Coil getting hot

Abbby

Member
Working on getting my 1963 4000 gas running. Did a 12 volt conversion and rewired all. Using a 12 volt coil with internal resistor. Noticed when I was trying to get the tractor running the coil got pretty hot. I was checking spark at coil wire and plug wires and it was definitely good. Ouch. Should I be using one with an external resistor? I have the coil and resistor on the bench but just thought be better to have less things that could go wrong.
 
(quoted from post at 11:24:01 08/24/14) Working on getting my 1963 4000 gas running. Did a 12 volt conversion and rewired all. Using a 12 volt coil with internal resistor. Noticed when I was trying to get the tractor running the coil got pretty hot. I was checking spark at coil wire and plug wires and it was definitely good. Ouch. Should I be using one with an external resistor? I have the coil and resistor on the bench but just thought be better to have less things that could go wrong.
ot unusual for coil to approach 200 degrees and that will feel very hot to most hands.
 
If you leave the key turn on and the points are closed the coil is going to get hot. Don't worry about it. Just make a habit of turning off the key because you can easily burn out your points this way.
 
Found it on Ebay for $16.
"D5TE12029AB Ford / New Holland Internal Resistor Ignition Coil 6 Volt to 12 Volt"
Not sure of resistance. Tested voltage on neg side and it showed about .6. Seems strange. Pretty darn good zap though. Got me a few times.
 
"Internal Resistor Ignition Coil 6 Volt to 12 Volt" doesn't make any sense.

First off, coils may have an internal resistance, but they do not have an internal resistor.

Coils that are designed for a 6 volt system and no external resistor require an external resistor when installed into a 12 volt system.

Coils that are designed for a 12 volt system and no external resistor normally do not perform well, if at all, in a 6 volt system.
 
Sorry to get everyone all worked up. So are you suggesting the coil I have will work fine? 12 volt converted tractor. Seems to have good spark but have not ran yet due to doing carb rebuild. When trying to start I had gas coming out all over. Float stuck. Thanks for all the info.
 
If you are reading six tenths of a volt from the distributor side of the coil to ground, that means you're getting six tenths of a volt drop across the points. I'll bet you can get that number down to a couple of tenths if you file your points a bit.
 
OK. So rest of the story. 12 volt neg ground. Rebuilt the carb and it fired right up and ran for about 5 seconds and shut off. No spark at plugs or coil wire. I have an external resistor coil with resistor so hooked up. Now voltage at coil is about 4.5 on plus side and .6 on neg side of coil. still no spark. Is this the right voltage and do you think I smoked the resistor. I will take off cap tomorrow and make sure points are still opening.
 
(quoted from post at 21:58:18 08/28/14) OK. So rest of the story. 12 volt neg ground. Rebuilt the carb and it fired right up and ran for about 5 seconds and shut off. No spark at plugs or coil wire. I have an external resistor coil with resistor so hooked up. Now voltage at coil is about 4.5 on plus side and .6 on neg side of coil. still no spark. Is this the right voltage and do you think I smoked the resistor. I will take off cap tomorrow and make sure points are still opening.

4.5v.........is this right? You never did answer the question as to what is primary resistance of the coil, so no one can properly answer that question as to 4.5v or not. Voltage is the indirect way to arrive at an answer, anyway. What you are really looking for is a steady state primary current of 3.5 to 4amperes. Select resistor to obtain that amperage.
 

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