B Allis Chalmers
My father owned one of these little tractors that he used on his farm for mowing and raking hay. I have fond memories of driving it when I was a small boy, though at the time I am sure that I complained about having to.

These tractors are quite old, they were manufactured from 1938 thru 1957. According to the serial number mine was manufactured in 1950. The following links will provide some of the HISTORY and the SPECIFICATIONS of the B.

The one that my Dad owned was a very early model, probably pre-World War II. I can remember asking about what appeared to be a very small additional fuel tank on the right side, in front of the main fuel tank. He told me that originally the small tank held gasoline while the main tank was filled with kerosene. The tractor would be started on gasoline and allowed to warm up, then switched over to kerosene, which was much cheaper at the time. He also mentioned that the tractor originally came equipped with hand brakes and no electrical or hydraulic systems. The simple electrical system (battery, starter, generator, and lights), foot brakes, and hydraulics (pump, valve, single acting cylinder) were added through the years.

I thought it would be nice to purchase a “B” and restore it for my grandson to drive around. What follows will be the story of that restoration.

B on trailer, just purchased

This is a picture of the B that I ended up buying, still sitting on the trailer the day I brought it home. That’s my son-in-law Danny and my grandson Alex checking it out.

When I had first started talking about restoring a “B” Danny shared with me that his grandfather had taught him to drive a “C” when he was young.

I had looked a quite a few examples before finding this one. Lots of the ones that I saw for sale were in pretty rough shape from years of neglect. I found this particular tractor on my local Craig’s List. It looked good in the one photo with the ad but I had learned that a photo can be misleading. I tried to contact the seller but did not get a response, so I continued my search. A few weeks (and several tractors) later I noticed the ad was still on Craig’s List so I tried contacting the seller again and asked that they call to let me know if the tractor was still for sale. Late that afternoon I got a call advising that it was still available.

The owner said he and some friends had cleaned it with a steel brush and had it painted. Both fenders, battery box, oil pressure and water temperature gauges, and seat cushion were new. The tractor had been stored inside and not run for several years. My wife and I took my trailer and drove over to the sellers location, about 40 miles from our home.

It had what I like to call a 20 foot paint job, it looked good from a few feet away, but a lot of flaws were evident upon close inspection. The tires were all cracked and dry rotted. The engine turned and seemed to have good compression but would not start. But, it was all there and in fairly decent condition. We agreed on a price and I loaded it onto the trailer. I was the owner of a B Allis Chalmers!

The next week I called a friend who was into antique tractors and got him to come by and see if we could get it started. I had called Ray on my cell phone while I was running some errands and by the time I got home he already had it running. Turns out the points were stuck closed. But it would only run at idle, and just for a few minutes. So, I unloaded it and got it into the garage of my shop. I knew the gas was old so I took the sediment bowl off to drain the fuel. All that came out was a few drops at a time. No problem, I thought. I’ll just remove the sediment bowl assembly from the fuel tank. Still no luck! So, on to plan B.

I got Danny to help remove the fuel tank and we dumped the stale fuel out the filler opening. Then we took a brass brazing rod and broke loose all the crud from the fitting on the bottom of the tank. Then we stapled a scotch brite pad to the end of a wooden dowel and used it to scrub all the interior areas of the tank we could reach. Then we flushed the tank with the stale fuel to get the debris out, followed by a flush with a small amount of fresh fuel. We couldn’t get the crud out of the passages of the sediment bowl so a new one was ordered. So far, so good.

