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| Normal Operating Voltage on a Stock Mechanical VR https://slantsix.org/forum/viewtopic.php?t=68769 |
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| Author: | Rodrju [ Sun Sep 27, 2026 7:38 am ] |
| Post subject: | Normal Operating Voltage on a Stock Mechanical VR |
Hello: Recently put on of those cheap cigarette light USB chargers that includes a digital voltmeter on the 68 Barracuda. Noticed that while at speed (40-60MPH) I am getting consistent 15-15.3 volts. At a stop light it dives all the way to 12.5. Car has what looks like the original round back alternator and mechanical Voltage Regulator. The 15 volts seems high. Is this normal for the mechanical regulator or is it time for it to be replaced? I was going to start by finding a NOS mechanical regulator and see if that makes a difference. Any other suggestions? Thanks. |
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| Author: | Charrlie_S [ Sun Sep 27, 2026 5:43 pm ] |
| Post subject: | Re: Normal Operating Voltage on a Stock Mechanical VR |
15 volts is too high. I usually shoot for 13.6 to 13.8 at road speed. Not really the proper way to read/set it, but it is in the ball park. Before replaceing the regulator, check all the conections in the field circuit. high resistance can cause excessivly high carging voltage. |
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| Author: | Greg Ondayko [ Thu Oct 01, 2026 7:31 am ] |
| Post subject: | Re: Normal Operating Voltage on a Stock Mechanical VR |
Justin, is your '68 all stock in the electrical department? I have found that sometimes the soldered wires to the diodes in the back of the alt become cracked and provide lots of voltage, except when at a stoplight. I re-didoed' my round-back alternator and soldered in new wires, and it worked correctly again. Dan also recommends an adjustable regulator for those mechanical / roundback cars if you are keeping things stock. I will see if I can dig up the post. I had a bunch of problems with my '69, and it is all stock in the electrics dept. Greg |
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| Author: | SlantSixDan [ Thu Oct 01, 2026 2:41 pm ] |
| Post subject: | Re: Normal Operating Voltage on a Stock Mechanical VR |
The factory '66-'69 heavy-duty adjustable mechanical regulator (Chrysler 2444 980, Echlin VR-35) can be had at a variety of prices. There's this adjustable version of the Standard VR-128/Echlin VR-1001 electronic regulator for the pre-'70 "single field" system. Bolt-on/plug-in, quite affordable. Beyond that, I know nothing about it. |
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| Author: | Greg Ondayko [ Thu Oct 01, 2026 5:36 pm ] |
| Post subject: | Re: Normal Operating Voltage on a Stock Mechanical VR |
Dan's can be had link is what I was referring to. Greg |
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| Author: | Rodrju [ Thu Oct 01, 2026 7:11 pm ] |
| Post subject: | Re: Normal Operating Voltage on a Stock Mechanical VR |
Dan and Greg The 68 is completely stock in the electric department. I feel strongly the alt and VR are original. I did manage to find a very old stock (1970s vintage) Standard VR-101 regulator that I intent to put on this weekend and see if it does a better job managing the voltage. Otherwise Ill grab an adjustable one. Updates to follow… Thanks! |
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| Author: | SlantSixDan [ Thu Oct 01, 2026 9:34 pm ] |
| Post subject: | Re: Normal Operating Voltage on a Stock Mechanical VR |
Be sure and run a ground wire from the alternator housing to the voltage regulator base, and from there to the battery negative terminal. There's often a "GRD" hole on the back of the alternator. If you use it, use a short self-tapping screw (too long and it'll hit the rotor). If the new regulator behaves the same, pretty good odds you've got excessive voltage drop across the ignition switch and through the firewall connectors, causing low voltage at the "IGN" terminal of the regulator, making it crank up the line voltage until it sees normal voltage on the "IGN" terminal. Fix this by putting in a field-loads relay. Details on request. |
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