10-06-2018, 11:29 PM
I ought to know the answer to this but car electrics have never been my forte. If your coil has + and - terminals then for a positive earth car + is earth and thus the wire goes to the distributor and - goes to the ignition feed, and vice versa. All the A7 coils I have seen simply show SW or CB, not + or -. But when Sevens changed from negative earth to positive earth in 1935 did the coils fitted have their terminals changed round? If so how do I know if I have a post-35 coil or a pre-35 coil? I know it's not a disaster to fit them the wrong way round but it does not produce the stronger spark if you get it wrong. Or am I talking rubbish?