24-02-2020, 08:42 PM
(Usual disclaimer) my recollection from Auto Electrical classes is that an ignition coil with terminals marked SW and CB is theoretically optimised for positive earth return vehicles. Also in theory they should work OK on negative earth return vehicles, however in my experience they don’t always follow theory... I suggest you beg/borrow/steal an more modern one with the terminals marked (+) and (-) , temporarily fit that and see what happens. (+) terminal to battery live of course. Fitting a known good points type distributor is also a good Plan B to eliminate another possible cause. There is plenty of good material on this forum about retiming (or just ask)