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two field alternator connections

Tipically the grounded brush on one field alternators is the other one, so JUST TO MATCH the earlier assemblies, would ground the other one... Is just about somekind of correctness, not really about if it will work or not. You can ground either one as mentioned.

Of course funknut is showing the other one because he is parting an alt which is already a single field one which it gets just one brush isolated

And no, both prongs are the same size than the existant female terminals on our harnesses ( packards 56 ). HOWEVER, laters alts ( 80s ) usually known as 78 or 80 amps changed the prongs for a tab with a hole to get terminals attached with screws. These are easy to change, using earlier brushes on same mounting assembly

Need to note, from late 70s ( when alt housing changed for a more sealed one ) also changed one of the isolation shape. Brush can be the same but isolator not. If I find a pic will post.

This is just for the records and extra info
 
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Sorry got some problems on previoust post.

This is the tipical two fields terminals setup from 70 up to lates 70s

image.jpeg


I would ground the one of the left which fits the brush vertically against the rotor. Once and again, as mentioned, is just my preference to get it more "correct" with earliers setup.
 
and for added info... On lates 70s, when alt housing changed for a more sealed, the right side isolation on previous post ( the same funknut removed from his alt since this was used on one field alts too ) changed for this design
image.jpeg


The other brush holder remain the same

Alts which used this diff isolation assembly are these

image.jpeg


Note how is the front and back housing are hiding the stator. These are the units using this diff holder/isolation. If you make a close up in fact, you can notice the diff holder
 
In the 80s the terminals ALSO CHANGED, for a setup to get attached fields with screws. I guess because these units get more power output, so it was somehow to guarantee better contact on the input too

image.jpeg
 
And, for more records...

This is the 70/71 alts. Still round back but becoming already in two fields. Some are ready to be matched on single field or two fields systems, and some other already made to two fields/brush/prongs or whatever you wanna call it.

Will post a pic of my post in another board instead post a link
 
Sorry, forgot to attach the pic of my reply

image.jpeg



This would be the real reason why make the job I explained on the pic Pops1967GTX posted. Become a regular single field alt onto a 70/71 assembly
 
Another note on this... Actually all alternators are dual field, since there is no way to produce a magnetic field on rotor able to produce power with just one field... But the single or dual field therm is just know because it gets one or two wires/prongs to feed the fields to the rotor.
 
Shorthorse said:
Sorry moparjohnny, I missed the part where you said you have the electronic regulator. You need to add the dark blue tracer. It would be connected as pictured or really any 12v source that is activated when the key is in the on/run position.

View attachment 345657
Click to expand...
i have a two wires brown and blue coming to electronic voltage regulator on one side,so are you saying cut the blue wire from voltage reg and connect it to a new wire that attaches to the other field plug on alternator?
 
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Darthomas said:
If only one wire is connected to a two connector alternator, no current will flow in the field and no output will be produced from the alternator.
One connection must go to the regulated voltage from the VR, the other must find ground, and if you have an electronic regulator, I would expect you to have two wire in the harness for field connections.
Even so, one is essentially a ground connection.
I have taken two wire alternators and grounded one brush internally to work with the old mechanical style regulators.
Click to expand...
could you explain that a little more in rookie terms
 
Do you have the newer style reg or a electronic old style replacement
The newer style controls the pos side as well as the neg side
to give you a very smooth steady voltage not up and down as the old mechanical one
the replacement electronic reg just controls pos side that is why you ground one brush holder
 
Nacho RT47 has been doing so.
An alternator needs to have a FLOW of current through the rotating field to create magnetism that will cause the outer, non moving windings to have current that will be rectified into the DC that will charge the battery. Think garden hose with spayer at the end of the hose.
If you turn on the spighot, there pressure (voltage), but no water (charging) until the sprayer is operated, providing FLOW or current. So single connector alts have one brush grounded and feed positive voltage to the field connector,
two connector alternators get full 12 volt applied continuously, and control the flow in the field by vary the flow to "ground".
moparjohnny said:
could you explain that a little more in rookie terms
Click to expand...
How did that quote end up in the middle?
And mechanical types need not fluctuate, but adjusting them is bit of a lost art.
I like them because you can decide just how much voltage you want to charge at,
and they have a "base rate" charge set by the resistors on the backside.
And if they "die", they can be opened and convinced to work again almost always, so you can continue with your days plans, even if it's late afternoon on a sunday in the middle of nowhere.
When semiconductors fail, that's all, folks.
 
