earth drawing to much voltage draining voltage from coil.
Have you a good size earth strap from the engine to chassis, use WD40 loosen and retighten.
Have you got good spark, what’s the dizzy again, have you tried to run the engine on Aerostart to see if it’s fuel or spark.
You haven’t done something silly like mixing up the plug leads?
Do you have a bad ignition switch, losing 12V back on run after start.
Have you run a multimeter over everything especially coil and run wire.
Eventually you’ll have to return your carburettor to your car, what is the original carburettor and have you disassembled it yet and is it serviceable. Maybe just something simple! Clogged screen, jets or stuck floats or float valve, incorrect float level etc.
You did mention two carburettors, early in post 1403 (2 step electric chock) and later in post a 1404 (manual chock), The electric chock is preferable if you able to set 12v from ignition switch.
Cheers Phil
Cheers Phil.