Resistive Coil Wire ?

Resistive Coil Wire ?

tvince

Jeeper
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Location
KC MO
Vehicle(s)
1978 CJ7
Initial problem, After up to 30 mins after running it would start missing and eventually would not idle, I found that the coil output was the cause by hooking up my timing light to the coil wire and it definatly was missing beats.
So after replacing my ign module, coil, and ign switch..... I started watching the + coil connector and it was reading around 10V and slowly dropping until it got to around 9.5V and missing like crazy. Come to find out that the Resistive coil supply wire was increasing in resistance as it ran for a while.
I am running an excel coil (12V) The Teamrush ign mod, stock ign module on the 78 CJ7 258
My ? is Do I need to keep the Res wire and or a resistor in line with the coil to keep from damaging something
I have it rigged now with a new 10 ga, wire and a 1 ohm 25 watt resistor
and runs fine with 11V at +coil conector. But am I loosing spark potential by limiting Volts and current to the coil.
Or is it necessary to protect ign module
Thanks
Tvince
 
Last edited:
You ask if it is necessary to keep a resistor in line with the coil. The answer is maybe. It depends on the coil. It used to be that all cars needed a resistor in line with the coil. That is because the coil actually has very low resistance and can be damaged if it does not have a resistor in line with it. Then they started to add internal resistance to the coil so you wouldn't have to add your own resistor.
To find out the answer to your question you will have to go back to the manufacturer of your coil (Excel). Look over the documentation that came with the coil or go on their web site. They make several coils so make sure you look up the coil you have installed. They will be able to tell you if you need a resistor.
My MSD coil (and other "performance coils) need a resistor. If the manufacturer recommends a resistor and you don't use one it will still work but the coil will fail much sooner than if you used a resistor. The resistor protects the coil from excessive electrical current.
 
Last edited:
Thanks
went to website they want a ,75 to ,85 ohm resistor in line with the Accel 8140
Thanks for the response / explanation / reason for resistance
Tvince
 

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