I'm doing the small cap/external conversion on my 1991 Corvette. I'm using parts from a 1991 F-body with a 350.

I bought an adapter harness from www.jimsperformance.com that makes the 4 wire connector plug and play, so that was a piece of cake.

The other plug on the distributor is a 2 wire deal that goes to the coil. I've ran that to the coil, but I'm curious about the other 2 wiring connections on the coil. Anyone know what they are? Will the car run without the other 2 connections being attached to anything?

Ultimately, I'm using a Mallory 685 ignition box, and I'm struggling getting the correct input to the box. All of the GM external coil instructions for the box use the other plug on the coil for the trigger input to the box. Well, I don't have the other plug because my car came with the large cap/internal coil.

If I understand things correctly (which I probably don't) the plug that I have plugged into the coil right now is the power and ground for the coil, so the car should run the way it's hooked up right now. Is that right?

If that is the case, then I should be able to run the 2 coil wires to the Mallory box, instead of to the coil. That will act as the trigger for the Mallory box. Then, I should be able to make the coil operate using the "Coil out +" and "Coil out -" leads on the Mallory box. That's how you would wire up the box if you were using a Magneto, which isn't 100% correct, but I think it should work. Right?