Allis b 6 to 12 volt conversion
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=169859
Printed Date: 23 Aug 2025 at 7:17am
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Topic: Allis b 6 to 12 volt conversion
Posted By: Kevin-WC
Subject: Allis b 6 to 12 volt conversion
Date Posted: 06 Apr 2020 at 3:23pm
| I just bought a 39 b and would like to convert it to 12 volt ,I have never had a tractor that still has a mag on it ,I know I'll need a GMC alternator but do I replace the mag with a gm distributor ? |
Replies:
Posted By: WF owner
Date Posted: 06 Apr 2020 at 4:06pm
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On my 39, the only wires on the tractor are spark plug wires. There is no hole in the block to mount a generator or alternator, no hole in the torque tube for a starter, no battery box and, I'm sure, no ring gear on the flywheel. I believe the governor drive is different for a distributor than a mag. You will need to mount a (4 ohm) coil.When switching from an existing generator to an alternator, you should switch from an ammeter to a volt meter. Ammeters are not built to flow the current that an alternator puts out and all power flows through the alternator,
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Posted By: mdm1
Date Posted: 06 Apr 2020 at 4:06pm
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I understand that the B's didn't have electric start until mid 1940 starting with serial number 43220. I could be mistaken and someone with more knowledge will correct me. Good luck with your B. ------------- Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK! |
Posted By: Joe(TX)
Date Posted: 06 Apr 2020 at 4:11pm
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No need to replace the mag. Generator/alternator is only needed if you have a starter on a tractor with a mag. ------------- 1970 190XT, 1973 200, 1962 D-19 Diesel, 1979 7010, 1957 WD45, 1950 WD, 1961 D17, Speed Patrol, D14, All crop 66 big bin, 180 diesel, 1970 170 diesel, FP80 forklift. Gleaner A |
Posted By: Kevin-WC
Date Posted: 06 Apr 2020 at 4:33pm
| I could be wrong about the year of this tractor because it does have a starter |
Posted By: Kevin-WC
Date Posted: 06 Apr 2020 at 4:35pm
| If anyone knows where I could find a wiring diagram that would really help, thanks |
Posted By: Bill Long
Date Posted: 06 Apr 2020 at 4:35pm
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Kevin, Thank you for getting one of my favorite Allis Chalmers Tractors the B. Check and see if you have an opening in the torque tube for a starter, a flywheel with provisions for a starter ring gear, a block with the wherewithal to mount a generator, and torque tube with the mountings to accommodate a battery box. If you have those items on your tractor and it is electrified with 6 volts contact SteveNJ. He is our residentl electrical expert and has the knowledge and parts to do what you want to do.
Take good care of my favorite. Good Luck! Bill Long ps: Here I am with him - on left. You can see the telephone number on the B&B sign.  |
Posted By: mdm1
Date Posted: 06 Apr 2020 at 5:08pm
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There is always a chance someone may have converted it to electric start. Go to this page for a wiring diagram. If the tractor starts and runs leave the mag on it. The mag is totally independant of the battery system. The battery turns the starter and runs any lights. If you convert to 12v it has nothing to do with the mag. http://dueyschutter.freeservers.com/photo3.html" rel="nofollow - http://dueyschutter.freeservers.com/photo3.html This page will show you the location of the serial number and how to tell the year. https://www.tractordata.com/farm-tractors/000/0/0/3-allis-chalmers-b.html" rel="nofollow - https://www.tractordata.com/farm-tractors/000/0/0/3-allis-chalmers-b.html Hope it helps! ------------- Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK! |
Posted By: Gerald J.
Date Posted: 06 Apr 2020 at 5:12pm
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The magneto will work no matter what the battery voltage is, its not powered from the electric system, just by rotation. Some starters will handle 12 volts though built for 6 volts, but not all will stand the voltage rise without internal damage. The voltmeter is easier to install but since an alternator will put out more current than the old 6volt generator the ammeter needs to be replaced with one rated for at least as much current as the alternator. I prefer an ammeter on the battery charge and load wire so it can indicate whether the battery is taking a charge or is supplying loads. A voltmeter can't show the battery really charging unless it is connected to the battery posts, but when the tractor isn't used the voltmeter connected to the battery posts will run the battery dead in a few weeks. And then the light bulbs all have to be replaced along with electric fuel gauge sensors and indicators. There is an original wiring diagram in the shop manual: http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf" rel="nofollow - http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf There have been alternator wiring diagrams posted on this forum in the past few days. Gerald J. |
Posted By: WF owner
Date Posted: 06 Apr 2020 at 5:22pm
| I have a WD with a mag. All I did was replace the 6 volt battery with a 12 volt. I only use it in the summer and I stick an automatic battery charger on it after I have started it several times. It works for me without costing much and unless someone opens the battery box, it looks original. |
Posted By: chaskaduo
Date Posted: 06 Apr 2020 at 6:04pm
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This article is from ROD(NH) http://rodnh.byethost12.com/acb/alternator/alternator.htm?i=1" rel="nofollow - http://rodnh.byethost12.com/acb/alternator/alternator.htm?i=1 HTH ------------- 1938 B, 79 Dynamark 11/36 6spd, 95 Weed-Eater 16hp, 2010 Bolens 14hp |
Posted By: TedBuiskerN.IL.
