GM 1 WIRE alternator

[marko]

Have a 1950 F1( flathead). converted to 12 volts. was thinking about going with a GM one wire alternator. I'm not running a radio, AC, heater, ext... just lights. Where can I find one of the one wire GM alternators?.. and.. what about mounting brackets.. is that going to be a issue?.. thanks a bunch.. Marko.

[51 MERC-CT]

Just about any auto parts supply store will have or can get one.
There are various mounting brackets available from speed part/hot rod part suppliers

[cas3]

speedway is about the easiest, but then they take over your computer for several months

[Art Newland]

I bought one of these, but haven't used it yet.
https://www.dbelectrical.com/product...wide-belt.html

[JSeery]

I have read claims that the newer one-wire generators work better than the ones from the past. But the three-wires are easy enough to wire up I would sure consider that option. Also easier to service on the road if a problem ever occurred.

[19Fordy]

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When I installed my GM 1 wire alternator on my Ford flathead I also installed a fusible link in the wire that runs between the + side of the solenoid and the alternator.

[flatheadmurre]

I usually use the real early low power 10SI ones and just hook them up to the voltage regulator as connection point that way the amp meter function as it should in the vehicle.
The 10SI is easy to work with and i can turn it into POS GRD with just changing the rectifier if needed for 6V.

[Bob/Pa]

Marco, sent you a private message.

[51504bat]

I bought the single wire GM alternator and bracket for the 8ba in my '39 p/u from Quality Power in Yucaipa, CA. but they are available almost everywhere.

https://www.qualitypowerauto.com/catalog.php?item=8

They are available in both 6 and 12 volt and positive and negative ground.

[Annixter]

As with others, I'd go with a 10SI case one-wire. One-wires have been around a long time, and you should be able to find one almost as easily as a three-wire if you're on the road and break down--especially if your system is good with a 63amp. Worse case, keep a spare for long trips.

One-wire is a much cleaner setup than a three-wire. A lot of people will tell you to tap into the ignition feed going to the coil for the cleanest routing, but it's not correct practice. The ignition terminal post on the switch should be dedicated to the ignition system only. Tapping into it for other circuits is a headache waiting to happen due to overloading the switch contacts and introducing unnecessary problems with your ignition supply. For a three-wire setup, you'll want to bring a dedicated wire from the accessory post on the switch or tap into an accessory circuit that can handle the additional load.

While discussing what amperage alternator your ignition system needs is a whole other conversation that requires you add up all the continuous and intermittent loads and calculate in certain load factors, my advice is to (1) do the math rather than assuming and (2) don't skimp on the charging wire gauge since the engine compartment heat exacerbates voltage drop. In the case of your battery cables and charging cable, bigger is better. You'll see all sorts of people running all sorts of amp alternators, and when you ask them how they came to that amperage, they'll tell you, "my buddy told me," "a forum post told me," "I looked at a factory setup," "some generic chart told me," "some salesman told me." Most people don't calculate the actual amperage their system draws (and add in certain load factors) and, therefore, likely run alternators with either too low of amperage or unnecessarily too high. The largest culprits of designing undercharging systems were the auto manufacturers, so I warn against assuming a 63amp is adequate.

If you're running a very bare bones setup as you suggest (no heater, radio, etc.), you're likely okay at 63amps, but you should do the math to know for sure. Also, now's the time to plan for adding a heater, radio, wiper motor, front turn signals, etc. The difference between a 63amp alternator and #8 charging wire and a 100amp alternator and #4 charging cable is around $30 versus spending a another $100 down the road to upgrade--not including having to do the labor and rewire. If you want help sizing your alternator, shoot me a PM and I'll send you an excellent thread link.

[lefty rodan]

Hi:
Please send me the link to properly sizing my alternator. Thanks for your effort.


lefty Rodan [email protected]

[Ross F-1]

It shocks me how many people are putting 100+ amp 10Si's on vehicles that got by with a 30 amp generator. I don't get it. These are mostly stock vehicles, too. More is not always better.

