[Rusty63]

Since changing to a Autozone solid state voltage regulator, I was told the small hole on the side (opposite to the four posts) is for a ground wire to be placed.

I had it with just the three mounting screws (with rubber isolators) holding it to the core support, and then attached the harness, no ground.

The car runs, but should it have a ground wire added? Seems contrary to having those rubber isolators. Clearly, not Mr. Electrical, here...:turn:

Thanks for any suggestions.

-Rusty

 

[drm101]

If it's charging, you are probably all set. You can check that with a volt meter connected to the battery. With the car off you should have around 12 volts. Start it up and you should have 13-14.5 volts. It can't hurt to add the ground strap, though, and it might make the ckt board in the voltage regulator less susceptible to electrical spikes that could damage it.

 

[Rusty63]

Okay, perfect. Just didn't want to do any harm.

Have issue of dash lights/ dome light, headlights pulsing, brighter when pushing gas pedal. Connections on headlights dirty; cleaned seems to have solved headlights. Other lights remain issue.

Alternator was tested by shop as good. Removed headlight switch, all contacts look good, cleaned it up.

Still pulsing. So next up was the voltage regulator. Maybe the old cars do this, though?

Thanks for the advice on the ground. Feel safe starting the car now without frying anything!

-Rusty

 

[drm101]

Check all your grounds. The battery acts like a big capacitor and will help to smooth out the ripples that are generated in the vehicle by the alternator. Making sure the engine, body, frame, and battery are all connected on the ground side can help.

 

[neils63ss]

If this is an old style external voltage regulator the lights can dim/pulse. 6 or 8 cyl? What amp alternator are you running? Yes grounds are very important on these older cars.

 

[Rusty63]

Yeah, been checking the grounds. 8 cylinder and alternator voltage unknown (got it 10 years ago, new). It is an external voltage regulator. Here is the link to it:
https://www.autozone.com/batteries-starting-and-charging/voltage-regulator/duralast-voltage-regulator-vr715/130005_0_24874

Added another ground from cross member to alternator bracket.

Took some volt readings from the multimeter but misplaced the paper. Will find it tomorrow. The voltage went down and stayed down when the lights went on, that much I remember.

Was suggested to swap with a known-good alternator. Will try that, too.
Fried but back at it tomorrow.

-Rusty

 

[neils63ss]

Hi Rusty, What year nova is it I don't remember you saying Those old systems did dim at idle until you hit the gas at times. It depends what kind of after market accessories you have and the amps of the alternator. Did you think of upgrading to a 1 wire alternator? I own my 63 SS 40 years and know the cars well. I have other things you can check and questions. It's to much to write/understand with out the back and forth. I will pm you my phone #. I've helped others this way from the site. I find it much easier and don't mind helping. Oh and BTW the other terminal out to the side is for a noise capacitor I believe I will double check when you call I'll have the answer. Neil

 

[Custom Jim]

I looked up a diagram for a 63 and it shows a ground wire from the external regulator to the case of the alternator but who knows with the replacement if it's needed any longer. With your issue, maybe add a ground as it will not hurt anything.

On my 68, the external regulator is mounted to the rubber isolators and the hole on the side of the base of the regulator is for attaching a filter capacitor as well as one end of a short ground wire that the other end bolts to the backside of the radiator support.

I've not dug deep into this but I think the isolators are for reducing vibration into the regulator. Inside are parts that maybe GM figured out did not live long due to vibrations and the rubber isolators were a way to make the part live longer. Just a guess here just like MSD had rubber isolator standoff of some of their ignition boxes.

I also wonder if on mine the reason for a ground wire off of the regulator base to the radiator support was only there is the car had a factory radio and the filter capacitor bolted to the base of the regulator. Again a guess but when I have a chance I may look at the AIM and see if they call out anything different on wiring whether it had a radio or not. I looked at my wiring diagram and there is no ground wire called out between the regulator and the radiator support.

