The Ford Barn

fredM · 03-29-2026, 01:27 PM

I was checking out my voltage regulator because I have Sunday off and I'm spending it with my Mercury. The amps gauge has a kind of a flicker to it and while trying to find out why I noticed that with the cover off the amps gauge works great. When I put the cover on the volts drops almost a half volt. Through trial and error, I know that the cover is not hitting anything. I went as far as putting a double gasket on to rule out anything simple. So, I put a plastic bowl on it and went for a ride. All is well but I don't want to have a bowl on the regulator. Is there any magnetic field I'm upsetting? Something else? Thanks.

JayChicago · 03-29-2026, 01:45 PM

Just a guess:
The base of the voltage regulator needs good ground contact to the firewall. Are your cover attaching screws raising the base so it loses some of its ground contact? But you said you already looked for this kind of interference.

ford38v8 · 03-29-2026, 01:52 PM

The cover is essential in maintaining a steady operating temperature within the regulator. To this end, any adjustments must be followed up with replacing the cover, to return to operating temperature condition, then check results of the adjustment.

petehoovie · 03-29-2026, 02:23 PM

Quote:

Originally Posted by fredM

I was checking out my voltage regulator because I have Sunday off and I'm spending it with my Mercury. The amps gauge has a kind of a flicker to it and while trying to find out why I noticed that with the cover off the amps gauge works great. When I put the cover on the volts drops almost a half volt. Through trial and error, I know that the cover is not hitting anything. I went as far as putting a double gasket on to rule out anything simple. So, I put a plastic bowl on it and went for a ride. All is well but I don't want to have a bowl on the regulator. Is there any magnetic field I'm upsetting? Something else? Thanks.

mfirth · 03-29-2026, 02:41 PM

Interesting as I had a Leece Neville voltage regulator on a boat that did the same thing.A marine mechanic friend couldn't figure it out either. Lid on it would discharge, lid off worked fine. Luckily, I found a plastic butter container that fit perfectly. I did replace it a new one but kept it for a spare. Electricity is funny stuff....

hueyhoolihan · 03-29-2026, 05:40 PM

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i would suspect a faulty regulator, and buy a new one and determine if i got the same results or not.

fredM · 03-30-2026, 02:56 AM

I learned yesterday that, yes, temperature is the boss when it comes to the regulator. Off went the plastic bowl, and on went the original cover. Thanks everyone.

Terry,OH · 03-30-2026, 06:34 AM

Modify the settings so the regulator, with the cover on, gives the proper output.

rotorwrench · 03-30-2026, 11:47 AM

All three poles are electromagnetic in function. One is just a cutout. The others control current and voltage. Most covers are ferrous steel which can be magnetized over time. Put a compass or a thin strip of steel next to it to see if it either reacts the compass or attracts the steel piece. The steel cover affects the poles but the affects should be very close to negligible. The voltage output should be around 7.2 + just a bit if properly adjusted. The current limiter is there just to keep it in check. Max output is around 35-amps but it takes special equipment to adjust a VR properly.

koates · 04-02-2026, 07:29 PM

It is very normal for the voltage setting to change slightly when the metal (steel) cover is fitted on to the regulator. You have to set the voltage high enough to compensate for the steel covers magnetic effect change. Some regs had aluminium or plastic covers to prevent this effect. I have repaired many hundreds of voltage regulators in past years when they were on almost every vehicle. Regards, Kevin.

51shoeboxer · 04-03-2026, 11:56 AM

Quote:

Originally Posted by fredM

I learned yesterday that, yes, temperature is the boss when it comes to the regulator. Off went the plastic bowl, and on went the original cover. Thanks everyone.

Diagnosis by replacement is never a good policy.

fredM · 04-05-2026, 06:49 AM

A couple of days ago I found this Borg Warner regulator in my basement. These pictures will show that it has screw adjustments and that excited me so I mounted it right up. I got in the Mercury and put the key in, hit the button and when it started the amps gauge did not flutter one little bit. took the cover off to adjust for 7 1/2 volts with cover on. The nightmare is over. Never learned so much. One more thing. Does the capacitor attach to FLD as I have done? I have always done it that way. My car is a radio delete.

hueyhoolihan · 04-05-2026, 09:49 AM

a steady diet of bitter frustration, can enhance the sweetness of success... congratulations!

petehoovie · 04-05-2026, 02:01 PM

Quote:

Originally Posted by fredM

A couple of days ago I found this Borg Warner regulator in my basement. These pictures will show that it has screw adjustments and that excited me so I mounted it right up. I got in the Mercury and put the key in, hit the button and when it started the amps gauge did not flutter one little bit. took the cover off to adjust for 7 1/2 volts with cover on. The nightmare is over. Never learned so much. One more thing. Does the capacitor attach to FLD as I have done? I have always done it that way. My car is a radio delete.

51shoeboxer · 04-05-2026, 02:14 PM

Quote:

Originally Posted by hueyhoolihan

i would suspect a faulty regulator, and buy a new one and determine if i got the same results or not.

Diagnosis by replacement is never a good policy.

