B Wiring
Printed From: Unofficial Allis
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=75610
Printed Date: 11 Sep 2025 at 1:00am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: B Wiring
Posted By: EagleTDL
Subject: B Wiring
Date Posted: 22 Aug 2013 at 7:48pm
Question for the group... Through some of the links you folks have posted on here I've fallen into a rabbit hole or two ( ), but one of the links (and I can't remember which one) took me to a site where it was mentioned that some of the older B's didn't come with any wiring at all, other than the spark plug wires. This same article/website is where I learned that the little tab on the side of the magneto was actually a grounding strap, if you will, and that's how you shut the tractor off. Neat! On my B, I've got a two-position switch on the steering shaft support, see below:   As you can see, one of the wires loops back on itself and is attached to the switch mount, which I'm assuming is part of the grounding circuit for the switch. The other wires runs down to the mag, as you can see below:  When connected to the grounding strap on the mag, this would make your "kill" circuit, if you will... My question is what does this harness really look like on a B that has this type of switch?? How was the wiring run down the tractor? Or, as I'm suspecting, is this a home-made kill switch?? As always, any info would be appreciated and thanks for your time! Eagle |
Replies:
Posted By: Steve in NJ
Date Posted: 22 Aug 2013 at 8:02pm
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The real early B models were crank start. Most didn't have provision on the block for a Generator to mount. (BE engines) Those particular units didn't have lights either so there was no need for a Gennie. As time progressed, so did the B, and lights, Generator, and electric start were added. The B/C blocks had bosses to mount a Generator. As those accessories were added, of coarse so was a wiring harness. On B models that were equipped with lights, a Battery box was added between the tool boxl and the steering column support post. Its at this post an instrument panel or Ammeter panel was mounted housing the Ammeter, three pos. charging switch, and Mag kill switch. That particular switch that's on your Tractor someone added on. Moving the mag kill switch near the driver is much safer should something happen where you would need to shut the engine down quickly. HTH |
Posted By: Chalmersbob
Date Posted: 22 Aug 2013 at 9:54pm
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The tractor that you have didn't have that, or any, switch to kill the engine, as Steve mentioned. The throttle quadrant linkage was set up so when you pulled the lever all the way back, the engine would shut off so there wasn't any need for wires and a kill switch. Bob ------------- 4 B's, 1 C's,3 CA's, 2 G's WD, D14, D15, B-1, B10, B12, 712S, |
Posted By: CTuckerNWIL
Date Posted: 22 Aug 2013 at 9:58pm
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SO did any B's come with a WICO mag? I kinda thought most all had the Fairbanks Morse mags.
------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: CAdon
Date Posted: 22 Aug 2013 at 10:16pm
hey, eagle - you seem to have caught on quickly how to get good advice fast on this forum: post pictures and ask specific questions. thanks, that also makes it easier for others (like me) to learn along with you.  for what it's worth... i knew i was gonna run out of available time all too soon so to give myself time to deal with other issues (and tractors) i got a very complete wiring system from steve (above) like many on here have done. and even that was a quite educational process, discussing the options. either way you go, please keep havin' fun and posting pictures! ------------- 52 CA, 41 B and a little B1 oh, yeah... and an 8N ford snuck in there, too. |
Posted By: CAdon
Date Posted: 22 Aug 2013 at 10:26pm
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tuck - owners manual makes no reference to other than f/m, but i know i did see a wico on either a B or a CA recently. likely just another "replacement"? ------------- 52 CA, 41 B and a little B1 oh, yeah... and an 8N ford snuck in there, too. |
Posted By: EagleTDL
Date Posted: 23 Aug 2013 at 7:21am
Yeah Steve, it does, so thanks for that! I've seen the battery box along with the other controls/switches in my manuals, so I know I've got something "a little different"... Seems like Grandpappy was a bit of a tinker-er, if you will??  Or, he may have bought it this way?? As you mention, for safety reasons, I'll keep the switch and clean up the wiring... Maybe run it in some type of small wire loom or something??
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Steve in NJ wrote:Posted By: EagleTDL
Date Posted: 23 Aug 2013 at 7:22am
Now that's something I didn't know! Great info, appreciated!! I'll certainly check that functionality out when I get it running, but I'll also keep the switch just in case...
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Posted By: EagleTDL
Date Posted: 23 Aug 2013 at 7:24am
Maybe so Don?? I think I'm gonna name this one "Franky", short for Frankenstein since it seems to be a collection of pieces parts!