On your setup, maybe try raising the idle just a tad to see if this helps the low rpm pulsing. Alternators vary the output and this is due to the rpm it is spinning and what the regulator is sensing. If at too slow of an alternator rpm, the alternator even though it may be capable of 14V and let's say 37A of output,the low rpm limits this output. Just because an alternator is spinning does not mean it can put out it's rated power.

Also look at wire and fusible link connections. I have seen connections you have to look at real close as sometimes the fine strands break and a connection is only left with a strand or two to complete the circuit and this can play havoc with things.

Jim

 

[neils63ss]

voltage regulator

Hi Rusty that side terminal is for a radio frequency capacitor I f you google it you will see the picture of it and how it goes. Do no use the side terminal as a ground it is for the capacitor.

 

[Mike Goble]

The ground wire directly from the case of the alternator to the case of the voltage regulator assures that the ground for the reference is the same as the ground for the controlled element. When your alternator is working the case is the main ground for the entire electrical system. All current that leaves the alternator returns through the case.

 

[Custom Jim]

Hi Rusty that side terminal is for a radio frequency capacitor If you google it you will see the picture of it and how it goes. Do no use the side terminal as a ground it is for the capacitor.

On my 68, and different years may be done other ways, and would love to hear your input on this but I have a dedicated ground wire under the same screw that holds the clamp bracket for the capacitor to the regulators base and the other end of this ground wire goes under the bolt on the radiator support that also has the ground wire for the driver's headlight. Mine is also on the rubber isolators.

This is when I was working on my external regulator and the capacitor as well as the ground wire was not attached to the base of the regulator.

And then put back together:

If the case of the regulator is not to be grounded then how would the capacitor become grounded and work without this dedicated ground and the regulator mounted on rubber isolators ?. Circuits have to be completed and an ungrounded capacitor to me does nothing.

Also too on an original 68 regulator, on the underside there is a wire wrapped resistor with one tab connected to the base of the regulator.

I just don't know what this resistor does and how it would affect things if the original regulator bottom case was not grounded however maybe things changed with the circuit layout on the solid state ones ?

Bottom of an original 68 regulator:

And the one end of the wire wrapped resistor attached to the regulators stamped steel base and the tab that the capacitor connects to:

Like I said before I have not dug into how the regulator works and requires as far as wiring but I know when I did voltage tests on mine and adjusted the regulator I have not had any flickering of the headlights, dash lights and the readings on my Fluke meter seemed pretty stable with very little variance.

Some of my test results that might be useful to someone seeing how their results are:

Sadly I have no info on the solid state regulators as I'm wanting to keep my 68 how it was originally.

Jim

 

[Rusty63]

Custom Jim, that picture with "Screw Hole" was perfect! That is what my dad was using on his '66 for to mount the ground wire and then use to bolt on the horn relay as the attachment point to the radiator core support (which is what I did, too). However, he also screwed in his condenser to that same bolt on the horn relay. I will show him this photo and he can fix it. However, the local hot rod shop guy said you no longer need the condenser or a ground wire.

Mike, do you suggest then a ground from the regulator to the alternator?

Here are some readings from the battery, not sure if they are helpful.

Battery at rest: 12.39 V
Key On: 12.34 V
Key On, Car Running: 13.64 V
Key On, Car Running, Headlights On: 13.37 -13.44 V (fluctuates)

The local battery guru said that, whenever the accessories are turned on, the voltage regulator prevents any change in voltage, that is it's job; therefore, I should turn on the car, turn on these accessories and my in-car volt meter reading should not change. Well, it does, as you can see by the measurements: goes down and stays down.

As mentioned, maybe I am making a big deal out of this and the lights should be dim at idle on this old car. Just making sure. Thanks for all the replies!

-Rusty

 

[Mike Goble]

Mike, do you suggest then a ground from the regulator to the alternator?

Yes, for the reasons I explained above.