I think it's time to move to an alternator

[Cool Hand Lurker]

I have heard that a variable resistor that can be adjusted from inside the car can replace the 3rd brush system. Can anybody give me more info?

[Herb Concord Ca]

Thanks Nkaminar, for the answer to my question above.

[J Franklin]

If the generator can put out 15 amps I wouldn't worry about it. Mine will at least peg my ammeter at 20.

[cokefirst]

I agree that a modern Generator does not look good on the A. I put a power gen alternator on mine. 6 volt, positive ground and it looks like the Model A generator. Anyone familiar with the Model A can tell the difference but I am not showing my car so it makes no difference. I put in Halogen bulbs since I could not see the lights on my A when I had them on at night. The Halogens work as good as modern sealed beams but I was also running negative charge with the set up. I LOVE my power gen. I like the original look and the quick return to center on the Ammeter when after starting the engine.

[Bob Bidonde]

It isn't safe to drive a stock Model "A" in modern traffic.

[Badpuppy]

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Originally Posted by spinelll

Thank you for all of the replies.
I guess my main question is whether the stats listed in the attached image are abnormal for a generator in good shape. If they are abnormal, then what would the numbers be with a "good" generator?
Leo

Idle readings are normal because the cutout doesn't cut in until higher revs.

10 A at high speed indicates FSB 11/29 hasn't been applied, and it includes coil current as well as battery charge current. Battery charge by itself should be no more than 1-2 amps.

The ammeter indicates battery charge, not generator output.

[Jim M]

A couple of years ago I had the same decision to make. Wanting to keep the old girl as stock as possible I was fortunate that my local club suggested a guy who rebuilds generators and alternators. I took my generator to him and a week later it was ready. Looked like it just came out of a new box. I put it on and did absolutely NOTHING but put it back on the car and hooked up the wires. It worked fabulous and I have real bright lights at night. Glad I went that route. Happy and Healthy New Year to all😊👍.

[WHN]

Originally Posted by Bob Bidonde

It isn't safe to drive a stock Model "A" in modern traffic.

Could you elaborate on this?

Interesting advice being given here.

[J Franklin]

Originally Posted by Bob Bidonde

It isn't safe to drive a stock Model "A" in modern traffic.

Technically it isn't safe driving anything in modern traffic with modern drivers.

[AL in NY]

Bob Bidonde, No it's not if you're puttering along at 40 mph..........

[J Franklin]

When I lived in Los Angeles I usually drove my A on the freeways because there were multiple lanes so I didn't hold up any traffic and usually it moved slower than many surface streets. Nobody on the freeway ever rushed a left turn across my path either.

[spinelll]

Originally Posted by Badpuppy

.

10 A at high speed indicates FSB 11/29 hasn't been applied, and it includes coil current as well as battery charge current. Battery charge by itself should be no more than 1-2 amps.

The ammeter indicates battery charge, not generator output.

Badpuppy

What's FSB 11/29? Ford Service Bulletin? What do you mean by hasn't been applied?

Thanks
Leo

[DHZIEMAN]

Rebuilding the good ole Model A generator is the way to go if you wish to remain original. Some folks are not aware that Henry sized the generator to deal with battery needs for times the car was built and sold. And there are adjustments that can be made with the 3rd brush. This old gen can crank out a bit more than 10 amps. The trick in adjusting is the average current draw, day and night that varies by how the car is driven. Lots of night driving, up the charge rate. No night driving, lower charge rate. Overcharging is as bad as undercharging. An Alternator will solve all that automatically but......

[Badpuppy]

Originally Posted by spinelll

Badpuppy

What's FSB 11/29? Ford Service Bulletin? What do you mean by hasn't been applied?

Thanks
Leo

FSB 11/29 simply moves the ignition coil wire from the battery side of the ammeter to the generator side, at the firewall junction box. The ammeter then reads only current to/from the battery; the coil is out of the circuit.

At 6 volts the coil draws about 4 amps. Revving the engine increases voltage, so the coil draws more, and you saw 10A overall.

[katy]

Originally Posted by Badpuppy

At 6 volts the coil draws about 4 amps.

That's on a non-running engine, a running engine will draw less due the time between when the points are closed and when they are open.

[eric12alexander]

Running a 6v generator hope I’m not gonna regret converting to 12v

[Badpuppy]

Originally Posted by katy

That's on a non-running engine, a running engine will draw less due the time between when the points are closed and when they are open.

True, it's called modulation - dwell time vs total time between cylinders; multiply that fraction by the 6V steady current draw.

But, KISS.

[Badpuppy]

Originally Posted by eric12alexander

Running a 6v generator hope I’m not gonna regret converting to 12v

Only regrets should be trouble and expense of replacing battery, bulbs, cutout, coil, and field windings. To say nothing of dealing with horn and wiper motors. Switch to negative ground while you're at it to be compatible with modern stuff. When done, you've doubled the power output of the generator - not that you need it, although 50 CP headlights are a strain at 6V.

[rotorwrench]

Originally Posted by Badpuppy

FSB 11/29 simply moves the ignition coil wire from the battery side of the ammeter to the generator side, at the firewall junction box. The ammeter then reads only current to/from the battery; the coil is out of the circuit.

I'm sure this was done to put all loads on the ammeter charge side so that it would register a discharge that way. Wired the other way it was on the discharge side so the indication didn't reflect a discharge. It either case the power wire to the coil was still electrically connected but was not giving correct indications on the ammeter the previous way.

The ammeter only reflects which way the current is flowing. It's either flowing from the generator or it's flowing from the battery depending on whether the generator is working or not.

[ALJ]

Originally Posted by nkaminar

I am very happy with the alternator in my car. At a very low idle I get a negative current flow but otherwise it is always positive or zero when the battery is fully charged, as it should be. My volt meter shows 14 volts when driving (it is a 12 volt system). The battery never gets overcharged or goes flat and the alternator keeps up with any loads placed upon it.

A generator in good shape will provide all the current you need. The problem I have with the stock generator is the need to adjust the current with the third brush. In the past on other cars I have installed a voltage regulator (6 volt type) in a hidden location and used that to control the field windings. That eliminates the need to adjust the third brush for the seasons and the type of driving and eliminates over charging or under charging the battery. The generator with the regulator keeps up with the loads.

Do you have the manufacturer and model number of the 6 volt regulator? Did you use it on a Model A?