Coil connections

Quick one…
Do I take it that the +ve side of a non-balasted coil should have 12v connected to it? The -ve side being connected to the dizzy, or in my case the Aldon ignitor black wire…
Cheers
Tim

That is correct.

OK.
so should I see any voltage on the -ve terminal compared to ground?
Tim

It depends on the position the engine stopped. If the points (or electronic replacement) are open you will get 12V on the -ve side of the coil, if they are closed it should be ground.

Alan.

OK makes sense!
I seem to have a separate black wire coming from the -ve side of the coil.
Would this be consistent with a wire going to the tacho?
Tim

Black is usually a ground wire and from memory the tacho is a white wire with a black to ground the casing.

Tim

It could be, if your tacho has been converted to the voltage sense type. The original current sensing tacho has the white wire from the ignition switch looped through it.

Alan.

Tim,

I believe Alan is correct. Pull the black wire off the coil and see what happens. I’ll bet the car will run, but the tach won’t work.

I think you are all right…
I converted the tacho last year, but stupidly forgot which wires where which…
Tim