Triumph Repair: Electrical:, spitfire mk, gauge wire

Question
Is the 64 Spitfire4, 6 or 12 volt and is the system, positive or negative ground?

Answer
Hi Bruce,
The 64 Spitfire Mk I & Mk II were 12volt positive ground unless someone changed it to negative ground to use an alternator and/or a later model radio. The ordinal car was positive ground and should have a DC generator and a positive ground radio. Either system was 12volts.
There is a way to tell if the generator was polarized to be a negative ground.
You need to make up a test lead out of a heavy 12 gauge wire that will reach from the back of the generator to the battery post. The test lead must connect to the larger of the two posts on the back of the generator and make a short jumper from that large post to the small post. With the fan belt off connect the battery positive post to the ground strap then touch the end of the test lead to the negative post of the battery and watch the generator pulley as it will start turning like a slow electric motor and if it is turning in the direction the motor normally runs, it is for sure set up to be a positive ground as it was originally. If the generator turns the opposite direction then someone has reversed the polarity for some reason, most likely because of a late model radio.
If someone has installed an alternator in place of the generator then it has to be negative ground.
I hope this helps.
Howard