Don T · 04-05-2026, 02:19 PM

So do we set the regulator higher or lower than the target 7.2 when the cover is off?

rotorwrench · 04-05-2026, 05:08 PM

The capacitor was generally just for radio noise from the buzz of the regulator points vibrating open and closed. It shouldn't hurt anything being on there though. It might keep the points clean longer. Some had a cap on the generator as well. Another place was on the fuel quantity transmitter. Ford had a noise suppression kit back in the day for radios that were sensitive to RF noise. It came with an instruction sheet.

alchemy · 04-05-2026, 05:10 PM

Got a part number on that Borg Warner regulator? Would be so much nicer to adjust with a screw rather than bending tabs.

koates · 04-05-2026, 10:19 PM

The capacitor should be on the armature terminal and not on the field terminal. I always aim for 7.5 volts rather than 7.2 volts . Set the voltage at about 7.7 volts and then fit the steel cover and see what you get. A bit of trial and error is involved here. Regards, Kevin.

fredM · 04-06-2026, 06:40 AM

I think the regulator number is R-141. When I look that up nothing comes up. The only information on the regulator body is made in USA and positive ground. Similar Borg Warner units are priced higher on e-bay. Too bad that the original unit flutters a bit. All 3 of my spares flutter but work well. They are all used but nice appearing so who knows what other owners, owner's kinfolks, or their paperboys have done with them.

03-29-2026, 01:45 PM	#2
JayChicago Senior Member Join Date: Jan 2019 Location: Chicago Posts: 1,028	Re: Voltage regulator Just a guess: The base of the voltage regulator needs good ground contact to the firewall. Are your cover attaching screws raising the base so it loses some of its ground contact? But you said you already looked for this kind of interference.

03-29-2026, 01:52 PM	#3
ford38v8 Senior Member Join Date: Jul 2011 Location: SF Bay Area Posts: 7,634	Re: Voltage regulator The cover is essential in maintaining a steady operating temperature within the regulator. To this end, any adjustments must be followed up with replacing the cover, to return to operating temperature condition, then check results of the adjustment. __________________ Alan

03-29-2026, 02:41 PM	#5
mfirth Senior Member Join Date: Aug 2017 Location: ohio Posts: 1,165	Re: Voltage regulator Interesting as I had a Leece Neville voltage regulator on a boat that did the same thing.A marine mechanic friend couldn't figure it out either. Lid on it would discharge, lid off worked fine. Luckily, I found a plastic butter container that fit perfectly. I did replace it a new one but kept it for a spare. Electricity is funny stuff....

03-29-2026, 05:40 PM	#6
hueyhoolihan Senior Member Join Date: Dec 2024 Location: central coast california Posts: 593	Re: Voltage regulator Sponsored Links (Register now to hide all advertisements) i would suspect a faulty regulator, and buy a new one and determine if i got the same results or not.

03-30-2026, 02:56 AM	#7
fredM Member Join Date: Apr 2025 Posts: 58	Re: Voltage regulator I learned yesterday that, yes, temperature is the boss when it comes to the regulator. Off went the plastic bowl, and on went the original cover. Thanks everyone.

03-30-2026, 06:34 AM	#8
Terry,OH Senior Member Join Date: May 2010 Posts: 5,394	Re: Voltage regulator Modify the settings so the regulator, with the cover on, gives the proper output.

03-30-2026, 11:47 AM	#9
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,006	Re: Voltage regulator All three poles are electromagnetic in function. One is just a cutout. The others control current and voltage. Most covers are ferrous steel which can be magnetized over time. Put a compass or a thin strip of steel next to it to see if it either reacts the compass or attracts the steel piece. The steel cover affects the poles but the affects should be very close to negligible. The voltage output should be around 7.2 + just a bit if properly adjusted. The current limiter is there just to keep it in check. Max output is around 35-amps but it takes special equipment to adjust a VR properly.

04-02-2026, 07:29 PM	#10
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,218	Re: Voltage regulator It is very normal for the voltage setting to change slightly when the metal (steel) cover is fitted on to the regulator. You have to set the voltage high enough to compensate for the steel covers magnetic effect change. Some regs had aluminium or plastic covers to prevent this effect. I have repaired many hundreds of voltage regulators in past years when they were on almost every vehicle. Regards, Kevin.

04-05-2026, 09:49 AM	#13
hueyhoolihan Senior Member Join Date: Dec 2024 Location: central coast california Posts: 593	Re: Voltage regulator a steady diet of bitter frustration, can enhance the sweetness of success... congratulations!

04-05-2026, 02:19 PM	#16
Don T Senior Member Join Date: Mar 2017 Location: Alberta Canada Posts: 108	Re: Voltage regulator So do we set the regulator higher or lower than the target 7.2 when the cover is off?

04-05-2026, 05:08 PM	#17
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,006	Re: Voltage regulator The capacitor was generally just for radio noise from the buzz of the regulator points vibrating open and closed. It shouldn't hurt anything being on there though. It might keep the points clean longer. Some had a cap on the generator as well. Another place was on the fuel quantity transmitter. Ford had a noise suppression kit back in the day for radios that were sensitive to RF noise. It came with an instruction sheet.

04-05-2026, 05:10 PM	#18
alchemy Senior Member Join Date: May 2010 Location: middle of Iowa Posts: 1,001	Re: Voltage regulator Got a part number on that Borg Warner regulator? Would be so much nicer to adjust with a screw rather than bending tabs.

04-05-2026, 10:19 PM	#19
koates Senior Member Join Date: May 2010 Location: Melbourne Australia. Posts: 2,218	Re: Voltage regulator The capacitor should be on the armature terminal and not on the field terminal. I always aim for 7.5 volts rather than 7.2 volts . Set the voltage at about 7.7 volts and then fit the steel cover and see what you get. A bit of trial and error is involved here. Regards, Kevin.

04-06-2026, 06:40 AM	#20
fredM Member Join Date: Apr 2025 Posts: 58	Re: Voltage regulator I think the regulator number is R-141. When I look that up nothing comes up. The only information on the regulator body is made in USA and positive ground. Similar Borg Warner units are priced higher on e-bay. Too bad that the original unit flutters a bit. All 3 of my spares flutter but work well. They are all used but nice appearing so who knows what other owners, owner's kinfolks, or their paperboys have done with them.