Rewiring Car, Alternator Connection questions..

[72Duster440]

So I have decided to rewire my entire car, 72 Duster with a big block. I've got most of it done, but I am a little confused about the ignition/charging system. I have a 3 wire alternator, external regulator, ballast resistor and an MSD box. I am looking to remove the ballast resistor, but am unsure where the alternator field wires will go now. All of the diagrams I find online so them going to the ballast resister and coil, which is no longer valid with an MSD box. Do I just hook them both to the regulator and then splice into the power wire and run a jumper to the starter relay?

 

[67Dart273]

Basically you hook "all wires" together there at the ballast and things takes care of themselves.

If you have an original 4 terminal ballast, one of the wires also goes to 12V and the other goes to the ECU. Both these can be eliminated.

The old coil POS wire now goes to your MSD "small red." The big red and big black go to ground, and to the starter relay "constant" 12V. I would fuse that wire.

The "truth" is that functionally you could leave the ballast alone, and hook the old coil + wire to the MSD "small red" and it would work fine. The small red is a low current "trigger" wire just like a relay

By the way MAKE CERTAIN you do NOT have anything hooked to the coil, NOTHING except the two new MSD wires. No tach, and no radio condenser / capacitor.

 

[72Duster440]

I have 4 terminals on the wiring side, but only 2 terminals on the ballast, so two of the wires aren't connected. I'm installing a Painless harness to fix a lot of the electrical gremlins I have and wanted to eliminate the ballast. I understand what you are saying, and hooking up the MSD makes sense.

There are many non factory splices in the blue field wire, I'm trying to figure those out. It currently has two wires coming off of the ballast, one goes to the coil (MSD box)(14ga br) the other goes through the bulkhead to ignition 1 on the column (14ga br). Prior to the ballast it has a splice that goes to ignition 2 on the column (16ga bl), and the regulator.

So would I be able to run the wire from the alt field to the regulator, with a splice that powers ignition 1, ignition 2 and my MSD trigger?

Edit: A picture makes more sense... This is how it's currently wired.

 

[72Duster440]

This is what I think I can do.



I also find it off that the wires that feed the ballast are 18 gauge, but the ones coming out of it are 14. Do I need to run a 14 the whole length now? I think the painless one is a 16 and I'll have to add the second one, since there is only 1 field wire in the new harness.

 

[67Dart273]

You sort of lost me. If you are using a Painless harness, then why worry about how it "was?" Your bottom diagram is right except what you labeled as "coil." That should be going to the MSD "small red". The painless box has two wires which hook to the coil. ONLY those two wires from the MSD should be hooked to the coil

 

[72Duster440]

Perfect, thank you sir. I just wasn't sure if I needed to copy the way it was hooked up. The Painless harness is their universal hot rod one, so the wiring is set up a little different than what I had. It sounds like I should be all set now, thanks.