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GfdMatt 
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Joined: 28 Jul 2019
Location: Arizona
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 Topic: Model B electrical help please!
Posted: 05 Aug 2019 at 12:29am |
Hello all,
I acquired a Model B not too long ago and have been spending a lot of time going through the tractor only to realize that when the tractor was "restored" about 13 years ago, a lot of things were "changed" during the process.
As the tractor sits, it is still 6v system, with a new generator. It will start via crank or after about 5 or 6 tries on the starter. The lights do work and the switches at the box are functional. A new battery was installed last week along with a new ammeter as well.
One of the issues that I am having is that the switch I would assume is to cut off the magneto to kill the tractor is not functioning like it should- as a matter of fact it will only act as a primary/secondary switch for the lights depending on the order the switches are flipped. There is a small gain on the ammeter when the tractor is running...
As I have been looking at the wiring diagrams, I am finding that the positive battery cable is actually being used as the ground? It is currently set up with a negative ground.
Any help would be a great. I would like to get the tractor as functional as possible, and figuring this piece out would be awesome.
Thanks, Matt
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jaybmiller
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Joined: 12 Sep 2009
Location: Greensville,Ont
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Posted: 05 Aug 2019 at 5:30am |
the boys with Bs will reply soon.... however, as it's still 6 volt, I'd return it back to positive ground, as it was when built. You'll have to reflash the genny(no big deal) and then it would be correct. someone will know about the switch problem. I have to ask , is the wiring 100% new, or does it look 'bodged' ?
Jay
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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
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Sugarmaker
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Posted: 05 Aug 2019 at 7:19am |
Matt, Welcome! Congrats on the B! Step back for a minute and try to decide what you want in the electricals for the tractor. Do you want it factory original or just crank start functional, or new custom wiring upgrade to have a reliable start from the seat? Each of these have some things that will need to be done and some costs. -Most of my stuff I do a custom upgrade and have been real happy with them probably $200. -Fix what you have maybe $100??? -Factory original in every way and fresh maybe $300?? Just my guesses. They will all work. Do you have a mag or distributor? Regards, Chris
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D17 1958 (NFE), WD45 1954 (NFE), WD 1952 (NFE), WD 1950 (WFE), Allis F-40 forklift, Allis CA, Allis D14, Ford Jubilee, Many IH Cub Cadets, 32 Ford Dump, 65 Comet.
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CTuckerNWIL
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Posted: 05 Aug 2019 at 8:09am |
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The "kill switch" for the magneto has nothing to do with the lights. It is a stand alone switch. It should be a normally closed switch, so when you flip it on it is open. When flipped off, it grounds the magneto out and kills the spark. One wire from the switch to the post on the side of the mag and the other side to ground.
Being set up as negative ground has no effect on anything. If you switch it back to Positive ground and don't know how to polarize the generator, you will let the smoke out of the genny and have to find a new one, or get it rebuilt.
If it ain't broke, don't "fix" it.
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Hubert (Ga)engine7
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Posted: 05 Aug 2019 at 8:49am |
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Matt, welcome to the Forum.X2 on what has already been posted. A small gain on the ammeter is good especially if the replacement ammeter is over a 20 amp unit. The original light switch was 3 position, low charge, high charge, and high charge with the lights on. Your new light switch could be just an off/on switch but neither should be connected to the magneto. Ober the years the B's as well as all others have had every wiring "fix" imaginable done to them. Steve at B&B is the guru for all things electrical on these Orange tractors and if he sees this he will chime in. If not just request his contact information on here.
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Just an old country boy saved by the grace of God.
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Gerald J.
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Posted: 05 Aug 2019 at 9:17am |
The battery polarity and the generator polarity must match or the generator life will be very short. The generator polarity is set by flashing the generator as described in the shop manual or the operator's manual. I have a shop manual available at: http://geraldj.networkiowa.com/Trees/Allis-Chalmers-G-B-C-CA-Service.pdf 6 volt AC systems were positive ground when built. Besides the charging, battery polarity affects battery ignition but not magneto ignition. Also can effect the generator voltage regulator if present. Could not be regulated with the three position light switch that leaves generator output setting to the tractor operator. High after starting for a while then backing down on the generator output to prevent overcharging the battery and removing water from the battery electrolyte. Bubbling of the electrolyte is a sign of overcharging as is loss of water. Gerald J.
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GfdMatt
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Posted: 05 Aug 2019 at 12:38pm |
Thank you for all of the replies!
I have taken a few photos and am going to do my best to get them to post on here and not be giant...
When the tractor is running, I am currently getting around 7.5-8 volt charge back on the battery. Does this seem to be appropriate?
Like it was said, it seems like it is just set up for a "positive" start, with the generator recharging the battery.
The pull switch is only an on/off switch. It is not a three-way. I am just wondering at this point why there are two switches wired in? Is one supposed to be allowing the battery to be charged, then?
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HoughMade
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Posted: 05 Aug 2019 at 12:48pm |
Toggle should be the kill switch, the other is the lights.
The kill switch has nothing to do with polarity. A closed switch grounds the magneto and kills the engine. An open switch means the magneto is not grounded and can run. This is the opposite of how we normally think of a light switch with "on" being closed and "off" being open.
Oh, and yours are reversed. The light should be on the left and the kill switch on the right, but that doesn't matter to operation.
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1951 B
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mdm1
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Posted: 05 Aug 2019 at 2:18pm |
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You have a voltage regulator not the factory cut out so you would not have the three way switch. Like said one switch for lights the other shuts the tractor off.
