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HenryO

Member
I am still working on my Farmall A (1943) . It runs for about 45 mins and then stops. Mag is so hot it is hard to touch. SOO as suggested I am going to add a regular coil and rewire it as previously suggested. Question--------do I use a 6 colt coil or an internally ressisted 12 volt coil? Question--- I believe I will need a on off switch ( 2 pole) instead of the single pole now on it Thanks for the answers Henry
 
If it is still 6v, you can use a six v coil. There is no commonly used coil with a internal resistor. A 12v coil for use with a external resistor is a close approximation of a 6v coil. So either could be used. The original switch is one pole because it is a grounding switch that stops the tractor by grounding the coil primary. You will need a two pole on off switch, or an original switch for a coil ignition. (this site has them). connect it to the load side of the amp gauge. Jim
 
Well if it is a 12 volt set up yes use a 12 volt coil that says no external resister needed. The it no resister built in to it but it is just made to work on 12 volt by the way it is wound. Of course if it is still 6 volts use a 6 volt coil
 
I agree with professor Jim, if its a 6 volt tractor use a 6 volt coil, but if its a 12 volt use a full true 12 volt coil no external ballast required makes things so much easier and simpler. If you're just using the old mags points as the method to switch coil current on and off that works okay other then theres no variable RPM based timing advance like a true coil distributor ignition uses. The ignition switch is used to supply hot battery voltage to the coils input when ON but none when off, piece of cake.

John T
 
well i am kinda lost... i have never seen a factory tractor with a magneto running 12 volts. all i have ever seen is a 6 volt battery with magnetos if they had a battery. as that was the idea of a magneto to eliminate a battery. so how do u know what coil goes with a magneto? i have a super m here witha mag and it, has a regular coil wired to the mag. i did not even think to look if it was 6 volt or 12 volt. you guys are talking about 6 and 12 volt tractors... so how do you know what coil rating to wire into the magneto??? i sure would not think it would be 12 volts. or are u's talking about battery's? if it has a 12 volt battery to use a 12 volt coil??
 

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