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Posted By: Bill Long
Date Posted: 23 Aug 2013 at 7:56am
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EagleTDL, You have received some excellent input from our renowned electrical expert SteveNJ. The early B tractors that I remember did not - as Steve Says - have any electrical wiring with the exception of the plug wires. In fact, to my recollection there was a kill clip mounted on the mag to stop the tractor. I was not aware of the feature whereby one could move the throttle beyond the running position to kill the engine. I remember I would move to the side of the B and push the kill clip. Later, as you have seen, since nobody wanted to get off the tractor some rigged an off switch such as yours so they did not have to get off the tractor to stop the engine. In fact they usually stopped them on an incline so they could be moved forward to turn the engine without having to crank it. Charlie, I do not remember any B tractors coming through with the WICO mags as original equipment. Take good care of my favorite. You have a collector's tractor. During WWII a few B tractors were made without electrics to save the copper for the war effort. The starter hole in the torque tube was plugged with a cover and there was a small triangle tin to fill the gap where the tool box was cut for the battery box. The bosses for the battery and generator were there but not used. After the war when these items were readily available they were usually added and the plug and the triangle were junked. Finding one of these would be very significant. Sorry I talked so long but you just seemed to catch on an interesting subject. Remember, the B was a very BASIC unit. Good Luck! Bill Long |
Posted By: EagleTDL
Date Posted: 23 Aug 2013 at 8:25am
No problem Bill! You guys are a wealth of information and have been a huge help to me, and I'm still in the "tear down and inspect" mode on my B. No telling what help I'll need once I try to get this thing running! And Yes Sir, that's my typical MO, asking all the strange questions...  I've got some plans for this ol' gal, but that will come in time...
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Posted By: BrianC
Date Posted: 23 Aug 2013 at 9:37am
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My C has had the original Fairbanks Morse, an American Bosch and now a Wico magneto. The Wico looks like yours shown in picture. Question, were there any other brands that would fit ?
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Posted By: CTuckerNWIL
Date Posted: 23 Aug 2013 at 10:05am
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My 38 B has a toggle switch on top of the toolbox. The wire goes thru the toolbox and out along the right side of the block.
------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: EagleTDL
Date Posted: 23 Aug 2013 at 10:33am
I think that will be my option Mr Tuck... Glad to know I won't be the only one running a similiar setup! All future questions will come to you...
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Posted By: Steve in NJ
Date Posted: 23 Aug 2013 at 2:41pm
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As with any mass produced vehicle, (Tractors included) AC always had a back-up vendor just in case the main vender suppling particular parts ran behind in supply. Wico was the backup vendor, and they did use the "X" series flange mount Magneto. Although, they were scarce, on a lot of AC's, they were used from what I've read when I first started doing research when I bought my B. I even serviced a few customer Wico's, and those customer's told me that was the Mag that came on the Tractor new. That sorta' varified what I read. Those flange mount style Mags did come on other brands of Tractors. The lag angle was different on some of those Mags because they were made specifically for certain brands of Tractors. The Fairbanks FMJ4B3 was built specifically for AC. The "3" was the number for the vendor that Fairbanks made the Magneto for.
FMJ4B3- FM= Fairbanks/Morse "J"= series or model Magneto 4= 4 cylinder engine B= flange mount "3"= vendor- Allis Chalmers. If the Mag had an "A" on the end of the "3" the grounding lug was located on the engine block side. (WC's with rod actuated Kill)
mailto:Steve@B&B" rel="nofollow - Steve@B&B
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Posted By: EagleTDL
Date Posted: 23 Aug 2013 at 5:00pm
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Steve, you are a veritable cornucopia of information! LOL Thanks for the info! Don't know if I understand it all, but thanks nonetheless...
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Posted By: Steve in NJ
Date Posted: 25 Aug 2013 at 10:18am
| Just enjoy helping people out when I can dat's all..... |
Posted By: HemiEd
Date Posted: 06 May 2017 at 12:12pm
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Hello, I have been working on my Dad's old 48 C after inheriting it three years ago. It was pretty much apart, but Dad had rebuilt the engine probably 20 years ago. I purchased a wiring harness from Steiner tractor and had decided it was time to get the old girl moving. I actually drove it up and parked this morning! My question, related to this thread is that the ground on the mag does not kill the motor when it is running. You can push the ground tab on the mag, or ground the wire, nothing, it just keeps on running. Can someone help me with this please?
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Posted By: CTuckerNWIL
Date Posted: 06 May 2017 at 5:19pm
I would guess that the wire is not connected inside the mag, so it's not getting shorted out to kill the fire. ------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: Steve in NJ
Date Posted: 06 May 2017 at 7:17pm
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I'm wit' Tuck on that one. There's an insulated wire that is connected to the inside of the screw that comes out to hold the shut-down tang in place. That insulated wire runs under the front of the coil inside the unit and up to the points. Doesn't sound like its there or connected as Tuck mentioned. No wire... no shut off.....Might havta' pull the choke closed to shut down the engine till ya git' the wire connected. HTH Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |