Coil for use in 12 volt conversion on Ford 641

fisheron

New User
I purchased a 12 volt conversion kit and received a IDR0001 12 volt coil in the kit. In looking on the internet, I see information saying this coil "has no internal resistor". I've spoken with the seller and he indicates it has the correct internal resistance for a 12 volt conversion. The only markings on the coil are the + and - at the terminals. Are any of you familiar with this IDR0001 coil and know whether this can be used correctly without an external resistor?
 
(quoted from post at 13:24:57 08/17/15) I purchased a 12 volt conversion kit and received a IDR0001 12 volt coil in the kit. In looking on the internet, I see information saying this coil "has no internal resistor". I've spoken with the seller and he indicates it has the correct internal resistance for a 12 volt conversion. The only markings on the coil are the + and - at the terminals. Are any of you familiar with this IDR0001 coil and know whether this can be used correctly without an external resistor?
onnect an Ohmmeter to the = & - terminals. If you read around 3 Ohms use it. If it reads around half that, then you need a resistor. Don't know that part number.
 
everything I find on the internet for that number says:

No Internal Resistor; Addl Info: Used w/External Resistor
New Aftermarket Ignition Coil for Tractor and Agricultural Equipment, it has no internal resistor and is used with an external resistor. Replaces these Part Numbers: Case International 353875R91, 395331R91, 395331R92, 396547R93/ Delco 1115022, 1115043/ Ford D8JL-12029-A/ Massey Ferguson 189673M92, 189673V2.

sounds like a 6v coil to me!
 
Thanks, JMOR,

I'm getting the overrange ohm measurement displayed on the digital voltmeter indicating infinite resistance across the + and - terminals of the coil. Does this mean the coil is bad?
 
assuming you are measuring the coil setting on your bench, and not inthe tractor with the key on.. then I'd guess you are using your meter incorrectly!

one lead to each side.

make sure you are on an ohms setting. make sure your meter does not make you switch one of your leads to a different location for certain measurements ( usually not an issue with volt/ohm.. but... )
 
Thanks, gents,

I'm getting consistent ohm readings of 1.5 ohms now. I can't explain what is different now but it sure looks like a 6 volt coil
 
(quoted from post at 15:58:09 08/17/15) Thanks, gents,

I'm getting consistent ohm readings of 1.5 ohms now. I can't explain what is different now but it sure looks like a 6 volt coil
ure enough!
 
Yup.. 6v coil as I suggested.

If the person selling that in a 12v kit is not supplying a resistor, they are an idiot..
 
There are no coils that I am aware of the have an internal resistor. They all have some amount of internal resistance due to the type and gauge of wire used and the number of windings in the primary, but there is no resistor inside of them. As others have said, 3 ohms or so is the proper internal resistance for a coil that is to be used in a 12 volt system without an external resistor in the circuit. 1.5 ohms or so is the proper internal resistance for a coil that is to be used with a 6 volt system, and it can also be used in a 12 volt system with an external resistor in the circuit.
 
Thanks, all,

I picked up a NAPA IC14SB for ~$22 and confirmed its internal resistance at 3.5 ohms. I won't be using the IDR0001 since it is better suited for 6 volt or 12 volt with external resistor.
 

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