Sediment Bowl
When the new bowl arrived, we re-mounted the tank, installed the new sediment bowl, attached the fuel line and added fresh fuel. Success, the engine started right up! But our joy was short lived when we discovered that the engine seemed be be running only over a very limited range of RPM’s. To fast or too slow and it would shut off. Put the throttle at mid-range and it would start right up. And fuel was leaking out the vent in the bottom of the carburetor.
I knew from my youth that the carburetor of a B was notorious for leaking. I don’t think I have ever seen a B that doesn’t have a strain down the side of the engine from leaking fuel. Danny and I took the carburetor apart and found it filled with crud like the fuel tank and sediment bowl had been. Ethanol fuel, especially after it sits for a while, can cause a lot of problems. I thought about ordering a rebuild kit for the carb but was put off by our lack of success in cleaning the sediment bowl.
Old Carburator
New Carb - Vendor
I did a little research online and found a NEW CARB that was advertised as a replacement for the B so I ordered one. I would recommend this unit, but be forewarned that it takes quite a bit of fiddling to get it fitted to the intake manifold. As the ad states, it has “reversible linkage”. What this translates to is that you have to cut the throttle plate shaft off on the engine side of the carb after attaching the linkage so you can get the carb in place on the intake manifold.
I guess you could leave the shaft sticking out on the outside but I chose to cut it off and file the end smooth. The fuel inlet fitting is also slightly further forward than the original which necessitated fabricating and fitting a new fuel line. The outside diameter of the air inlet on the new carb was larger that the outlet of the air cleaner. While an adapter was provided that was the correct diameter, when it was fitted it wouldn’t clear the air cleaner. I was able to cut the adapter to reduce it’s length but I still had to reduce the length of the rubber hose connecting the carb to the air cleaner. While I was waiting on the carb to arrive, I removed the fuel tank, sanded, primed, and re-painted it. A lot of fiddling, but at last my B was running smoothly!
New Carb
Another weak point that I remembered was the 6 volt electrical system fed by a generator rather than an alternator. It is a fairly common upgrade to convert to a 12 volt negative ground system with an alternator, so that is the route I chose to take. Quite a few items have to be changed to accomplish the conversion, but none of them are particularly difficult. The first step was to remove the old generator, regulator, and 6 volt battery. A new 12 volt battery was installed but not connected.
I should mention that my B has a distributor ignition, rather than the magneto ignition that most B’s were equipped with. Apparently it was available as an option on the later versions. The ignition coil had to be changed to a 12 volt unit. Be sure to attach the negative side of the new coil to the wire going to the distributor! I removed the fan belt and temporarily attached the battery. The engine cranked right up and ran smoothly so on to the next step.
Distributor &Coil
Alternator & Bracket
I had a friend that runs an automotive electrical shop build me up an internally regulated Delco alternator with the body painted black. I also had him install the smallest diameter pulley that was available. I was able to find an alternator mounting bracket that fits the mounting holes for the old generator mounting bracket on E-bay. It was pre-painted and came with all new mounting bolts.

I mounted the alternator and wired it according to this diagram. I added a new 10 gauge wire from the alternator output back to the battery cable terminal on the starter solenoid because of the higher current output of the alternator. Progress is being made, on to the “dash”!

Alternator Wiring Diagram
Panel Box
Okay, I’ll admit, it’s not much of a dash. I took everything out of the box, sanded, primed, and painted it. An aftermarket voltmeter from the local auto parts shop was installed to replace the old ammeter. I also drilled a new hole and mounted an indicator light as shown in the alternator wiring diagram. I could not find an incandescent indicator light assembly locally, they were all LED. I ended up having to order one online.
A key switch and starter solenoid had been installed by the previous owner. They replaced the original push/pull ignition switch and heel actuator for the starter. I decided to leave them since it would make it easier for my grandson to operate. It was not necessary to replace the starter motor for this conversion. The old 6 volt unit just spins a little faster with the 12 volt system. For intermittent use like a starter it works fine.

Danny gave me a hand hooking up all the electrical, we hooked up the battery, and it fired right up!

Starter & Solenoid
Boarding Step
I discovered that for some reason it was more difficult to get on and off the tractor than I had remembered from my youth. I installed an aftermarket STEP that makes it much easier. It mounts using existing holes and comes powder coated AC orange.
Steering Wheel
The steering wheel was in rough shape, with the plastic coating cracked and falling off so I ordered a new one from the local TEMCO store. Just remove the castle nut, pull off the old steering wheel (be sure not to loose the key), install the new one, and tighten the nut. Job done!

As I said in the beginning, the tires were all cracked and dry rotted. One of the front tires wouldn’t hold air when I bought the tractor. I took it to a local shop and had a new tube installed. The rim was so rusted on the inside that they had to wrap it in duct tape to prevent the rust flakes from puncturing the new tube.

