coil

[teebeau69]

I have a '62 ford 4000 and it's been converted over to 12v. It has external resistor and i just got a 12v coil for it and it says to use without external resistor? do i have to get different coil or do i take external resistor off?

 

[sunbeam]

Remove the resister unless you have resister bypass start system then I would get a different coil.

 

[Keith Williams]

teebeau69,
No and Yes.
If you want to keep the external resister, then go get a different coil.
If you want to use this coil, then remove the external resister.
You know what to do now, right!
HTH
Keith

 

[old]

Well your new coil flat out say what to do it says NO external resister so take the resister off. But if you have a start system that by passes the resister when starting not a good idea to use the 12 volt coil no external resister needed because it will not work correctly

 

[souNdguy]

seems the facts and instructions are pretty clear.

you kNOW you have a resistor.

you KNOW the coil tells you to run WITHOUT a resistor.

what do you think should happen at this point given these circumstances and facts?

 

[Royse]

(quoted from post at 14:01:00 01/25/14) Remove the resister unless you have resister bypass start system then I would get a different coil.

How would the resistor bypass system make a difference?
My understanding is they just put 12V to the coil, bypassing the
resistor during starting, then put the resistor back in for running.
With a coil designed to run on 12V, why would it matter?

 

[Indiana Ken]

If the system is wired for a resistor, the starter relay will switch over to the resistor after the starter stops. If you remove the resistor then the coil does not get power and the engine stops. So, it does not matter....but you need to change the wiring such that the coil receives power after the starting operation is complete.

 

[Sean in PA]

The resistor bypass is only for bypassing the resistor when starting, which should only be needed if something else in the electrical system is marginal, like the starter has some windings shorted which would draw the battery voltage down more than normal during starting, or the battery itself being marginal, which would cause the battery voltage to be drawn down too much during starting, or old and worn plugs or plug wires that might need the extra juice form a bypass. If everything in the electrical system is optimal, then a resistor bypass is not needed.

It is only when someone had a problem with starting on a 12 volt system that they added a resistor bypass themselves. The factory systems never had a resistor bypass. The original 6 volt systems did not even have a resistor, and the later 3 cylinder 12 volt systems had a resistor wire from the factory, but they did not come with a resistor bypass.

 

[sunbeam]

When cranking the extra load of the starter drops the voltage in the system. So they use a lower voltage coil and a external resister to drop the voltage when running. So by bypassing the resister when starting the coil sees close to it's operating voltage.

 

[Royse]

Yep, that's my understanding too.
So if you were to switch to a true 12V coil, i.e. no external resistor
required, take the resistor out and connect the wires where it was,
it would make no difference if it it had a bypass or not.
It would run on the correct 12V when bypassed or when not.

 

[sunbeam]

If your system has only one wire going to the resister side of the coil or the coil side of the resister you do not have a bypass setup. If you have 2 you do.