Round back alternator ID

[rmchrgr]

Trying to figure out what alternator I have here. Looks to be a re-man unit. Has this been converted to dual field? The 9:00 field terminal is grounded to the case under the wire clip.

This alternator came off my '68 Coronet when I converted it to EFI and was replaced with a modern Denso alternator. Before the EFI conversion, the car was running a Pertronix ignition dual-point conversion. It was being used with a Wells VR706 regulator. Seemed to work OK.

Anyway, I'm asking because if this combination of parts will work, my friend and I are going to use them his '66 Fury which we're converting to a big block equipped with your garden-variety Mopar electronic ignition.

Thanks for any input.

- Greg

 

[Jerry Hall]

As far as I know in 1970 the round back alternator became a dual field through the end of its production. By grounding the second field it can be used on the earlier cars. I may be mistaken on the year of the change but I'm certain 1970 was a dual field. My 62-68 cars are the single field units.

 

[R413]

That is a stock alternator for 1969 and older. You can use it on the 66 Fury.

Yes they grounded the other brunch like that.

Jerry has the dates right for dual field.

 

[Jerry Hall]

That is a stock alternator for 1969 and older. You can use it on the 66 Fury.

Yes they grounded the other brunch like that.

Jerry has the dates right for dual field.

Thanks, believe it or not I don't have a 69 Mopar, so I wasn't exactly sure.

 

[Nacho-RT74]

That's a 70/71 alt. Round back dual field. Hard to come by latelly. 72 become on square backs

Grounded to make it work as a single field.

Original single field roundbacks ( pre 70 ) look like this

note the grounded brush on opposite side, without the isolator, attached straight to the case

Some alts were disposed to accept both setups... note this case

So If the alt was to be installed on an older single field setup, the isolated brush was replaced for a non isolated brush on the opposite provision

Single field round back alts can be also converted in dual field just drilling a couple of holes to provide the location for the other isolated brush assembly ( and its attaching screw )

 

[Nacho-RT74]

As far as I know in 1970 the round back alternator became a dual field through the end of its production.

actually I think by the end of 69 some C bodies already got a dual field setup. They even got a very weird regulator with 3 pins instead two ( hence the reason why these plugs are triangular )

on 70 all models were already assembled with dual field and elect reg

 

[Nacho-RT74]

Yeap! 69 C bodies... only year ( and models ) with 3 pins electronic regulators

https://www.forcbodiesonly.com/mopa...ge-regulator-2875400-the-3-pin-special.19314/

But it seems still single field alts

 

[rmchrgr]

OK, so if I'm understanding correctly, we do in fact have a later dual field alternator here which has been grounded to work on a '69-older car as a single field.

To run this unit on our subject '66 Fury, we will install it with the 2nd field grounded like it is now and will use the Wells VR706 updated electronic regulator that works on the older cars. Since we're converting the car from a small block to a big block, we're going to get a new big block wiring harness updated with the electronic ignition connector already in it.

Are there any caveats to using the dual field alternator with one field grounded and an electronic ignition? Will we have to modify any part of the ignition/starting or charging harness or just install as-is?

 

[Nacho-RT74]

The grounded brush on that one is the same than have the previous single field setup. If you are going to match it with the old style regulator no matter if still mech system or the newer upgraded electronic system into the old case you will be fine with the existant wiring and setup

Now if you wanna to complete the upgrade for the newer electronic setup and dual field, just need to get the later regulator, remove the ground jumper on alt and splice a new wire ( blue ) to run to the alt and regulator pigtail.

This is a very well known diagram easy to find around, that I colored looong time ago and is now being posted everywhere LOL


Electronic ignition is not directly related to the electronic regulator system, HOWEVER is tipically adviced to get both upgrades at the same time, since the electronic ignition will be grateful with an electronic regulator system too. More efficient and without current "noises" due the mechanical regulator system.

 

[rmchrgr]

Thanks. This is the regulator we will be using, Wells VR706 which is what most people use when dealing with the pre-'69 type of setup. Same exterior connections as the mechanical but electronic inside.

Frankly, I kinda don't want to get involved with changing to dual field. I know it's a pretty straightforward exercise and I even have a few flat style regulators already but this project needs to kept as simple as possible.