I had planned to have the rims sandblasted then prime and paint them but I decided that might not be a good idea given the amount of rust on the front rims. I found a source for NEW FRONT RIMS at a fairly reasonable price. I received a set of these rims and new 3 rib front tires as a Christmas gift from my family. They came primed but not painted, so I scuffed them with a scotch brite pad and painted them.
Front Rim
New Front Rims
I gave the paint a couple of days drying time to be sure they were fully cured then had the tires mounted. No more cracked front tires and no more rust, thanks to my family!
For safety, I mounted a stud mounted trailer tail light assembly in the existing holes in the frame under the seat on both sides. They are wired thru a flasher unit that I tie wrapped to the seat frame.
Warning Light
B AC Front Side View
So this is the way my little “B” looks at this time. I still need to get the rear rims sand blasted, prime, and paint them, and of course a new set of rear tires. But these will have to wait on more time and more money!
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  1. Wendy

    Thanks for the info. I’ve got a 1943 Allis B which I’m wanting to covert to an electric start. She’s crank start at the moment and can be quite a chore for me when she doesn’t want to play ball… I’m having trouble tracking down a starter kit in the UK, if you can give me any suggestions where to start…plenty of parts in the U.S.A but pricey postage.
    Regards, Wendy. 🙂

    • rick@www.ricksworkshop.com

      Sorry to hear that you are having troubles hand starting you B. Usually they start easily when properly tuned.

      As far as adding electric start, I believe the changes required are quite significant. From what I can discover, the frame casting to the rear of the engine, called the torque tube, must be replaced. Also the flywheel would probably need to be replaced with one with a ring gear. All this in addition of the battery box, battery, starter,generator or alternator, and all the associated wiring.

      I would be tempted to try a thorough tune up first. If you are still interested adding electric start I would be glad to help you try to track down the necessary pieces.


      • Walter Petchey

        I have an A-C 1939 B model
        it starts on the crank handle ,
        Do you know in which year the factory introduced the starter motor to the tractor.
        Many thanks

        • Richard Courtney

          I do not have any first hand information, but according to the discussion on the Allis Chalmers Forum starting in late 1939 or early 1940.

      • Pam

        I have a Allis Chalmers 1948 tractor, ID no. C 26058..
        How does the positive and negative cables go.

        • Richard Courtney

          Is it still set up for 6 volts or has it been converted to 12 volts?

          If it is still 6 volts, it will be positive ground.
          If it has been converted to 12 volts , it will be negative ground.

          Hope this helps. Good luck

    • Randy cagle

      I have almost completed my 1948 b allic. I have owned it for 25 year’s took it apart sand blasted front hood, tank.look good. New carb. Just like you cut the bolt on back. Changed to alternate gauge like you. Put a refused from 12 down to six to coil.still trying to get wired correct. But it run like new.

      • Richard Courtney

        Hi Randy,
        Sounds like you have been doing good work on your B.
        If I can be any help with the wiring let me know.

        Good Luck,

  2. Danny

    I like where you have spent money on that b. Didn’t waste a dime in my opinion. That Allis will be around a long time. I have a d15 and fix up now and then. A little attention goes a long way on these old tractors.
    Good job!

  3. Mike Petroelje

    I have a 1939 AC model B, it’s crank start with a magneto. Would like to add headlights, do you have any suggestions on how to do this? Can I tie them into the magneto or do I need to add a 12 volt battery and generator?

    Thank you!

    • Richard Courtney

      Hi Mike,
      I am afraid you cannot use the magneto to power headlights.

      The magneto is designed to generate a high voltage pulse
      to energize the spark plugs.

      If you want lights you will need a generator or alternator,
      voltage regulator, battery, lights, and associated wiring.

      The alternator with internal voltage regulator like I upgraded
      to would probably be the easiest.

      If you have any more questions I would be glad to try to answer them.


  4. Chris

    Hi Rick,
    Did you have to use a resistor for the coil? I’ve heard you have to so the points won’t burn out however that statement is from people who haven’t done a conversion.

    • Richard Courtney

      I purchased a 12 volt coil so no resistor required. Be sure to use the correct polarity when connecting the coil.

  5. FB

    Beautiful job, and your information and presentation was great. I inherited a AC B and an AC WD45. The 45 still runs like a top, the B just needs work. The pictures were very helpful!

    • Richard Courtney

      Thanks for the comment. My Dad had a WD on the farm when I was growing up.
      He purchased the WD and a Rotobaler (early round baler) at the same time.

      I hope you enjoy your tractors and good luck with the B.


    • Gloria Lambert

      I have a 1938 AC B. The fuel tank is all rusted out. Any suggestions for repairing it? Or do you know where I could get a replacement? I am in California.

