Wire from coil, where does it belong?

[CaptRamius]

This engine is in a race car, 2.0. The engine top end was rebuilt and returned with the distributor (with no vacuum advance) and an external part with a green wire. I think it’s only an 18 gauge wire. Does it go to a post on the coil or is is it a ground wire?

[Dave at Pelican Parts]

The green wire coming from the distributor is the points signal. It goes from the points to the condensor to the (-) terminal on the coil. Without it, you won't get any spark and the engine won't run. (Unless you're using something else to trigger the spark, which seems unlikely.)

I can't tell which terminal is what on your coil. The wires I see are all aftermarket, and could be just about anything. If you look carefully, one terminal should be labeled "+" and one should be labeled "-". The wire that brings power to the coil should go on (+), and the points wire on (-). The tach signal wire would also go on (-).

Sometimes people who convert to carbs will use the coil (+) connection as a source for switched power for the pump. I'm not thrilled about anything that might somehow take power away from the coil, but that may be excess worry. But that could be one of the wires shown, if that truly is the (+) terminal with two wires connected.

--DD

[CaptRamius]

Dave, that explanation is invaluable, thank you! I will head out to the garage and verify that today.

From memory, I believe the red wire is a power wire, and blue is from the tachometer (it’s electric aftermarket instead of mechanical)

[CaptRamius]

Here are some closeups of the coil pack, it’s a Bosch sold here.
It was a challenge to find and photo but the positive is clearly labeled, thank you for the invaluable information

[Charles Freeborn]

Dave is exactly correct. The points are a "grounding circuit" meaning that they complete the circuit to ground. So, as said they are the link between the negative side of the coil and ground.