So, we're finally back on the road, although there's still more work to be done. We cleaned the existing ground and added an additional ground from the alternator case to the distributor clamp bolt. We also cleaned all of the terminals on the starter solenoid. We're still getting residual voltage through the relay that's preventing it from opening when the ignition is turned off, so we ran a wire into the car and installed a switch in the low voltage side of the relay so Joe can turn the engine off. The reason we're going through this trouble with the relay is because DUI specifies a 12 gauge wire to supply adequate current to the distributor. DUI also stresses the need for a good ground, which is why we added another ground to the distributor clamp. We did try running the yellow wires that had been suggested straight to the distributor, and everything works fine, i.e., the engine starts and stops as it should, but I don't want to void the warranty on a $300.00 distributor by not installing it as specified. AMCfool1, I don't see how connecting the distributor power supply to the starter relay can work; this relay is only energized when the engine is being started. I did check voltages on this, and there's only a starter-on voltage, but not an ignition-on voltage.
For what it's worth, both the starter and alternator have been replaced within the last year. We have a new starter solenoid on hand and were going to replace it, but the original solenoid has a single terminal on the back that the new one doesn't have. Starter solenoids like this are pretty generic (it looks just like the one on my riding mower), so I've never seen a terminal like this. Anyone know what it's for?
We only drove the car up and down the block, but I thought it sounded quite a bit better than it has in a long time. At least it's drivable again.