1952 Model B wiring question
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    1952 Model B wiring question

    Hello,

    New to site and ownership. Just picked up a 1952 Model B. It appears to be a magneto powered model (XH number on case). I have a loose wire dangling from the ignition switch and cannot find where it goes????? The other ignition switch wire is connected to the front of the tractor to what I'm guessing is the alternator/generator???? Lastly, anyone have the wiring diagram for this set up?

    Thanks for the help!!

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    Welcome to GTT
    Are you aware that you can view the parts schematic online at JD Parts? Below is a photo that might help you.
    Attached Thumbnails Attached Thumbnails Capture.PNG  
    DRobinson and dieselshadow like this.

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    csprngman1 (12-02-2018)

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    Dan in Ohio's Avatar
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    That dangling wire would go to the coil on my 1950 B but mine has a delco remy distributor not a mag. BTW this is a little off topic but does your B have a water pump. I check everyone I see and have only ever seen one. Posted that somewhere recently and of course everyone and there BIL has at least two of them . So if yours has a water pump please post a pic or it did not happen. Thanks
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    Dan,

    Mine does not have a water pump; according to the owners manual it is a siphon system-assuming that as the water warms it rises and produces a flow. As far as the dangling wire goes, I'm guessing that yes, it would go to a coil. Mine clearly has a magneto so I'm assuming the best thing to do is just by pass the switch altogether??-any thoughts anyone? The thing cranks regardless of the switch position anyway and I can't think of where I would wire the switch for it to actually operate as an ignition switch...........I don't know if this one originally came with a distributor and thus an ignition switch or if it came with a mag and someone converted it to a distributor and added a switch and has since now gone back to a mag set up?????

    Another question for the group; I've read that these came as 6 volt positive ground. Is it common to convert to negative ground? Mine appears to be wired that way (negative ground) in that the positive cable is connected to the starter and the negative goes straight to a bolt on the chassis in the battery box.

    I've since obtained a new battery and am able to get the engine to turn over, but no signs of life. I am getting spark to the spark plugs so maybe I need to tinker with the carb. Any suggestions greatly appreciated.

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    In the real world it really makes little difference if your JD B battery is attached + or - ground.

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    Back in the era of 6 volt systems it was common to use positive to ground. Many cars, trucks, and tractors, but probably not all, were wired this way. Once you get it running and confirm the wiring harness is good and hooked up properly, you may find the generator/regulator may need to be polarized to assure the battery is getting charged correctly. The starter doesn't care, it will turn one direction only. You will need help from someone better educated in electrical systems than I to explain further.

    Since it is not running yet, I would urge you to buy a service manual that covers your late model B tractor. Check out the one offered by http://www.davenporttractor. com. It is priced reasonably, with clear images, and an authorized reprint.

    You should also check the dangling wire for voltage with the switch on and off. If it did power a distributor in the past, and still has voltage, be sure to tape it up or otherwise insulate it to avoid possible short to ground. If it does not have voltage but does lead to ground with the switch in the off position only, it can be used to ground the magneto to stop the engine. Some magnetos have a post in the front that is insulated from the case but wired to ground the points when the post is grounded. There are kits to add to mags that also provide a button to ground the post directly to the mag case. My Dad added a keyswitch to his '49 B that was used to "kill" the mag spark. It had no other function other than, with the key removed in the off position, it would not start. (Unless you were smart enough to unhook it at the mag. lol) We preferred this to using only the throttle completely closed to starve the engine of fuel and air.
    I will snap a picture of our mag on a '50 B and post it later. Pictures explain things better than I can.

    Have fun with the new Deere!

    tommyhawk
    Last edited by tommyhawk; 12-09-2018 at 09:09 AM.

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    Pictures of magneto ground post and push-pull switch added to the '50 B. Looking for a more permanent switch. This one works backwards of the way I want it to and has proven to be not good enough for the long haul. This mounting place does let one turn off the tractor without leaving the seat. Not OEM but kinda nice in an emergency situation.

    Click image for larger version. 

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    tommyhawk

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    Tommyhawk and Tx Jim, thanks again for the responses. I was able to get it started and surprisingly it ran very well. I removed the carb, took it apart, cleaned it out as best as possible and replaced it without any new parts. Fired up immediately.

    As far as the electrical, the dangling wire from the ignition did spark when touched to ground before I took the ignition switch out of the circuit. The magneto I have does NOT have a grounding post as is pictured with yours Tommyhawk-so I think I'll just leave it inoperable for now....... Not sure yet if the generator is working or not as I did not run it for long and I none of the gauges (except oil pressure which did come alive) seem to work.

    As far as polarization goes, I've read that it should be done before one disconnects the battery, and I've read that it should be done after one connects a battery but before a start attempt. Seems that it makes sense to do it after connecting the battery and before starting. Any advice on this?

    Another ?, if it is wired up negative ground, does it matter which wire gets connected to the battery terminal on the voltage regulator, or any other wire connections on the generator/regulator?

    As usual, I plead ignorance and welcome all advice.

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    Been thinking about some of your questions about the possible differences for wiring, polarization, etc. Why not just switch it back to positive ground? Then any checks and testing procedures in the manual, or advice given by the electrical guys can be followed without doubts about whether will it work or not. It's your tractor, your decision.

    I was looking in the parts book to see if there was a different wiring harness listed for the battery ignition (distributor/coil) type verses the magneto models. Only one listed, no keyswitch.
    To my surprize the distributor shown in the parts manual was a Wico model XD-100, which looks very much like the Wico XH model mag. The XD shows what appears to be a small removable plate on the front side that is listed as a ballast resister. It has an external connection lug for the "dangling wire" from the keyswitch. The coil is internal like the mag. Keyswitch and extra wire is listed with this part.

    The few A's and B's I have seen with distributors were equipped with the Delco-Remy model and an external coil. Maybe I have seen the Wico type at tractor shows and didn't recognize it!

    Polarizing is done with the battery connected, engine not running. Usually replacing a dead battery with a new one does not require a redo. Changing the battery polarity would, i think, and the ammeter may be showing discharge. Other testing (output) of the generator and regulator is mostly done with the engine running. Does the ammeter show discharge now with only the headlights on? Does it do anything different with the engine running and the lights on? Do you have a good starter, generator repair shop that can test the generator and regulator for you?

    tommyhawk

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    Might not be a bad idea to switch back to pos ground..............we'll see as I dig deeper into this thing. As far as the mag goes, there is no post nor any access plate, so I think that this was replaced at some point.......

    I did check the ammeter when turning on the lights and notice that it did swing slightly, but to the positive side; maybe the ammeter is still wired for pos ground?????

    I also tested the generator with the regulator removed and got it to turn as a motor but it looked like a sick old man getting out of bed.............it did read voltage just over 5v; however, when I removed the negative, instead of the motor increasing speed (as per you tube so don't hold me to that), it either stopped or turned at very, very low RPMs until I removed the positive voltage. I also dug into the regulator, cleaned up the points and connections but noticed that there is what I believe is a "spring" type resistor along the length of the bottom of the regulator (exterior) that is connected to the F terminal on the front and a grounding strap on the back...............wasn't able to get any reading on the ohm meter after cleaning off good contact points between and F and back side of resistor or grounding strap, so thinking that this might need replacing along with a generator rebuild.....................I do have a resource for testing so I may chase that down before I tackle myself. Thanks again for the insight and suggestions.

    Before signing off...........anyone have some suggestions for online parts??

    Thanks

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