Which Coil?

69-3400

Member
How do I determine which coil I need? The tractor is a 1969 3400. Everything is buried where it cannot be inspected. I managed to remove the coil working blind but there isn't any information on it. The parts store asked me if the coil needs an internal resistor. I told him the only thing in the maint manual is 5" and 5.5" coils and that stumped him. Both of his coils appear to be the same size and both are shorter than what came off the tractor. The part number in the parts book came up with a coil that has a resistor mounted to it but with such limited access I don't think it would work and the wire from the key has a strange cover on some of it. Could the resistor be built into the wire? IF that is the case, would it hurt to buy a coil with a built in resistor and replace the hot wire?
 
The wire to the coil is 3 folds of
resistive wire wrapped in a "strange
cover".
It connects with a bullet connector by the
solenoid. From the bullet connector to the
key switch is normal wire.
You can replace that 30" of resistive wire
from the solenoid to the coil and use a 12v
no resister required coil or go with the
resister needed coil.
It's a horse apiece.
 

Thanks, the mice have had their way with this thing so I don't really know what is suppose to be there and what isn't. I think there are 3 different color wires between the key and the coil. That will go away tomorrow. Running new wire will also give me enough length to connect the wires before working blind to install the coil. I am considering the Pertronix ignition conversion as well.
 
If you are thinking of EI someday and
running new wires then eliminate the
resistor wire and go with a full 12v coil
as EI likes full voltage.
That said, though I personally have had
good luck with the Pertronix kit (not
everyone has) I still strongly suggest you
get it running reliably on the old points
system First. Then down the road if you get
tires of messing with points on those
darned 3 cylinder distributers - especially
if you have a loader, then and only then
swap to EI.
 
The loader isn’t helping. The tractor was running great when I parked it last spring but I can’t get it to fire now. I had spark from the coil but not at the plugs. Now I don’t get spark from the coil either. Rotor and cap look fine but The mounting plate for the points and condenser is very loose and has me wondering if I should buy a new distributor.
 
mvphoto27358.jpg

Here is the old coil wire.
mvphoto27359.jpg

I wondered what the tape could be hiding but the wires looked okay. Still going to replace coil and wire on general principle.
 
Ditto what UD said.. EI or no EI, rip out that resistor wire and put in a real native 12v coil like a napa IC14SB, and some 14awg
wire. way less complicated.
 
Only drawback to negating the external resistor or resistor wire and going with a true 12 volt coil is that you cannot achieve the hotter spark during starting that you can with an external resistor and a bypass wire.
 
Good point Sean.
Ford didn't use a bypass though.
I'm pretty sure the original solenoids were
3 post. You could add it of course.
Replacement solenoids are mostly 4 post
now. But originally there was no bypass.
That resister wire essentially went
straight from the key switch, through the
resister wire to the coil.
 

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