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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!
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GfdMatt
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Posted: 05 Aug 2019 at 3:42pm |
I think we are to something here. Here is the wiring diagram as it currently sits. Any help will be appreciated.
I forgot the labels on the switch box- top white round is the ammeter, the left small black circle is the pull switch and the rectangle is the lever switch.
-Matt
Edited by GfdMatt - 05 Aug 2019 at 3:43pm
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Steve in NJ
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Posted: 05 Aug 2019 at 3:43pm |
As Mike mentioned, your 6V system has been upgraded to a Voltage Regulator. Nothin' wrong with this type of upgrade. It just eliminates the 3 position Headlight/Charging switch. If the engine is running around 600-650 rpm with a slight charge, if the Battery is in good working order (doesn't matter if its new or old) then your 7.5-8.0 volt reading would be normal because there isn't any load on the system, so the VR is just keeping things happy like it should.
As the guys mentioned 6V Pos. Grd is the norm for these Tractors. You could go either way doesn't matter....HTH Steve@B&B
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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife
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Bill Long
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Posted: 05 Aug 2019 at 9:54pm |
GfdMatt, You have received excellent replies from the B experts - especially SteveNJ, he is our in house electrical expert. Interesting to me to see the numerous changes that have been made from the original B set up. I can see you have things well in hand. Take good care of my Favorite Allis Chalmers Tractor - the B Good Luck! Bill Long
ps: Outstanding pictures
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GfdMatt
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Posted: 05 Aug 2019 at 11:40pm |
Gents, I appreciate all of the insightful knowledge that you have thrown my way. Everything is really making much more sense now.
Does anyone have experience with this Fairbanks morse type of magneto? I was looking for a ground post and couldn't see one. I am guessing that maybe it's on the motor side of the housing?
I would like to wire in a switch to cut the motor.
For kicks, here are some shots of the tractor.
Thank you all again, Matt
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mdm1
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Posted: 06 Aug 2019 at 4:58am |
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I thought you had a shut off switch. How do you shut it off now? My B's have a stud on the outside of the mag cover that my kill switch is wired to.
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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!
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HoughMade
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Posted: 06 Aug 2019 at 7:03am |
On the original magneto, there should be an isolated bolt on the outside of the mag to attach the kill wire. I see that your does not have this so it may not be original, but I would think it would have a contact for the kill switch somewhere, even if it was originally made for another application. I blew up this pic to show where the kill switch wire connects on mine which I believe to be as original (this is a rebuilt magneto, but the housing on my original magneto was the same). You can see the small (#10) bolt coming out of the magneto housing just behind the governor. I routed the kill wire around the front of the engine so it joins the rest of the wiring harness on the left side. 
Edited by HoughMade - 06 Aug 2019 at 7:08am
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1951 B
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Steve in NJ
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Posted: 06 Aug 2019 at 7:22am |
Matt, That is a "K" series F/M Magneto. (FMK 4, FMK 4B) The ground tab on that particular Mag is up front through the Mag cap. In the closeup pic of the Mag, it doesn't look like its there. The pic is dark but there should be a hole up in the Mag cover. It should be on the lower end of the Mag cap toward the ground side. The grounding tag is shaped like a candy cane and there's 3 pieces to it. If you have an empty hole there, that's where the grounding tang goes. We carry them in stock. If you visit our website and look under "single cap Magneto" you'll see what it looks like. Steve@B&B
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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife
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Steve in NJ
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Posted: 06 Aug 2019 at 7:36am |
Jim has a "J" series Mag. Different from the earlier "K" series Mag that your B is equipped with. The "J" Mag replaced the "K" Mag. The "K" Mag is a one piece cap design with larger housing, (which you have) the "J" series Mag is a two piece lower cover and upper cap design with a smaller housing. (FMJ4B3) If you want to learn a little basics on the different Magneto's and what the numbers and digits mean, my website has information explaining the different Mags that came on the AC machines through the years. The model "J" that came on the early WC's & Speed Patrols had the FMJ4B3 "A". That particular "J" model with the "A" at the end had the grounding tab to the engine side because those particular early Tractors had a rod connected the the tab to shut the engine down. The model "X" Magneto (FMX4B3) replaced the "J" series Mag just before Battery Ignition started to become the standard. The "X" series Mag was the best of the bunch, and Fairbanks pretty much had all the quirks taken out from the "J" series by that time. HTH. Steve@B&B
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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife
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Gerald J.
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Posted: 06 Aug 2019 at 9:23am |
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Basically the points in the magneto when they open cause ignition to the plug connected through the rotor in the magneto. One side of the points is grounded. The external kill switch grounds the ungrounded point to prevent ignition and so shuts the engine down. Some magneto installations included a push button on the magneto, most brought the ungrounded point connection out to a screw post so a wire could run to a panel mounted kill switch. If the kill switch is a toggle switch, not a spring loaded push button or lever switch you have to remember to move the kill switch from the kill position to get the engine to start. With the kill switch in the kill position there is no amount of cranking (hours or days) that will start the engine.
Gerald J.
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Steve in NJ
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Posted: 06 Aug 2019 at 9:49am |
I happen to notice that push/pull switch in your instrument box is an excellent two terminal 75amp rated push/pull from Cole/Hersee. We're a C/H dealer and keep those high amp switches in stock as well. Just happen to notice that.... Steve@B&B
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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife
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