1 FIELD TO 2 FIELD ALT

[WAYNE0]

When i bought my 67 barracuda i noticed that someone put in a newer engine bay wiring harness. Not sure what year the harness is. Its a electronic ignition wiring harness. Its also has 2 field wires for the alternator. I have a used but very new 1 field wire alternator that i would like to use. Can i some how use that 1 field wire alternator on my 2 field wire harness ?

 

[Dana67Dart]

Yes but it will require so adapting the harness.

In a 2 field wire setup the blue wire provides 12v to one of the field wires and ( I think) one of the electronic voltage regulators terminals (the VR has to get switched 12v from somewhere)

The green wire goes to one of the electronic voltage regulators terminals and to the other field wire.


To convert to single field wire setup you need to feed the electro mechanical voltage regulator "I' terminal with a switched 12v feed ( might be the same that feeds the ballast resister, your cars wiring diagram will show)

Then modify the green wire to go to the F terminal on the VR, then to the single filed terminal on the alternator.

You might want to add the wires leaving the wires in the harness unmolested.

If you get a 70(????) up wiring diagram that has the electronic VR and compare it to your cars wiring diagram you will see the differences

 

[AJ/FormS]

Be advised tho, that the Electro-mechanical regulator, being a glorified set of points, they can stick in the "on" position, and when they do, the alternator goes into overdrive. It's output increases directly with rpm, until it cooks everything. If this happens at night, and the headlamps take the first hit, well there you are on the side of the road.

BTW
The way that the older VR works is by continuously turning the alternator field circuit on and off, to keep it's output in the magic window that the battery can work with. Because it is continually switching, the points experience metal transfer from one side to the other, and even erosion, and eventually, they either wear out or naturally become unreliable....... or fail in the "on" position welded permanently in that position.
Whereas
The electronic VR has a transistor doing that job with NO moving parts; and they rarely fail, unless the case loses ground, and then they fail in the "open-circuit" mode and you drive until the battery runs out of juice. At night, the lights just get more and more dim. If you see it happening, you just go fix the ground and all is back to normal.
Since 1970/71 I have only ever had one Electronic Regulator fail in the "on" condition, which then caused the voltage to spike at 20 volts..... and this was a Mopar Constant Voltage one that I bought out of the DC catalog. Silly me..... lol.

 

[67Dart273]

When i bought my 67 barracuda i noticed that someone put in a newer engine bay wiring harness. Not sure what year the harness is. Its a electronic ignition wiring harness. Its also has 2 field wires for the alternator. I have a used but very new 1 field wire alternator that i would like to use. Can i some how use that 1 field wire alternator on my 2 field wire harness ?

This is a misconceived idea. Especially now, with poor availability of QUALITY older car parts, the 70/ later VR is a FAR BETTER design.

Post a photo of your alleged grounded field alternator. Many of them are actually "not" that is, can be converted. Otherwise, I'd replace it and move on. Also, electrically, the "square back" designs are better.

However, Dana is making things a bit too complicated. All you have to do is install the old style VR, clip off the connector for the later VR, and hook the blue to the IGN terminal, and the green to the F terminal of the old style VR. Connect the green to the field of the alternator, "safe off" the blue that "did" go to the second field terminal, and you are there.

 

[cudamark]

Or, just get the later 2 field alternator if your wiring is already in the car and working. Some alternators can be converted from one wire to two depending on the year and how it was rebuilt. We would need detailed photos to determine that.