Farmall cub 12v conversion

Gillou · Dec 6, 2008

are there things to change/adapt when you put a 12v battery?

Anonymous-0 · Dec 6, 2008

If you want to convert for more cranking power, in my opinion it's not necessary. The same 6 Volt battery used on the Cub is used on most other IH tractors through the H. The weakest part of the system is the charging system.
To convert to 12 volt you will need to change your light bulbs and install a coil resistor such as the RU4. You will change from a "+" ground system to a "-" ground. This means you will need to swap the wires on the coil. Connect the ignition in series with the RU4 resistor to the "+" coil terminal and the distributor to the "-" terminal. If you have a magneto, no changes need to be made to the ignition system. If you have the bayonet type 1133 bulbs replacement them with 1143 bulbs. For reliable charging install a internally regulated alternator such as the Delco 10SI. If you would choose a 1-wire alternator, get one with a low turn-on regulator.
K-Mo

John T · Dec 6, 2008

Unless the starter is shot or theres a battery or cable or switch problem or the engines in poor shape, theres no reason why a lil cub shouldnt start just fine at 6 volts even in extreme cold temps (plus that keeps it all original versus cobbled or jury rigged) . Heck even a much harder to crank H can start at 6 volts. I can understand a conversion maybe for an M in extreme cold climates but a C shouldnt be any problem at 6 volts. If the Cub has a good heavy duty battery and 0 gauge battery n starter n ground cables (NOT wimpy 4 gauge automotive) it ought to crank over plenty fast.

HOWEVER its your tractor and your choice and if you insist on converting,,,,,,,,if its a coil ignition EITHER add an external voltage dropping (12 to 6) Ballast Resistor OR ELSE use a full true 12 volt coil no ballast rerquired (no change if a mag),,,,,,,,change light bulbs to 12 volt,,,,,,,,,convert charging system to 12 volt,,,,,,,,if you use an alternator most are neg ground so that requires polarity swap (coil leads and if it has an ammeter those leads need swapped also)

John T

Gillou · Dec 31, 2008

many thanks my friend !

Gillou · Dec 31, 2008

thank you my dear K-Mo and happy new year !

mkirsch · Dec 31, 2008

Gillou, unless the electrical system is missing, you are much better off fixing the 6V system you have now. Often simply cleaning the battery connections on both ends will fix the problem. Cubs don't need all that much power to turn their tiny engines over. John T has an excellent troubleshooting guide for the generator system that he posts from time to time.

Farmall cub 12v conversion

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