Date Posted: 06 Apr 2020 at 7:20pm
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My question is Why change? Six volts will spin a B like a top if the correct heavy gauge wires are used. ------------- Most problems can be solved with the proper application of high explosives. |
Posted By: steve(ill)
Date Posted: 06 Apr 2020 at 8:11pm
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Yea, if your just getting started on a project and checking it out, you DONT need an alternator right now... Just put in the 12 v battery with good cables and starter switch and get it going........ Put it on the portable charger once a month for battery maintenance... Mag is good to go. ------------- Like them all, but love the "B"s. |
Posted By: WF owner
Date Posted: 06 Apr 2020 at 9:39pm
But if you use the lights, they get VERY bright for a VERY short time (and then there is darkness!). Don't bother asking why I know.
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steve(ill) wrote:Posted By: Michael V (NM)
Date Posted: 06 Apr 2020 at 9:55pm
| I'm sorry,,, this question is getting to be a peeve of mine,,, does anybody have the intellect to do any research at all anymore? this question has prolly been asked 5,456,985 times on various forums, and there are prolly about 2,376,377 you-tube videos on how to do it...dammit, google, bing, ask, yahoo get you zillions of places to look.... |
Posted By: chaskaduo
Date Posted: 07 Apr 2020 at 5:28am
He is researching.  ------------- 1938 B, 79 Dynamark 11/36 6spd, 95 Weed-Eater 16hp, 2010 Bolens 14hp |
Posted By: WF owner
Date Posted: 07 Apr 2020 at 5:54am
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Relax !!! We've all asked questions on this forum, that have been asked before. The forum is a sharing of ideas and knowledge. We can all use more of both ! A wise man once told me that the only dumb question was one that was not asked.
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Posted By: Steve Wilkens
Date Posted: 07 Apr 2020 at 8:49am
| It is a really easy conversion. I did it to my 39 B that I built as a custom lowrider. The toughest part, which isn't tough is make the brackets for the alternator. Use the GM one-wire alternator. Once you have that installed, run a 10ga. wire to the plus side of the amp gauge. Then from the negative side of the amp gauge run another 10ga. wire to the battery. If you have lights, run a fused 12 ga. wire from the negative side of the amp gauge to the light switch. You are then done, except for changing lights out to 12 volt if so equipped. |
Posted By: HoughMade
Date Posted: 07 Apr 2020 at 9:16am
Yeah, if a guy wants 12 volts for some reason, more power to him, but if it isn't starting well, find out why and fix that because a properly tuned mag and engine will light off with about 1 1/2 seconds of cranking. THEN make the decision as to whether you want 12 volts. Just my 2 cents- good luck! ------------- 1951 B |
Posted By: mdm1
Date Posted: 07 Apr 2020 at 9:21am
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I guess if he would say why he wants to convert it that would make it easier for people to offer suggestions. ------------- Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK! |
Posted By: HD6GTOM
Date Posted: 07 Apr 2020 at 9:45am
| Mine was converted to electric start with a different torque tube and flywheel. Someone did a very professional job of mounting the Genny under the seat and running it off the PTO shaft. I had the starter converted to 12 volt and run a 12 volt battery. Starts 10 times easier than the old 6 volt and I can get a battery anywhere they sell them. Still has the mag which I will get rid of sometime this summer. |
Posted By: PaulB
Date Posted: 07 Apr 2020 at 10:11am
I've been making a nice neat bracket to put the GM alternator on the Little block AC motors. It will even fit in behind the drag link on C & CA tractors.  ------------- If it was fun to pull in LOW gear, I could have a John Deere. Real pullers don't have speed limits. If you can't make it GO... make it SHINY |
Posted By: Steve Wilkens
Date Posted: 07 Apr 2020 at 8:48pm
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that bracket look great Paul! |
Posted By: Dave Hawk
Date Posted: 03 May 2020 at 8:24am
| I have a WD with the power crater 45 motor on it. I think it's stlll a 6 volt system but has an 8 volt battery. I don't know much about it, but I have to buy a new battery every year and the 8 volt is getting harder to find. I jump start it with a 12 volt. How do you tell if it has a magneto? What is the best way to convert it to 12 volt? Thanks |
Posted By: jaybmiller
Date Posted: 03 May 2020 at 8:39am
