Jumping alternator gauge needle on factory gage, 67 GTX

[AR67GTX]

I installed a NORS mechanical voltage regulator (from Halifaxhops) on my 67 GTX today in order to replace the solid state one that was putting out 15 volts+. It’s allowing a charge fine and I’ve about got the voltage dialed in to where I want it but the alternator gage needle is jumping constantly. It was steady before. It’s staying to the right slightly - not going into discharge. I thought maybe it would settle down after the battery was charged back up, from when I started the car. But I ran it quite a while and it didn’t settle down. I don’t see any big jumps on my voltmeter which is hooked up to the battery - just the usual .03 to .04 volts variation.

So what causes amp gauge jumpiness? The regulator points contact were cleaned with electrical contact spray, no-ox applied to terminals, mounting screws are tight. I’ve got a few other regulators I can try if this one I no bueno.

 

[Sinitro]

It is showing the regulator cutting in/out, most likely the battery is fully charged.
To check things out further, turn just the headlights ON for about 10 minutes then start the engine the amp guage should read to the rite indicating charge for a few minutes until the battery voltage is back up to spec..

Just my $0.02...

 

[ruffcut]

Very normal for that regulator. My Roadrunner does the same. ruffcut

 

[AR67GTX]

I’ll play around with it a little more. I just did the same thing on my 66 (replace 15 volt solid state reg with mechanical VR) and it jumped a little when I first started it but quickly settled down to where the needle was steady. The 67’s alternator is only 4 or 5 years old and has been working fine. I’ll see if this one settles down.

 

[hunt2elk]

Are you running points or electronic ignition? Just asking because I have heard that the old style mechanical regulators don't always play nice with electronic.

 

[AR67GTX]

I’m running points - all factory stock.

 

[monaco66coupe]

at nighttime are your dash lights flickering in time with the gauge flutter?

 

[AR67GTX]

Haven’t had it out at night but I did notice a slight rhythmic dimming/brightening of the under dash curtesy light while letting it idle.

 

[monaco66coupe]

My 69 coronet is doing the same thing,years ago my fusible link blew on another car I no longer own,,,,so I am cautiously looking through everything in the dash, I will speak up if/when I find anything.
It has to be something running off the key,(short, or alternator problem) as it does not do it with power off, thank goodness.And I have replaced the regulator with one in good working order from another car with no change. I installed a good ground strap, and the problem has decreased, but not stopped,,,,as yet.
It's like a hot wire bouncing and touching a ground somewhere,, but the car isnt moving,,,,,so?

 

[AR67GTX]

Played around with it some more and went for a short ride. It’s doing a little better but when I turn on the lights it really jumps around as shown in the video. I also checked all the alternator connections, put some No-Ox on all of them, put a star washer on one of the VR bolts and ran a ground wire to the battery post.



I found an old electronic VR and tried it but it was dead. Tried another old mech VR I had but it jumped around even worse. Put an old, small chrome can, electronic VR and it produced a steady needle but was putting out 15.2 volts. Finally gave up and put the electronic VR back on it that I’ve been running for a few years, but it puts out 15 volts. Hasn’t burned anything out yet so until I find some other option.

 

[AR67GTX]

I’ve been playing around with mechanical and electrical voltage regulators on my 67 since my last post and consulting with Halifaxhops some and we’re stumped. The car (67 GTX) behaves fine with an electrical voltage regulator - it just charges at 15.3 to 15.5 volts - to high IMO. I’ve tried a couple different mechanical regulators on it that work fine on my 66. Here is what I’ve done:

- verified the amp gauge connections are tight
- pulled the bulkhead plugs, cleaned with De-Ox and treated with No-Ox conductive grease - contacts were cleaned up years ago and continue to look brand new.
- checked water levels in battery cells - all good - none needed
- pulled ignition switch from plug, cleaned both with De-Ox - put back together.
- checked field connection at alternator and verified tight.
Afterwards tried one of the tried and true mech VRs I used on my 66 and still have a dancing amp gauge. Here are my voltage checks. The thing that seems off is the low voltage on the field side of the voltage regulator and the voltage fluctuations from neg battery to Ign side of the VR. It’s a rebuilt alternator, maybe 5 or 6 years ago. Sort of suspecting it has some weakness ( maybe diode?) that an electronic VR masks but which mech VR doesn’t play well with (?). Both cars running points. The 66 has all new wiring. The 67 has all original wiring, very few repairs and everything works.

Anyone have any thoughts on this. I would really like to get rid of these high voltage, voltage regulators. I have 3 of them and they all put out over 15 volts.

 

[AR67GTX]

BTT - got the name of a good, local alternator rebuilder so planning to pull it out and let him look it over.

If anyone has any other thoughts on wiring/connections checks, please let me know. The Bat (-) pole to VR field terminal voltage reading (12.87) seems really low compared to battery voltage (14.4) with the mechanical VR. Even with the solid state VR it’s low compared to my 66 Sat.

