TRACING RUNNING PROBLEMS

We're talking here about the engine starting / running poorly, or not at all. The answer nearly always lies with 'the electrics' - the carburettor / fuel side has a few faults, mainly to do with air leaks, as the SU carb is pretty bomb-proof, as is the pump, unless someone has been fiddling with more hope than understanding. But the electrical side of things has many weak points [not least of which is the extremely poor quality of modern condensers - so buy a proper one from 'Distributor Doctor'] and multiple components.