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best way... contact Steve @B&B.....he has all the PROPER options and parts.... buya complet 'kit' including a wiring harness.. ------------- 3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water |
Posted By: steve(ill)
Date Posted: 03 May 2020 at 8:41am
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Dave, your ignition system has either a magnito or a distributor and coil... Look at the spark plug wires. They all run to a black cap on the mag or dist... If you have 4 wires running to the 4 plugs, that is a mag... If you have a fifth wire in the center that comes from a COIL, then you have a distributor. The COIL is powered from the battery and sends a SPARK to the Distributor and it distributes the spark to the 4 plugs in rotation.. The MAGNITO does not need the battery or external coil. It has an internal coil and generates the spark similar to a lawn mower engine. ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 03 May 2020 at 8:46am
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Dave, depending on how much you use the tractor, you might not even need to recharge the battery very often ? You can put the 12 volt battery in place of the 8 volt and as you say, it will startup easy.... Just take the wires off the generator and tape them up so it will not charge and use the generator as a belt tensioner.... Then put the tractor on a plug in battery charger after you use the tractor . If you have a mag, it will run without recharge for several days. If you have a Distributor, then the coil is using the battery to form the SPARK and it will run the battery down in a day or two of use.... an external battery charger can be used as a temp "FIX" until you decided you want to install an alternator and rewire..... or maybe never. ------------- Like them all, but love the "B"s. |
Posted By: Steve in NJ
Date Posted: 03 May 2020 at 3:50pm
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As mentioned, we offer a complete 12V conversion kit for the B model. Be glad to help ya out. Visit our website. There is a lot of good information on converting to 12V. Also, you can see the kits we offer along with the optional Alternator bracket. HTH Steve@B&B bb-customcircuits.com ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: HoughMade
Date Posted: 03 May 2020 at 9:14pm
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My 2 cents in a short video- had I let the carb bowl fill before trying to start it, it would have lit off immediately. 6v pos. ground, generator cleaned, but otherwise stock, brushes replaced in starter, wiring replaced, rebuilt mag, all this 2 years go. The video is from April, hadn’t started since January, not on a battery tender. I used it regularly until October, started it once in January, then not again until April. I contend that if everything is in good repair, 12v is completely unnecessary for reliable starting of a B. If additional or brighter lights or accessories are needed, 12v makes sense. https://youtu.be/RUHDBlDCKSs" rel="nofollow - https://youtu.be/RUHDBlDCKSs ------------- 1951 B |
Posted By: Dave Hawk
Date Posted: 04 May 2020 at 6:16am
| Thank you Steve. It does indeed have a coil and distributor. |
Posted By: Dave Hawk
Date Posted: 04 May 2020 at 6:29am
| I do use this tractor on a daily basis. I mow with a Dixie Cutter behind. The 8 volt battery that came on the tractor lasted several years, but now I have to buy one every spring. Maybe the generator isn't working properlty. Although I am a tool & die engineer, I am not very elec. savy, so I may attempt the 12V conversion with a kit if the directions are clear and concise. |
Posted By: Steve in NJ
Date Posted: 04 May 2020 at 1:33pm
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All of the instructions in my kits for the early Tractors are very easy to read and understand. I also include a color coded wiring diagram. All wiring is numbered, so its like color by number. And if you have a question about anything in my kits, I'm a phone call away and can walk you through it while you're standing next to the Tractor. Most of our customer's are not up on electrical and they all tell me electrical scares them. After they install one of my kits, some call me and hold the phone up so I can hear the Tractor running. LOL! Not only are they happy that they did it themselves, I'm happy to because they got their Tractor all rewired and back in service and they had fun doing it to! Steve@B&B bb-customcircuits.com ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: Dave Hawk
Date Posted: 05 May 2020 at 6:11am
| Thanks Steve, I will be ordering your kit soon. Sounds like a relatively painless install for a novice like myself, and with your support, it should be a success !! |