Hello, I just wanted to ask if there was any way to raise the minimum voltage level when the car is idling at say ~800 RPM with the Headlights on? It seems that My voltage regulator is good, ant not letting things go over ~14.7V when the car is Running down the road and puttering around town, but stopped / idling with headlights on tends to drop the voltage below 12V, say to ~11.8V.


Is this an alternator issue? if so Is there a way to resolve it without a complete alternator replacement?
I have generally no problem replacing all the bits in the Back of the Alt, as I have Diodes and Capacitors on hand for the Round back Alts. I can check for good fields in the stator and rotor as well, but have yet to do that.

I have checked all the Firewall bulkhead connections And they are good, but have yet to run a extra / Second Charging wire from the alternator Battery post to bypass the Dash Mounted Alternator Gauge.

This is on my '69 Dart. with the stock round back alternator and the Stock Mechanical points type Voltage Regulator.

Thanks Sages!

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Mostly an alternator issue. Despite all the hullabaloo in '60 about how the alternator keeps charging even at idle, while they were better than the previous DC generator, most variants of the Chrysler alternators were weak at low RPM, clear all the way up through about 1980 or so when the alternators were redesigned for increased field current, and even then, they were not as good at low RPM as (for example) the GM Delco alternators or the '89-up Chrysler, Bosch, and Nippondenso 40/90 units.

And that gets a lot worse with "remanufactured" alternators thrown together with mismatched rotors, stators, and pulleys.

But your voltage regulator isn't doing you any favours, either. ~14.7v is too high unless it is very, very cold outside and your battery is rather heavily discharged.

What to do about all this depends on how much effort and expense you want to go to.

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Too many people who were born on third base actually believe they've hit a triple.

If you want to keep the alternator "stock" appearing, It might be possible for a "GOOD" alternator shop the "build" you a higher output alternator. Two other solutions. Put a smaller pully on the alternator. That will speed it up compared to engine rpm. Or just change to a much later Chrysler or Nippondenso alternator. Also, as Dan said I would cut back on your charging voltage. The factory service manual will tell you how to adjust that mechanical regulator.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thanks for the insights Charrlie and Dan,

I will look into this a bit further when I get time.

On this vehicle, I do want a stock look for the engine bay, so I would rather avoid smaller pulleys and Nippondenso Alternators.

I can check in on the Mechanical regulator output as well.

Greg

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Greg. I have a good alternator shop I use. He is going to look into up grading a round back alternator for higher idle output. He can do it if the parts are still available, but he is not sure they are.
I'll let you know.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I have A parts store (Mighty I think) round back alt on the '64 Grüne Hölle Dart that was on there when I received it back in 2015, It works great and I have no problems at idle with that one even when running Lights, elect fuel pump and elect fan, and O2 Sensor

I have upgraded things on that car and have Relays for everything except the headlights. Maybe I should pull that one off and see how it performs on my '69 dart as an apples-to-apples test.

Thanks, Charrlie

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I can dig not wanting to put on an alternator that looks different, but would it really bother you to have a pulley on the alternator 3/8" or 1/2" smaller in diameter than the one that's on there now‽ I don't mean those ugly aftermarket ones, I mean a legitimate Chrysler pulley, painted black as intended. Factory pulleys ranged from 2-1/2" to 3-1/4" diameter. What pulley the factory put on depended on the alternator and other factors like the car's axle ratio, and whether or not it had A/C.

As to the regulator, and a possible alternator upgrade: the usual way to make more output at idle is with a rotor wound so as to draw more field current, thus inducing greater current in the stator -> output. That's why those "100 AMP!!!!!!!" alternator upgrade kits (JC Witless, etc) tended to seriously degrade the low-RPM output of the alternators they were installed in: their big-wound stator could throw off more amps with high alternator (=engine) speed, but couldn't match the output of the stock stator at lower speeds.

Higher field current means a harder life for the voltage regulator; if you wish to stick with olde-tyme tech rather than putting in an electronic regulator, even one that looks not too different to the original, and you don't want the regular voltage regulator's points to weld themselves, you might wind up going to the heavy-duty regulator Chrysler used starting in '66 on cars with upgraded charging systems. From the factory, these were an externally-adjustable regulator, with a grommetted small screw. Factory part number 2444 980; Echlin VR-35. This one. Made by Essex Wire whether it came to the end user in a Chrysler box or an Echlin box. Hooks up the same as the light-duty regulator, but requires different mounting holes. I had one of these on my '65, and it worked quite well for many years.

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Too many people who were born on third base actually believe they've hit a triple.

I would certainly entertain the idea of the adjustable VR and A factory style pulley.
I was unaware of the different diameters from the factory.
I guess I was thinking of of racing catalog or generic parts store part.

I suppose I should measure the one that is on there now. How / where are they measured?

Where are other size oe pulleys sourced?

Thanks Sages!

Greg

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The pulley is measured across its diameter. The 2-1/2" single-groove pulley is part number 2444 478, and is a steel thing painted black.

At this late date, factory pulleys are sourced where you can get 'em! Time was, I'd've said eBay—I'm good at searching there, or at least I was; a year or two or five ago, I would have been able to get some good results. Now the search function is broken to the point of uselessness—hundreds of irrelevant results because the algorithms and "artificial intelligence" override your search string, plus a bunch of "sponsored" results (i.e., spam), plus sellers including a bunch of bogus keywords in their auctions (which now go through an "artificial intelligence" "listing assistant", so who's actually larding them up with the bogus keywords?). Even a detailed search string with constraints returns fenders for '47 Buicks, box fans, mason jar lids, action figures, stuffed animals, everything except what you're after.

The flat-out unavailability of so many parts, or only in gross-approximate/low-quality form, would drive me out of my skull if I hadn't retired from old-car ownership.

Oh, since we're on the topic: pay careful attention to the rest of your charging system/circuit if you go upgrading your alternator.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Pulley measured for the diameter at the front or rear outer edge? Not in the valley where the bottom of the v belt rides?

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Correct. Across the outer edges.

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Too many people who were born on third base actually believe they've hit a triple.

Got it thanks!

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Why are you worried about low voltage at idle?

My 68 had the original 25 A alt and it always pulled the voltage down but I never had trouble with that. That's why you have a battery! It stores lots of energy to run things, and you never have to sit at low idle for an hour with it discharging just a little bit.

Lou

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Home of Slant6-powered fun machines since 1988

Everything gets very dim when the voltage is that low. and with all the glaring seemingly non-focused beam patterns on modern cars of the last ~5 years, I want all the help I can get. I know I don't idle a lot but it does bother me. I feel it should be slightly higher.

I need to go through and thoroughly check everything on this car anyway. One of the wiper speeds did not work on my Kentucky trip too. I think that is a switch issue.

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Everything works less/worse at lower voltage. Not just lights, but ignition (esp. electronic), blower, wipers, etc.
The lowest-rated alternator factory-installed in '68 was a 37-amp item. The lowest-rated alternator factory-installed on an A-body was a 30A unit starting in '62.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.