Darthomas said:
Nacho RT47 has been doing so.
An alternator needs to have a FLOW of current through the rotating field to create magnetism that will cause the outer, non moving windings to have current that will be rectified into the DC that will charge the battery. Think garden hose with spayer at the end of the hose.
If you turn on the spighot, there pressure (voltage), but no water (charging) until the sprayer is operated, providing FLOW or current. So single connector alts have one brush grounded and feed positive voltage to the field connector,
two connector alternators get full 12 volt applied continuously, and control the flow in the field by vary the flow to "ground".

How did that quote end up in the middle?
And mechanical types need not fluctuate, but adjusting them is bit of a lost art.
I like them because you can decide just how much voltage you want to charge at,
and they have a "base rate" charge set by the resistors on the backside.
And if they "die", they can be opened and convinced to work again almost always, so you can continue with your days plans, even if it's late afternoon on a sunday in the middle of nowhere.
When semiconductors fail, that's all, folks.
Click to expand...
PROBLEM RESOLVED I ADDED GROUND WIRE TO FIELD POSITION AND GROUNDED IT TO THE ALTERNATOR CASE,BEFORE I FIRED ENG BATTERY WAS SHOWING 12.5 AND ONCE I CRANKED ENG IT ROSE TO 13.9,CHECKED AGAIN AFTER TURN OFF,AND BATTERY WAS READING 12.44 BEFORE CRANKING A SECOND TIME,SO IT CHARGED THE BATTERY WITH A Field GROUNDED. THANKS
 
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Darthomas said:
And mechanical types need not fluctuate, but adjusting them is bit of a lost art.
I like them because you can decide just how much voltage you want to charge at,
and they have a "base rate" charge set by the resistors on the backside.
And if they "die", they can be opened and convinced to work again almost always, so you can continue with your days plans, even if it's late afternoon on a sunday in the middle of nowhere.
When semiconductors fail, that's all, folks.
Click to expand...

Yes, but if is an emergency on the road, you can also full field the ground ( green wire source ) coming from elct regulators with a jumper wire ( on alt side or reg plug ) and will get your home, mech shop, parts dealer or whetever is your destination safe without get worried. Maybe not completelly safe for the batt, but also depending on how much will the car be drove untill be safe.

You can keep safe the batt thought, increasing the load on the car, driving with high beams, A/C, Radio, rear deffog and whetever load you car gets to suck the extra load added by the full field trick on alt
 
Pops1967GTX said:
On the newer style dual field alternator ,Grounding either field lead will do...
The green field wire from your V reg. hooked up to one terminal. Ground the other field terminal to the alternator case.

I got this from Nacho-RT74 FBBO...
index.php
Click to expand...
followed your instructions and now alternator is charging battery for the first time i added a wire to other field and grounded it at alt case and it started to charge battery right away. thanks
 
Finally got time to try this repair this weekend. Simply removed the plastic/ceramic washer and bent the prong back. Got it all put together and started up the car and nothing. I ended up swapping the voltage regulator with a spare one I had and mission success. So grateful for coming across this thread and yall's support.

image.jpeg
 
This thread has cleared up several questions that I had! I purchased a Powermaster alternator 90amp. It is a duel field , I grounded one field and it is charging. My problem is that the gauge in the car seems to show major spikes in voltage ,that scares me. I suspect the regulator. Could one of you experts recommend a new one for me? Mechanical or electronic?
 
It might help if I gave more info . 1967 GTX 440 MSD ignition and Atomic EFI.
 
To all of you who have contributed both the questions an the answers Holden and I truly thank you. We changed the alternator to day in her 63 Fury to a 2 field from NAPA and had to ground the second field out. Charging issues are fixed. Once again thank you,
 
Good info on this subject. Admins might/should make it a "sticky" for people to have access onthis subject
 
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