ignition coil labeling

The coil on our right measures 1.2 OHMs. The coil on our left measures 1.4 OHMs so they are both six volt coils in my book. Why are they labeled different. Just because or? The coil on our right was on a Deere 60 I posted about on the Deere forum. The 60 is 12V with no resistor or bypass wire in the ignition feed so it needs a 12 V coil with resistance I will call it but it had this 6V coil on it so the points burned. I thought I had a 12V coil laying around to replace this 6V but I don't so tomorrow I make a trip to town.

On a side note I just put new points supplied by Deere in this tractor and I have never had to do so much bending and adjusting to get the points to open when they hit the cam and then to get the face of the points to hit flat together.

just get a NAPA IC-14SB coil which is 12v no external resistor required. It will be 3 Ohms.

Look what's printed on them, the coil on the left is marked as a 12 Volt coil that needs to be paired with a resistor. The coil on the right is marked 6 Volt.

What part of that is confusing you?

Just different wording from a different
time and place. Chrysler used the
ceramic firewall resistor a couple
decades longer than anyone else and they
wanted to make sure you knew that. Ford
and GM didn't always bother to label
theirs and it led to goofs. Coil on the
right is a more modern universal unit.

Mornin fixer, thanks for the pics and information and I agree with your thinking

As I have posted on here for over twenty years and your data and pictures show:

A coil labeled something like 12 Volts for use with (or requires) external ballast resistor is in reality more like a 6
volt coil and requires the ballast JUST LIKE IT SAYS or it will overheat and the points burn rapidly........

Why labeled different ?? have to ask the manufacturer and the companies that specified and used the coils I guess, I have
no inside info on that..

I bought some points at Big Box Store like Rural King or TSC and another at NAPA and the NAPA were night and day much much
better design and quality

Best wishes

God Bless America please keep her free from socialism

John T

Have you ever wasted a half an hour trying to explain to someone with limited knowledge why their 12 volt vehicle requires a 6 volt coil?

This may help to understand why the Mopar coil is labeled the way it is.

Simple. Use either coil on 6 volts with no resistor. Use either coil on 12 volts with resistor. Simple.

Have you ever wasted a half an hour trying to explain to someone with limited knowledge why their 12 volt vehicle requires a
6 volt coil?

Great question and the answer is YES I HAVE many many times over 20 years on here lol it can get frustrating but hey Im here
to help the best I can and will continue to do so, just how I was raised and who I am

God Bless America keep her free from socialism is my hope and prayer

John T

Boy, I didn't think I would get this much flack. What phase of the moon are we in ? LOL. John I am thinking along the same line as you. How can these coils be labeled in a simpler way for those who do not understand? I am always thinking of a way to make an improvement. I suppose there could be six lines of printing on the coil giving an explanation but that will probably be misconstrued by today's mechanics. The old round coil has been a thing of the past on most engines for quite some time now and those who worked on vehicles back in the day are either too old to hold a wrench or are gone. Back in the day the two banger mechanic knew what to use as did the Ford, Chevy and every other brand mechanics. Not so today! When I made this post I was a little frustrated with undoing a wiring job done by someone who did not know what he was doing. A poorly crimped spade connector was put on the factory wire that feeds the coil. The spade connector was plugged into a male spade on a short pigtail that had a cheap thin flimsy forked connector on the coil end that was squished out from under the nut on the primary side of the coil. This tractor should have a 12V coil with resistance. We know that, someone else did not! It looks to me like someone had put a ceramic resistor with male spade connectors somewhere close to the 6V coil but removed it for some reason, hence the short jumper with a male spade that plugged into the barely crimped on non original female spade on the factory wire and a fork on the other end that went to the coil.

Shoddy barely workable flimsy wiring wrapped in tape doesn't bother some people. If it works, fine with them. I do not go by that book and never will.

John I am thinking along the same line as you.

Hey that makes the two of us at least lol

Nice chatting with you

John T

It could be simple, such as:

1.5 Ohm spark coil
Use with a 6 volt system
Or 12 volt with 1.5 Ohm
Ballast resistor in series

A 12 volt rated coil:

3.3 Ohm spark coil
For use on 12 volt
systems no resistor
in the circuit

But simple is relative
some are not related at all Jim

I'm not a fan of using the least accurate
part of a multimeter, the ohmmeter.
Apply 6v to the 6v coil and measure the
current. Typically 1.5 ohm coil will use
4 amps when 6v is applied.
Ohm's law.
If you are planning to use any coil on
12v the size of the ballast resistor
should limit the current to 4 amps.
It's that simple.

(quoted from post at 14:19:28 05/21/21) I'm not a fan of using the least accurate
part of a multimeter, the ohmmeter.
Apply 6v to the 6v coil and measure the
current. Typically 1.5 ohm coil will use
4 amps when 6v is applied.
Ohm's law.
If you are planning to use any coil on
12v the size of the ballast resistor
should limit the current to 4 amps.
It's that simple.

Click to expand...

he problem, GEO, is that the "white blobs" (even those sold under the same part number) are well known to be UNKNOWN resistance......may vary by 3:1. Most don't even specify a resistance value. You need a box full to experiment & reach 4 amperes. I'm fortunate to have a box full.