1968 How to test Voltage Regulator?

[Bobsdad]

Hi everyone, been working on a problem w the charging system. Recently replaced the alternator and alternator harness as well as a new voltage regulator from Kentucky Mustang.
Alternator and battery both tested fine at Autozone.
After driving 20 minutes at neighborhood speeds, while idling in park, my multimeter showed battery voltage oscillating between 14.8 volts and 15.5 volts.

It looks to me like my new voltage regulator is bad, what do you think? Also, does anyone have info on how I can test the regulator to verify it's faulty?

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[speedy02]

Which Voltage Regulator did you buy off of Kentucky Mustang? Looking on their site I see they have a Scott Drake (C8TF-10316-1) unit and a AMK Product (C8AF-10316-A). If I remember correctly you have a 302 without A/C???

 

[Bobsdad]

Which Voltage Regulator did you buy off of Kentucky Mustang? Looking on their site I see they have a Scott Drake (C8TF-10316-1) unit and a AMK Product (C8AF-10316-A). If I remember correctly you have a 302 without A/C???

Yessir it's a C code but we believe a 302 was later put in.

I bought

https://www.kentuckymustang.com/eng...-c8af-10316-a-w-o-a-c-late-1968-1970-amk.html

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[speedy02]

I am attaching the Ignition Starting and Charging guide. Looks like there is a ground wire attached to the plate on the Regulator. Have you checked to make sure the ground is attached correctly?

 

[Bobsdad]

Thanks. I haven't checked the regulator ground, I'll see if I can identify which wire it is today

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[franklinair]

As a rule of thumb, I look for 13.5 volts measured on the Battery Posts with the car running @ idle RPM. Increasing RPM, the voltage should remain @ 13.5V. That's how I test the Voltage Regulator.
If you have to replace the Voltage Regulator I HIGHLY recommend a Solid State type. They are more efficient.
If you're concerned about original appearance, just swap out the blue V/R cover.

Neil

 

[Bobsdad]

As a rule of thumb, I look for 13.5 volts measured on the Battery Posts with the car running @ idle RPM. Increasing RPM, the voltage should remain @ 13.5V. That's how I test the Voltage Regulator.
If you have to replace the Voltage Regulator I HIGHLY recommend a Solid State type. They are more efficient.
If you're concerned about original appearance, just swap out the blue V/R cover.

Neil

Thanks, Neil!

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[Bobsdad]

I am attaching the Ignition Starting and Charging guide. Looks like there is a ground wire attached to the plate on the Regulator. Have you checked to make sure the ground is attached correctly?

I just used my multimeter and saw between 0.1 ohms and 0.6 ohms slowly ticking up and down. When reattaching the ground to the regulator I cleaned it up a bit with a wire brush.

Does this resistance reading sound acceptable?

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[franklinair]

Should be OK.

Neil

 

[Bobsdad]

Thank you, gentlemen! Sounds like Kentucky Mustang sent me a bad regulator... I'll be sending it back and getting a solid state regulator.

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[Bobsdad]

Hello everyone, things have improved but my problem isn't fixed and your suggestions would be hugely appreciated.
So I replaced the voltage regulator with another one from O'Reilly. It's a short one so I believe that guarantees it's solid state. Pre ignition battery voltage was 12.48 V. After a 20 minute drive at 25 mph, voltage this time was stable at 14.16 V.

I took it out on a country road and opened her up to 55mph for a couple minutes and when I was back in my neighborhood, at idling speed, it died.

The good news is it started back up without trouble and voltage was again stable at 14.06 V.

I'm guessing I have some other mystery electrical or fuel problem. Also, the alternator and power steering belts are new and are squealing loudly, and the power steering pulley wheel looks like it may be wobbling, is that normal? I can post a video.

Any help would be greatly appreciated.

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[Mosesatm]

Does it die only at idle? Is it idling too slow?
The belts squeal because they are loose.
The PS pump was fine and should not wobble. Might Andy have installed a different one?
Tighten the belt to see if the wobble stops.

 

[Bobsdad]

Does it die only at idle? Is it idling too slow?

The belts squeal because they are loose.

The PS pump was fine and should not wobble. Might Andy have installed a different one?

Tighten the belt to see if the wobble stops.

Thanks, Arlie! I'll re tighten the belts. Andy just reinstalled the PS I brought him and I didn't feel any wobble in the pulley when the engine was off.

It's only ever died in first gear around 15mph, like when I have my foot off the gas and I'm applying the brake to go around a corner. Two other times it was when I was at a stop sign and the instant I applied pressure to the gas it died. I'm suspecting that maybe the idle needs to be raised, perhaps due to the change in elevation between WA and IL?

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[Mosesatm]

The car ran so well for me I didn’t touch any of the adjustments. I think idle is supposed to be 650 with the car in gear. Does the carb have a dashpot?

 

[Bobsdad]

The car ran so well for me I didn’t touch any of the adjustments. I think idle is supposed to be 650 with the car in gear. Does the carb have a dashpot?

Yessir, looks like I'll try making an adjustment there before searching for a vacuum leak. It looks like perhaps the 1200 ft difference in elevation may have exacerbated my issue.

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[Mosesatm]

Does it work properly?

 

[Bobsdad]

Does it work properly?

Unfortunately work travel has been in the way, hopefully I'll be able to check this week. Before adjusting the dashpot I think I'm going to adjust the air / fuel mixture screws since I never did that.

I'm currently looking for a good article explaining how to adjust a dashpot on an Autolite 2100 carburetor.

Arlie, any chance you remember if when you installed the brake booster did you use a vacuum hose or stiffer hose like a power steering hose?

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[Mosesatm]

Unfortunately work travel has been in the way, hopefully I'll be able to check this week. Before adjusting the dashpot I think I'm going to adjust the air / fuel mixture screws since I never did that.

I'm currently looking for a good article explaining how to adjust a dashpot on an Autolite 2100 carburetor.

Arlie, any chance you remember if when you installed the brake booster did you use a vacuum hose or stiffer hose like a power steering hose?

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It was a stiff hose but Andy rerouted it so I’m not sure what’s there now.

 

[Bobsdad]

Good news! I retuned the air fuel mixture and fixed a small leak in the carburetor and it ran nicely this weekend. Even took it to my first show! I was surprised that some folks were a bit familiar with the GT/CS but nobody I met had ever seen one in person before.

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[Mosesatm]

Definitely a sharp looking car. Is that a custom license plate?