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8N Coil

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Otto Bombach

09-24-2006 21:45:38

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Do I need a resistor for a 12 volt coil on an 8N?
I plan to buy a generic 12 volt coil tomorrow.

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Andy Oklahoma

09-25-2006 08:04:19

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Re: 8N Coil in reply to Otto Bombach, 09-24-2006 21:45:38

Yes, you will need a new two prong 12-volt resistor. However, if you will ask the parts man he will tell you there are about three different voltage resistances. off-hand I can't remember what they are. You will have to choose. On my own tractor I found that it didn't seem to make a lot of difference whether or not the resistor was hooked up. Might have been something to do with the lack of regular gas.

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souNdguy

09-25-2006 06:27:06

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Re: 8N Coil in reply to Otto Bombach, 09-24-2006 21:45:38

In addition to the info Phil gave you, a stock 6v 8n coil and an 8NE10306 resistor will work fine on a 12v system.

Soundguy

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Phil (NJ,AZ,Sask)

09-25-2006 01:53:11

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Re: 8N Coil in reply to Otto Bombach, 09-24-2006 21:45:38

Otto,
I assume this is a side mount, round coil!

That all depends on which 12 volt coil you buy. Some PPL have good luck with NAPA/Echlin IC14 which is a 3 ohm coil that does not need a resistor.

Most other auto coils will need an Ignition Resistor that matches that coil. Examples
Ford Truck 1958-72 Napa/Echlin coil #IC10 and Resistor# ICR22. The Chev Truck 1958-62 Napa/Echlin coil #IC12
and Resistor # ICR13 The OEM 6 Volt coil will work with "Standard Auto Parts" ignition resistor # RU10

Hope this Helps,

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Jim Broughton

09-24-2006 22:24:36

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Re: 8N Coil in reply to Otto Bombach, 09-24-2006 21:45:38

Otto; Yeah, if your system is 12 volt with alternator and NEGATIVE ground.If it's 12V generator and positive ground, you don't need one.As for the coil, the old 8N 6V coil is usually strong enough to work on a 12 V system, so why change if you don't have to? Lots of luck ! Jim B.

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souNdguy

09-25-2006 06:25:15

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Re: 8N Coil in reply to Jim Broughton, 09-24-2006 22:24:36

Wow... bad advice all around.

It makes no difference on a side mount coil what the polarity is, and what the charging system is, as to if a 12v coil is suitable. The round coild can be run positive or negative ground, and alt / genny has no bearing on the issue.

And.. the advice that a 6v round coil works fine on 12v is just plain bad info.

Se the post above from Phil... it has better info.

Soundguy

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Otto Bombach

09-25-2006 06:37:27

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Re: 8N Coil in reply to souNdguy, 09-25-2006 06:25:15

I have a 12 v generator and front mount distributor. The 12 v coil went bad. It was wired so that it bypassed the resistor while cranking. Now I was planning to buy a new 12 v coil and either do away with the resistor entirely, or leave it in the system all the time, eliminating the bypass.

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Phil (NJ,AZ,Sask)

09-25-2006 10:10:52

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Re: 8N Coil in reply to Otto Bombach, 09-25-2006 06:37:27

Otto, If you buy the 2.5 ohm 12 Volt front mount
coil you MAY use a partial bypass function BUT not a total bypass.

The Operating (running), wiring from the Ignition switch: ICR 23, then the OEM Ballast, and then the coil.

Starting (partial Bypass) The I terminal on the starter relay is wired to the Junction of the ICR23 & OEM Ballast. This will bypass only the ICR23.
----- ----- ----- ----- ----- ----- ----- --
If you want to use a 6 volt front mount coil with partial bypass:

Wiring from the Ignition switch: ICR 23, then the OEM Ballast, and then RU-10, and then the coil.

Starting (partial Bypass) The I terminal on the starter relay is wired to the Junction of the ICR23 & OEM Ballast. This will bypass ONLY the ICR23.

Hope This Helps,

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Otto Bombach

09-25-2006 16:22:41

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Re: 8N Coil in reply to Phil (NJ,AZ,Sask), 09-25-2006 10:10:52

I put on the new 12 v 2.4 ohm coil with the original 1.6 ohm resistor and still a weak spark. I retraced my steps and reconnected a condenser that was mounted to the coil insead of in the front mounted distributor. I had disconnected the coil mounted condenser after putting new points and a condenser in the distributor. Now I have a spark again. I will have to wait till I get back from a two week trip to Europe with my daughter before I can try to start it. Could my new condenser have been bad or does it have to be mounted at the coil?

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Phil (NJ,Az,Sask)

09-25-2006 19:02:54

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Re: 8N Coil in reply to Otto Bombach, 09-25-2006 16:22:41

Otto, If I understand your system you have an external coil connected into a front mount distributor. The front mount is only used to switch (points) the coil primary & the Cap is used to distribute Hi-Voltage.

If that is true? yes! things change as the coil you are using wants/needs more than 3 amps.

BTW: If you want to keep working I will take your place on the trip to Europe

Hope this helps,

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souNdguy

09-25-2006 06:47:40

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Re: 8N Coil in reply to Otto Bombach, 09-25-2006 06:37:27

Different beast.

The more info you guys give us.. the better tailored the answers will be.

For the front mount coils.. some people have good luck with running a 12v coil, plus the oem ballast ressitor, or a 12v coil with about 1/2 ohm of resistance in line.

There should really be no need for a bypass. besides.. the oem ballast resistor has a temperature coeficient, and acts as a semi bypass when it is cold.

You can also simply use a 6v coil, oem ballast resistor.. and an 8ne10306 dropping resistor.

(EDIT: for clarity.. on my previous post.. polarity on the side mount coil does matter.. it's just that you can hook it up either way to match positive or negative ground.. unlike a front mount coil.. didn't wan't anyone to misunderstand.. etc.. )

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