HELP !!! Need help trouble shooting my alternator problem

[Hyde440duster]

I have a 72 duster with a 440 set up for the track ( by previous owner) and i want to make it streetable but the alternator is not charging. I have a couple other dusters but they are original engines and 2 are slant six . Where do i begin .. Engine is out of a 68 charger and that is a 1 field wire , and the duster is supposed to have 2 .. i only find on and its not charging where do i start?

 

[67Dart273]

You basically have three choices

1--use the early alternator and put a 69/ earlier regulator on the car. These basically have a ground (mounting), switched ignition, and the green field wire

2--Buy a 70/ later alternator, and make sure it's a "square back" like this:

which will require a 70/ later regulator like this:

They are ground, switched ignition, and green field wire to either of the two field connections on the alternator

The remaining field wire goes to switched ignition, normally a blue push on harness connector

3--Put something else on, your choice, "one wire", Denso, Powermaster, on and on.

 

[BillGrissom]

If you want to re-use your older 1-field wire alternators in your 2-wire system, I think you can install an insulated brush in place of the grounded brush. I haven't tried it, but Mopar put a 2-wire round-back alternator in 70 cars, so the case probably didn't change and I think I read that people have done this. I have bought just brushes at auto electric shops. However, the square-back puts out more current, which you might need if you have an electric fan, ...

 

[67Dart273]

No, different case, Bill. The rebuilders modified many roundback 69/ earlier alternators by drilling one more hole, and installing an "aftermarket" brush. The problem with this is, that the original GROUNDED brush mount was still there, and if it accidently got installed, you either had a fried harness or severe overcharge, depending on which terminal the blue field wire was hooked to

Here, modified "roundback"

I'm not sure WHAT this one "is." It has a grounded brush on the left, and a blank position for an insulated brush on the right. It "sorta" looks like the screw hole is factory, but might not be. Maybe this is a late 69/ early 70 casting??

This one is an obvious "rebuilder hack"

You can see the factory insulated brush at 9 o'clock, and the factory grounded brush at 6 o'clock. The horrid hole at12 o'clock was drilled by a rebuilder. The grounded brush would (hopefully) be removed, and a second insulated brush installed in the "horrid hole." AVOID THESE like the plague. During my 15--17 years as a parts pusher, I saw "a few" of these.

Last, we have a drawing of a 70 isolated field "roundback" so before the "squareback" existed. Notice that there IS NO place for a grounded brush at all. In my recollection, this is the only type I ever saw except for the later, "rebuilder hacks"

 

[BillGrissom]

Interesting. I recall that all round-backs that passed thru my hands looked like #1. I just looked at one off my 64 Valiant and it is #1 type, so must have been from a rebuilder. I can't say any looked like #2 or #3 with a single 2nd position (either a grounded or an isolated brush). I can see the problem if you didn't notice the hard-to-see grounded brush and added an isolated brush.