Alternator ground question.

[jmbass98]

Thanks guys.

Would a modern style regulator like this function better in my setup than the original mechanical one?

https://www.autozone.com/batteries-starting-and-charging/voltage-regulator/p/duralast-voltage-regulator-vr706/129965_0_0

 

[jmbass98]

Also the alternator pictured is listed as a 62-69 replacement part on the Layson's site. Is that not accurate then?

 

[jmbass98]

More I'm reading is that the stock mechanical points-type voltage regulator can cause issue with Pertronix?

 

[RJRENTON]

Having charging issues. Got a new alternator from Layson’s. Has two field posts on the back. Is this the right style of alternator? Does one need to be grounded to the case for proper function? If so. What gauge ground wire to use?

Points. Mechanical voltage regulator. ‘66 Charger.

View attachment 1293141

Your choice.....you can ground EITHER one of the field terminals, it matters not, and the system will work just fine. BTW...the alternator is an ISOLATED FIELD UNIT origionality developed for 1970 and newer vehicles, using the Electronic voltage regulator. It will function just fine with your mechanical voltage regulator.
BOB RENTON

 

[jmbass98]

First just check at the battery.
Should be around 12.5-12.7 just sitting there.
Next after starting maybe 13-13.5 (depends on the alternator, battery and how fast your idle is...)
Finally speed up the engine and it should head towards 14V
But the ammeter will tell you a lot as well.

Alternator battery cable post reads 11.7 on idle.

 

[jmbass98]

Swapped alternator and grounded voltage regulator to block. Now getting 13.9v ish at fast idle. Yay. But now I’m getting some belt squeal, especially at RPM… what does this indicate?

 

[jmbass98]

Yeah that squeal is super bad. Belt gets extremely hot. I loosened it a reasonable amount. Didn’t squeal as bad at idle but still did with RPM. Tightened it to max, made it worse. Is the pulley bad?

 

[jmbass98]

Battery was pretty low when I started the car (prob around 11.6v key off). Would that cause the alternator to overwork, producing squeal on the belt?

 

[Some Car Guy]

More I'm reading is that the stock mechanical points-type voltage regulator can cause issue with Pertronix?

My Petronix is fine with a mechanical reg

 

[Don Frelier]

The belt should be quite tight.
Is the pulley aligned with the engine pulleys?

 

[jmbass98]

Solved... Pulley was slightly off alignment. Readjusted everything and now it works.

Charges for the first time in a year! Thanks everyone.

 

[Stumper]

I need to tag onto this thread with a question. I just had to replace the alternator on my 62’. The “exact fit” that I received from Advance is a dual field. While replacing the alternator I also changed out the regulator to one of the transistor reproductions from Classic Industries. I left the one terminal open and everything seems fine. I tried to take the nylon spacer off to let it ground itself but this is the nylon bracket that holds the brush so that’s not an option. I ran a wire off the terminal to ground to see if it makes a difference but it doesn’t seem to? Is there any issue just leaving that terminal alone and not grounded?

 

[RemCharger]

If.. the new regulator is a single field, and..it's charging regardless of grounding the 2nd field terminal.. then that terminal must be grounded. A simple continuity test would confirm that.

 

[Stumper]

If.. the new regulator is a single field, and..it's charging regardless of grounding the 2nd field terminal.. then that terminal must be grounded. A simple continuity test would confirm that.

For us electrical dummies - test terminal to ground with no current on? If so I show about 9-10 ohms?

 

[Dragon Slayer]

To test disconnect the wires to the two field terminals. Measure each terminal to the case. Should read open if a true ungrounded alternator meant for the 70 up electronic regulator.

If it reads a ground it should be closer to 0 ohms. The mopar fix was to add a jumper wire to one terminal and screwed to case to ground one side. For use on 69 under single field units.

 

[Stumper]

To test disconnect the wires to the two field terminals. Measure each terminal to the case. Should read open if a true ungrounded alternator meant for the 70 up electronic regulator.

If it reads a ground it should be closer to 0 ohms. The mopar fix was to add a jumper wire to one terminal and screwed to case to ground one side. For use on 69 under single field units.

With my $20 multimeter - I show zero ohms on the unused terminal and 4-5 ohms on the other? Does that seem right?

 

[RJRENTON]

With my $20 multimeter - I show zero ohms on the unused terminal and 4-5 ohms on the other? Does that seem right?

YES.....Zero ohms shows that this terminal is grounded and the other terminal is reading the rotor's winding resistance including the slight resistance of the carbon brushes. imo, you will be good to go.....
BOB RENTON

 

[Stumper]

No benefit of grounding that terminal to the case then?
Thanks!

 

[71_bronze_gtx]

The alternators used circa 1970 with 2 field terminals connect as follows:

One field wire connects to ignition hot +12 volts. This is the supply for the field winding.

2nd field wire connects to the electronic regulator. The voltage to this terminal is regulated by the regulator to control the amount of charging current.

The B+ or battery connection (the bolted one) is the output of the alternator, going thru the ammeter to the battery.

Ground connection for the alternator is via its case/frame being bolted to the engine block, which is grounded.

 

[oldmangarth]

See post #4

I've been running the solid state with a dual field for 25 years.
They work better.

Do you have a picture of the solid state voltage regulator and how it's wired with the dual field? That's what I'm trying to do with my 67 charger but don't know how to do it. This is mine now "before" I change to solid state. FYI, I checked continuity from both fields and both are open. Just don't know where to connect the second field.