[estout81]

Ross F-1
I agree! What is the fascination with GM parts on a Ford anyway? My avatar does just fine with a Ford generator. No alternator.

[Annixter]

Originally Posted by Ross F-1

It shocks me how many people are putting 100+ amp 10Si's on vehicles that got by with a 30 amp generator. I don't get it. These are mostly stock vehicles, too. More is not always better.

Factories notoriously undersized their charging systems to save money. The savings from less feet of copper in the generator/alternator and in wire gauge adds up quickly. So long as the battery, motors, and alternator/generator lasted long enough to not fail under warranty or within a year range to warrant a recall, more money for the manufacturers.

Case in point, when designing the wiring harness and charging system for my '53 F100, I started by modeling the system off my father's bone-stock, plane-Jane 1973 Chevy C10 pickup (No a/c or power windows). After adding up the continuous loads, the intermittent loads, and then after adding the proper load factors to the continuous load sum, that plane-Jane Chevy was drawing 82amps on the continuous side and had another 40amps of potential intermittent load available. Yet the factory gave it a 63amp alternator. Could it physically run on that 63amp alternator? Sure. . . most of the time. Was it commonly undercharging during certain times. Definitely. Was the undercharging putting unnecessary strain and wear on the battery, alternator, and motors. Yep.

The people you blanket-criticize might have calculated the actual amps their system draws and are running the proper-sized alternator to ensure their system is never undercharging rather than assuming the factory didn't skimp. I'm sure some of them don't know better and simply chose a random amp, too, but to assume they are all somehow incorrect isn't objective. I could have assumed that since my father's '73 Chevy pickup ran a 63amp alternator from the factory, my '53 with nearly the exact same components would also need a 63amp. Instead, I did the math and designed the system using a proper 90 amp alternator for that system. Maybe you would scoff at that, but math and physics in this case don't lie.

[51504bat]

This link has an amp load calculator chart.

https://www.qualitypowerauto.com/pag...Calculator.php

[Annixter]

Generic calculators like that one are very inaccurate. What, exactly, is included in a "normal" vehicle or a "custom" vehicle, and what are the amp ratings for those components? The generic calculators use averages. They may assume an 8amp heater blower motor when yours draws 12, or they assume four turn signals when you have two. Add up these deviations and it's the difference between a 63amp and an 80amp alternator.



While it takes time and energy, to properly choose an alternator's amperage one needs to measure the system by adding up the actual amp ratings for each bulb, motor, etc.--preferably from the actual parts' tags or spec sheet--and then do some load factor additions for a buffer.



The electrical system of a car is just as important and potentially dangerous as the drivetrain, and I wouldn't guess if my driveshaft pinion angle is within tolerance. I'd get out an angle finder, paper and pen, and get under the car.

[G.M.]

Originally Posted by marko

Have a 1950 F1( flathead). converted to 12 volts. was thinking about going with a GM one wire alternator. I'm not running a radio, AC, heater, ext... just lights. Where can I find one of the one wire GM alternators?.. and.. what about mounting brackets.. is that going to be a issue?.. thanks a bunch.. Marko.

I have two GM one wire alternators that I have had for about 25
years and still work good. I don't know about 12 volts, mine have
been converted to 6 volts. The motor shop that does my work
suggested they install 28 volt stators so they would charge higher
at idle and low RPM's with a large diameter pulley. They really work
good. Chestnut Hill electric motor shop in Denver, Pa. Did the work.
G.M.

[39portlander]

Marko, why not a Ford one wire? Either way in your wiring you can never have too many grounds.

[marko]

where would I find one of those? can I keep my same bracket?... interesting.

[flatheadmurre]

Where are you located ?
Shouldn´t be much of a problem to get hold of a bracket and 1-wire 10SI if you´re not living in Russia or something like that...