Need Wiring diagram

[staninlowerAL]

Wire goes from ign. sw to magneto, I do not have external coil, there is a post on the magneto so something goes to it.

Glen explained it.

Now tractor won't start, probably burned up the magneto's internal coil.

Two solutions; external coil for the magneto or purchase the magneto's internal coil.

Glen and Eugene has you covered. Note especially Glen's statement about 2 completely separate systems. If you decide to repair the magneto and use it for providing electrical power for the ignition then your 12v conversion with the alternator etc. will only recharge the battery, provide electricity for the lights and any other electrical accessories. The magneto with its internal coil works on induction current and is therefore separate from the tractor's other electrical system. That's why you can start with a hand crank and run with the magneto only. On the other hand, if you convert to an external coil you will need a true ignition switch instead of the kill switch for interrupting battery power to the external coil. The kill switch post connection on the magneto then becomes the voltage input point from the external coil. This all is assuming you are switching to external coil and neg ground with your new 12v alternator/battery.

[staninlowerAL]

Yep, I have destroyed the magneto coil. Disconnected wire and still wouldn't start.
Can I assume by mounting http://www.tmtractor.com/new/el/808fp.htm external coil and run a coil wire to distributor with a hot wire from console sw would be one solution. Replacing magneto coil and change out the switch would be the other solution.
What's involved with changing magneto coil and is that the only part I need to replace? Can you provide a link to the correct switch on the TM site?

Depends on your objective. Do you want to run a magneto system like it came OEM or does it matter. If it were my tractor I would (1) get a quality 12v internal resistor coil from an auto parts store and a 2 pole ignition switch (not a kill switch to ground) and follow the wiring diagram that you have which shows the current flow from battery +, to switch, to + side of coil then -side of coil to the post on the magneto. The wire from the internal coil to the points needs to be discarded. You then have a battery ignition system using a magneto in place of the normal distributor. To reduce the cost of future maintenance I would look for a good used distributor (complete with mounting) to replace the magneto housing. Replacing the rotor and pinion gears alone will cost almost as much as a magneto coil. (2)BUT if you want to stay stock OEM like the 1949 came with then buy a magneto coil and go for it.

[rstoots]

Would prefer to stay with the magneto but want to make sure I'm buying the correct parts. Would like some idea on how to replace magneto coil, can you answer those questions?

[staninlowerAL]

My suggestion is to go to "QUICK LINKS" at the top left corner of this page, locate the Service Manual GSS 1012 Electrical Equipment and print it out. Pages 1-6 will give you complete instructions on service and maintenance of a J4 magneto. You can replace the coil by removing the mag from the tractor. Follow the instructions. If you want to do a complete service and repair then you will need the special puller to be able to access the impulse coupling to check/replace the springs and make sure it's all correct. If you've never done this before I suggest you seek out a magneto rebuilder or one of the FORUM members who are expert on this or BRING THE MAGNETO TO A CUBFEST along with the needed rebuild parts. There you will find members who are expert and proficient in rebuilding the magneto. Rick Spivey did one for me at DSCF last year. Check with McDonald Carb for prices, I expect you will spend $200-$300 for parts (coil, rotor/penion, springs, ignition points, condenser, etc) to do a complete rebuild but afterwards it will be as good as new.
EDIT: Sanford NC, mid June. Probably about 4 hours away from Fredricksburg VA

[Glen]

Hi,
Below is the magneto ignition switch that TM Tractor sells, looks like it is the Case IH switch.
Next is a new coil.
Below are pages from the Cub parts manual showing the magneto. You can see how the coil is held in, it has a rectangular bar through it. You have to re use that with the new coil.

http://www.tmtractor.com/new/el/605fp.htm

http://www.tmtractor.com/new/el/713fp.htm

http://www.farmallcub.info/manuals/cub_ ... 012-22.jpg

http://www.farmallcub.info/manuals/cub_ ... 012-23.jpg

[rstoots]

Thank you Glen, you've helped me again. Parts ordered. Looks like an easy repair.

[Glen]

Hi,
I haven't read back through all your posts. I'm not sure if you have a 1 wire Delco alternator. I've never put an alt on a Cub with a magneto. The magneto ignition switch has no 12 volts at it, so no way to power anything from there. Stan probably knows about the wiring, if you need other wires.