Ed: just realized I didn’t run some of my voltage checks correctly so back to the garage.

 

[RJRENTON]

I installed a NORS mechanical voltage regulator (from Halifaxhops) on my 67 GTX today in order to replace the solid state one that was putting out 15 volts+. It’s allowing a charge fine and I’ve about got the voltage dialed in to where I want it but the alternator gage needle is jumping constantly. It was steady before. It’s staying to the right slightly - not going into discharge. I thought maybe it would settle down after the battery was charged back up, from when I started the car. But I ran it quite a while and it didn’t settle down. I don’t see any big jumps on my voltmeter which is hooked up to the battery - just the usual .03 to .04 volts variation.

So what causes amp gauge jumpiness? The regulator points contact were cleaned with electrical contact spray, no-ox applied to terminals, mounting screws are tight. I’ve got a few other regulators I can try if this one I no bueno.

IMO.....because it's a mechanical voltage regulator, it regulates the alternator's rotating field windings by applying EITHER: 12 volts, ~ 8 volts and zero volts, in response to the battery's state of charge. The switching action occurs fairly frequency.....on/off/on/off....and its totally dependent on the mechanical aspects of the voltage regulator 's spring tension, voltage sensing coil resistance and the external resistors that are under the regulator. This is why the electronic voltage regulator replacement is better due to the internal transistor providing even stepless switching of the alternator's rotating field power. The internal voltage divider network of the regulator may be a little generous, hence, a slightly higher system voltage.......just my opinion of course.... Its difficult for the mechanical voltage regulator to be accurate and as smooth as the electronic voltage regulator
BOB RENTON

 

[AR67GTX]

You may be right but I tried a mechanical VR from my 66 that was dead smooth on it (amp gauge needle steady) but when I put it on the 67 the the gauge needle jumps all over the place and the lights are flickering. That, and my already somewhat higher voltage loss from the battery to the VR field gets even worse. Yet, somehow - except for a little too much voltage loss - with the electronic VR installed on the 66, the amp gauge is steady as are the lights. Both cars are pretty stock with standard single field alternators and points distributors.

My thinking has changed now, and I think I need to follow the FSM test for trying to find the source of the voltage loss on the battery to VR circuit. The starter is the main item I haven’t inspected and cleaned connections on so I need to get under there and do so. Hope to do that today. If that doesn’t fix the issue then I’ll have the alternator checked. Really like to get away from the electronic voltage regulator since I have 3 of them and all are putting out between 15.3 and 15.5 volts.

thanks

 

[RJRENTON]

You may be right but I tried a mechanical VR from my 66 that was dead smooth on it (amp gauge needle steady) but when I put it on the 67 the the gauge needle jumps all over the place and the lights are flickering. That, and my already somewhat higher voltage loss from the battery to the VR field gets even worse. Yet, somehow - except for a little too much voltage loss - with the electronic VR installed on the 66, the amp gauge is steady as are the lights. Both cars are pretty stock with standard single field alternators and points distributors.

My thinking has changed now, and I think I need to follow the FSM test for trying to find the source of the voltage loss on the battery to VR circuit. The starter is the main item I haven’t inspected and cleaned connections on so I need to get under there and do so. Hope to do that today. If that doesn’t fix the issue then I’ll have the alternator checked. Really like to get away from the electronic voltage regulator since I have 3 of them and all are putting out between 15.3 and 15.5 volts.

thanks

The physical attributes of the two systems are slightly different creating differences and it affects/performance. A voltage drop test is always a good idea although a few tenths of a voltage may difficult to pinpoint. The difference MAY BE due to brush connections, rotor resistance, slight difference in diode conduction, stator impedance, etc. and of course the difference between "identical" systems and mechanical voltage regulator manufacturers tolerances....just my opinion.....
BOB RENTON

 

[kiwigtx]

"Jumping alternator gauge needle on factory gage, 67 GTX"​

There's that word again.

 

[AR67GTX]

Yeah, I know gage is kind of a slang reference interchanged with gauge and sometimes I slip up and sometimes I think I fat finger it and Ipad doesn’t catch it. I’ll try to do better.

 

[AR67GTX]

On this particular car, Halifaxhops helped me identify in mid-Jan that although an alternator rebuilder tested my alternator and pronounced it good by test, it was non-the-less probably producing a bad DC signal to the VR. I looked around for a source of another rebuilt alternator that I felt I could rely on and got it installed today. It has fixed my jumping alternator gage issue i was having with a mechanical voltage regulator.

So now I’ve successfully converted both my 66 and 67 from 15.2-15.5 volt output electrical voltage regulators, to mechanical voltage regulators adjusted to put out around 14.1-14.2 volts warmed up. Finally.