      • Richard Courtney

        Hi Gloria, I really would not recommend trying to repair. You might try http://www.yesterdaystractors.com for a replacement part.

        Good Luck

  6. Gene LaLone

    J have a Allis Chalmers tractor I’m not sure if its B or C how can I tell?

    • Richard Courtney

      Hi Gene, Sorry for the delay in responding, been on vacation.

      Don’t know much about the C, but every one I ever saw had narrow “tricycle” front wheels while the B had wide front wheels.

  7. Paul

    I have a 1945 allis chalmers C . It runs very well however, the other day it started right up then died when I tried to get it started again it wouldn’t do anything, no sound or anything. The battery is fully charged, so I thought it might be the starter so I had it checked. I then checked the wiring connections for corrosion, still nothing. Does anyone have any suggestions?

  8. Brandon

    Hi Richard,

    Great restore! I was given a 1945 B from my Dad. He had one growing up on their small farm. It runs great, however it is all of a sudden draining the battery. The switch for the Headlights is off as far as I can tell. I would like to eventually convert to 12V but for time being am trying to figure out what keeps draining the battery. If i put the multimeter on it i can literally watch the voltage drop. Any ideas? Thank you

    • Richard Courtney

      Sounds like you have a serious drain on the electrical circuit.
      Have you checked the voltage regulator for stuck or burned contacts?
      Probably has original rubber/cloth braid wiring so be sure to check
      for frayed wiring, especially at penetrations thru metal parts or at clamps.

      Good luck

  9. James

    this is a great source of info! i just picked up my first vintage tractor, in fact i got two, they are both B models, one is a 1940, the other is a 1944. Should i be running leaded gas in them or is unleaded ok?

    • Richard Courtney

      I have been using unleaded without ethanol with no issues.
      Of course, I don’t run it very often.

      I do not know what type fuel my dad used, there was a 500
      gallon tank on the farm that was used to fuel the B and a
      WD with. I know it was “regular” grade fuel, so given the
      time frame, it was probably leaded.

      Good Luck!

  10. Lynda

    I have the same Allis Chalmers B tractor. Mine in from 1952 my dad left me to brush hog the fields. Do you sell parts? Or where do u order parts from? I’m from Western NY. It needs an alternator

    • Richard Courtney

      Sorry, I am a hobbyist, don’t sell parts.
      You might try http://www.yesterdaystractors.com for parts.

      The B came with a generator and a 6 volt electrical system.
      If yours is equipped with an alternator it was probably
      converted to 12 volts and the alternator at some time.
      Your best bet might be an independent auto electric shop.

      I have noticed with mine sometimes I have to run the engine
      at high RPM for a few seconds to get the alternator to start
      charging, then reduce to whatever speed you desire.

      Good Luck with your B.

  11. WoodDuck

    Great article and a real beaut machine there Rick 🙂

    • Richard Courtney


  12. Lee Lovstad

    I don’t have a B at present but having grown up with WDs and WCs I enjoyed immensely the detail and pleasure of this restoration. Hopefully I can do a restoration of my own someday.

    • Richard Courtney

      I’m glad you enjoyed the description of my restoration.

      I need to get around to updating it with the remained of
      the work I have completed, mostly powder coating the rear
      rims and installing new rear tires. Hopefully I will have
      an opportunity to do the update soon.

  13. Sharon

    Nicely done. Will be checking back for updates. Thanks for sharing.

    • Richard Courtney

      Glad you enjoyed it!

  14. Sherwin Cullison

    I enjoyed the description of your restoration. I have a 1939 AC Model B which I bought in 1984 when I first moved out into the country. I’m just a “hobby farmer” so it continues to serve me well when I need it. Mine starts by cranking and it usually starts fairly quickly. The great part about the magneto version is that there’s no battery to go dead over the winter when I’m not using it. I’m in the middle of trying to change the fuel sediment bulb but it isn’t as easy as I’d hoped. I finally found a correct size wrench to remove it but it’s too close to a bracket (I think it holds the fuel tank in place) to turn the sediment bulb assembly past the shut-off valve. Do I have to remove the tank to do this? Thanks.

    • Richard Courtney

      I had the fuel tank removed when I replaced mine. All you need is a large flat blade screw driver to remove the tank. Just loosen the slotted bolt and remove the retaining strap and it lifts right off. Good luck.


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