Coil question

[perrycomo]

If I use a 12v coil with internal resistor can I leave the external resistor in place. If not, why not? Just curious. I can remove it if necessary but have to remove the tin to do so, kind of a pain. It's on a '63 4000 (4cyl) gas.

 

[JMOR]

No stock resistor on that tractor and no telling the value of whatever someone added. If small enough, as on 8Ns, it will be fine, but if 1.5 Ohms & up, probably hard start/weak spark. Trial & error is likely your answer. And just FYI, current day coils don't have internal resistor, they are just wound with small enough gauge wire to yield desired resistance.

 

[perrycomo]

Thanks for the reply. The ER is one I put on as part of a 12v conversion kit about 20 years ago. Not sure what ohms it is. So I guess just try it and if it doesn't work too good I'll go ahead and remove the ER. From what I read it sounds like the ER is just another thing to go wrong anyway, so probably best to just get rid of it I guess.

 

[Sean in PA]

No need to physically remove it. Just run a new wire to bypass it.

 

[perrycomo]

Ok, thanks. What are the two connection points? I don't know off hand and it's not in front of me right now.

 

[Sean in PA]

I'm not sure since you converted it to 12 volts and ran the wire for the external resistor yourself. I would assume that it would go from the switched side of the terminal block on the steering column directly to the coil, but if you didn't use that terminal block when you rewired it for 12 volts, I can't be sure.

 

[perrycomo]

Ok, thanks.

 

[Sean in PA]

I just had another thought. If you can reach the wires on the resistor without removing the tin, you could just disconnect them from both sides of the resistor and connect them to each other. Use a wire nut or wrap the connection in electrical tape or heat shrink tubing.

 

[perrycomo]

Yeah, I looked at that. It would be kind of tough but I might be able to do it. Would definitely be the easiest fix.

 

[used red MN]

I just had another thought. If you can reach the wires on the resistor without removing the tin, you could just disconnect them from both sides of the resistor and connect them to each other. Use a wire nut or wrap the connection in electrical tape or heat shrink tubing.

Or you could just use one end or the other of the resistor as a terminal block. Such as put both wires on the screw of either end. It does provide the possibility of an extra location for a short but it would be no different in terms of “odds of it happening” then if you were using the resistor as intended as you have since you did the conversion apparently 20 years ago. My question is why the change? I like the mantra “if it isn’t broke why fix it?

 

[Tom in Mo.]

I would try it first as is.

 

[perrycomo]

Or you could just use one end or the other of the resistor as a terminal block. Such as put both wires on the screw of either end. It does provide the possibility of an extra location for a short but it would be no different in terms of “odds of it happening” then if you were using the resistor as intended as you have since you did the conversion apparently 20 years ago. My question is why the change? I like the mantra “if it isn’t broke why fix it?

I'm having the "runs rough after 30 mins or so" issue. Seems to be getting enough fuel. Thought I'd try replacing the coil first. I know, not the way to do it, but I'm not real good with electrical issues. So, cheap enough to give it a try.