swapping 24 to 12

[junkyardog]

I'm thinking of doing a swap to 12 volt... i know the lights all have to be done. what else will need to be changed. i will be getting rid of most of the wiring..

[w30bob]

Well, just about everything the 24v touches, including;

Starter
Alternator
Regulator
Horn
Gauges and Senders
Circuit Breakers
Ignition coil (or just put in a 12v distributor)
Fan motor for heater (if you have one)
And all the bulbs, as you mentioned

I may have missed something...............

regards,
bob

[just me]

Why are you thinking of doing it? There is no difficulty getting 24v parts and maintaining the system. I did a hybrid swap and am 12 and 24v. There are some hidden issues doing the swap (and keeping the original appearance.)
I would have gone all 24 if I had the generator, regulator, starter and distributer still. But a civilian engine had been swapped when I bought my truck.
I have 24 instrumentation to retain stock guages and backlighting. Everything else is 12v. Had to make floor controls for the starter to retain foot start and not cut any holes for key switches. The circuit breakers work 12 or 24V. They trip on current, not voltage.

[billy]

Why are you thinking of doing it? There is no difficulty getting 24v parts and maintaining the system. I did a hybrid swap and am 12 and 24v. There are some hidden issues doing the swap (and keeping the original appearance.)
I would have gone all 24 if I had the generator, regulator, starter and distributer still. But a civilian engine had been swapped when I bought my truck.
I have 24 instrumentation to retain stock guages and backlighting. Everything else is 12v. Had to make floor controls for the starter to retain foot start and not cut any holes for key switches. The circuit breakers work 12 or 24V. They trip on current, not voltage.

did you make a build thread or anything?
i am in the same boat
engine swap and the po rewired the lights so they work

[52PLOWERWAGON]

Well, just about everything the 24v touches, including;

Starter
Alternator
Regulator
Horn
Gauges and Senders
Circuit Breakers
Ignition coil (or just put in a 12v distributor)
Fan motor for heater (if you have one)
And all the bulbs, as you mentioned

I may have missed something...............

regards,
bob

you have to swap oil pumps to swap distributers (different style drive tang)

[just me]

I have no build thread, but the info was put on the facebook page along with some pics.
Basically, when I got my truck, there was not an inch of good wiring left. The original harness had rotted and the PO wasn't exactly good with wiring.
So, I bought an entire new harness for a B1 with Douglas connectors (so I could have turn signals) from Joe at Vintage Wiring of Maine. Told him I didn't need the 24V charging wiring or the distributer plug. He provided a pigtail for the distributor and I made the charging harness from the correct wire and Douglas connectors.
Installed the harness and 12V lamps in the lamp housings, headlamps, High beam indicator and instrument lights.
Intercepted the lead to the Breaker that feeds the spider harness and ran it through a 10amp 12V to 24V DC convertor and fed that to the breaker/spider.
Now, the instruments and all of the associated senders are still 24V and do not have to be changed. You keep the red backlighting. (With the loss of the dim setting as the resistor in the 3 lever switch drops the voltage too far to see the filaments. (If you have a switch you can open, you could change that resistor.))
The generator gauge now shows the condition of the convertor and I added a 12V gauge and ammeter to show condition of charging system under the dash. One other thing however, the stock generator gauge will read in the yellow band as the convertor puts out 24V and that is the yellow band showing not charging, Green starts at 26V.
I recalibrated the gauge so it points into the green at 24V.
Since the 12V starter didn't have the foot switch, I mounted a CJ2 start pedal on a fabricated bracket in the original location and made cables from Batt to switch to starter. I did not want a start solenoid, keyswitch or any of that stuff.
It has been working for a year now with no issues and I use the truck as a daily driver.

[Elwood]

you have to swap oil pumps to swap distributers (different style drive tang)

When I purchased my '54, it had been crudely converted to 12v, but the original distributor (and oil pump) was still in it, albeit with an external coil. The conversion can be done without swapping out the military distributor or oil pump.

[TAK824]

Ah, I see that many others have the same problem I'm running into.....sort of. I have an M-43 just recently acquired. The wiring is in fair shape, except where it was exposed to heat and the elements. Everything under the electrical tape is still pliable and good. The PO had evidently started to convert over, but didn't get very far, fortunately. He did NO changes to the wiring, except to install cheesy turn signals, and fed them off one battery. He also installed an automotive 12 volt hot water heater, also 12 volt, and run it off the same battery. It also appears that he was GOING to change over, as the engine is out of a Plymouth, but oddly enough still had most all the military items on it, right down to the oil pump and distributor. Even has the 24 volt starter on it. It does look like he was going to change that to 12 volt. The generator is missing, but the 24 volt regulator is still there. The spark plug wires were also missing, although it had the correct plugs in it. I am going to RETAIN all of the 24 volt system, and replace whatever is missing, which really isn't much. In regards to the bad sections of wire, I am using a product made by "Dip-It" that is a liquid electrical tape. Others I know have used it, with great success. But my using it is mainly because probably 80 percent of the wiring is still good. A BIG plus with staying with the 24 volt system also is the total AMP load. If I were to drop to 12 volts, then the amp load would effectively double. Now I understand how they got away with a 25 amp generator to run everything, at least everything in an ambulance. A patient area heater, two ventilation fans, surgery light, to name a few. Checking the amp load at 24 volts, it's actually pretty small.