12v '38 Ford - confirm polarizing method

[46wischris]

Finally got new tires mounted on the '38 we bought earlier this year. I've only started it a few times, wasn't going to take it out before replacing the 50 year old tires. I just noticed that the amp gauge shows discharge when revving the engine. The seller had installed a new battery, so I assume I need to polarize the system.

Background - a few years back the '38 was converted to 12v negative ground with all new wiring. From L to R, VR reads Gen, Field and Batt. The VR has just one wire going to it, at the Field terminal. Researching the topic of polarizing, I've gotten confused. Am I supposed to 1) remove the Field wire and touch it to the Bat terminal, or 2) touch Gen and Batt terminals, or 3) leave Field connected and touch Field and Bat terminals together?

I also noticed that the negative battery cable grounding to the block is much heavier gauge than the positive cable going to the solenoid. Is that OK?

[Bob C]

That look's like and original regulator that isn't even hooked up.
Do you have a generator or an alternator?

[46wischris]

It has a generator as far as I can tell, but also possible that it's an alternator disguised as a generator. Should I supply a photo of the generator?

[Bob C]

Picture would help.

[petehoovie]

Originally Posted by 46wischris

Finally got new tires mounted on the '38 we bought earlier this year. I've only started it a few times, wasn't going to take it out before replacing the 50 year old tires. I just noticed that the amp gauge shows discharge when revving the engine. The seller had installed a new battery, so I assume I need to polarize the system.

Background - a few years back the '38 was converted to 12v negative ground with all new wiring. From L to R, VR reads Gen, Field and Batt. The VR has just one wire going to it, at the Field terminal. Researching the topic of polarizing, I've gotten confused. Am I supposed to 1) remove the Field wire and touch it to the Bat terminal, or 2) touch Gen and Batt terminals, or 3) leave Field connected and touch Field and Bat terminals together?

I also noticed that the negative battery cable grounding to the block is much heavier gauge than the positive cable going to the solenoid. Is that OK?

[ndnchf]

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Clear, well lit photos of the generator from different angles are needed to see what you have. '38 was originally a 3-brush generator with cutout.

[46wischris]

Right and left side photos, and side view toward the front. On the back is the brand name Power Gen. I guess I have a 1-wire alternator.

[petehoovie]

Originally Posted by 46wischris

Right and left side photos, and side view toward the front. On the back is the brand name Power Gen. I guess I have a 1-wire alternator.

[38 coupe]

Yes, one wire alternator.
The ammeter will read backwards unless the wire running through it is removed and run the other direction. Fords built from 1928 through 1955 were originally positive ground. When the switch to 12V negative ground happened the electrons flowing through the ammeter started going the opposite direction.


The regulator on your car is no longer hooked up. It is an interesting unit. Ford first offered regulated generators in 1938, but I haven't seen any in use. Both my 38s have cutout generators. Your car apparently was built with the two brush type regulated generator. Those regulators were short lived production items, replaced by the larger size regulators used in most Fords through the end of generators. I would be interested in buying the regulator from you as a curiosity if you ever feel like removing it from your car.

[46wischris]

Mystery solved, thanks one and all. I'm always grateful for the wisdom found in the forum, and for the willingness to share it.

38 coupe, curious as to the level of effort required to run the wire in the other direction. If the ammeter is doing the opposite of what it reads, then it's charging and I'm happy. Also curious as to why there'd be a wire connected to Field if the regulator is no longer hooked up. Appearance sake? If you have an inop regulator you want to swap for this one, let me know.

Backstory: In April I found this '38 on Hemmings Classifieds listed by motorlandcars.com in Maine and after striking a deal had it shipped to WI. Here are photos of the car: https://www.motorlandcars.com/vehicl...xe-convertible (I didn't pay that price, by the way). The prior owner is in his 90's and the '38 was apparently his pride and joy. I heard from Motorland that he was delighted that the car would be cared for and driven, and he even kicked in half the shipping cost after the deal was struck. That was a pleasant surprise. I've had a couple of enjoyable conversations with him since buying the car. He'd owned it for 23 years, and the owner before him had it for 20 years. The owner before him replaced the motor with one out of a '49 Merc, which I didn't know until I started looking through the big folder of ROs and other docs that came with the car. Amazingly, ROs over the years totaled nearly $27k, all mechanical repairs/upgrades with the exception of $3k for a new top and boot and $2k for reupholstery, doors & floor. Trans rebuild and clutch assembly, 12v wire loom & related upgrades, modern shocks, new brakes & lines, starter, u-joints, Pertronix ignition & related items, and numerous other expected repairs/replacements. I guess he just loved getting his car fixed up. All I've done is replace the '90's vintage Coker Classic bias plys with 6.00x16 Diamond Back radials. I won't drive any distance on old tires, having learned my lesson the hard way. The bias plys had been put on by the 20-year owner and looked practically new. Likely that in the past 43 years this '38 may not have been driven much at all, since the 23-year owner said he'd only put about 500 miles on it. An old repaint holding up fairly well, just oxidized. Haven't found any rust. Odometer shows 24.5k mi, but who knows.

I've had 26 wonderful old classics over the past 45 years, with the 8 remaining ones sold after I retired and we prepared to move to a place without a 60x60 workshop. I miss them all, but once we got settled I planned to find just one old car, not counting the '98 BMW Z3 I bought for my wife a dozen years ago. Coming across this Ford sedan convertible was an unexpected stroke of luck, in all respects. Feels like a reward for the years of buying cars that were sometimes not as advertised, but eventually selling them all in better shape than when I got them, always reasonably and with known warts fully disclosed. I've learned along the way that while there's very little that I might know about solving a particular car problem, there are people who know exactly what's needed. Thank goodness for forums, car clubs and the rare shops that appreciate old iron.

Only real issue with this '38 was getting a WI title. I submitted the prior owner's Maine registration to DOT in April, but the serial number was only 4 digits. The DOT counter person said those 4 digits were assigned to a '70's travel trailer. Didn't matter that the 2002 BOS showed that same 4 digits being the serial number. I still submitted the title request and paid the fee, hoping DOT would somehow resolve the issue and send me a title. That was some magical thinking. I eventually was informed that if I couldn't supply accurate serial number and purchase evidence I'd have to pay for a costly WI bonded title, meaning DOT wouldn't assign a VIN and clear title until a 5 year waiting period was over. Setting aside the magical thinking, I used this forum to learn where I could find the serial number, uncovered it on the frame rail and took a photo. I also discovered that the 4 digits were from the body number placard on the firewall, so I took a photo of that as well. After 3 or 4 DOT phone transfers, I was able to get to someone in the Vehicle Research Unit, the ultimate arbiters for issuing titles when complications have been identified. A couple weeks after supplying the VRU with the frame rail and body number placard photos along with a copy of the BOS from Motorland, I finally received a title with the correct serial number. When I was buying the car, I asked if the registered serial number matched what was on the car, and they said it did. Partly true, because it did match the body number placard. Even if I'd been smart enough at the time to realize that the car's serial number couldn't possibly be just 4 digits, would I have bought it anyway? For what I was able to get this lovely '38 for, yes indeed.