6 volt coil on 12 volts.

[Rudolph]

This is what will happen if you run a 6 volt coil on 12 volts or do not have a ballast resistor in the ignition circuit, my frind was running his Ford Falcon and was sprayed with boiling oil.



https://youtu.be/3jZ1Eceay-c

[RalphG]

Looks dangerous. I had no idea they would do that.

[RalphM]

Wow!
Now I’m going to save all the coils I find for next years Fourth of July celebration!

[Brian]

I dunno....For years I ran my 35 on 6 volts using a generic black bodied coil with a tan colored top. These coils, I don't know the brand, are made in USA. When I subsequently converted the 35 to 12 jolts, I used the same coil. No ballast, nothing. Still running strong after 30-odd years.
I imported from the US, a 1951 Ford 8N tractor. It was 6 volt and used same style coil. I have subsequently converted that machine to 12 volt, again with no ballast etc, and experienced the same trouble free reliability for the past 10 or so years.
Those particular coils are fine on 6 or 12 volts. I've had all the experts on here tell me it can't be, but I assert that what I say is indeed my finding.
Does anyone know that particular brand of ignition coil?

[petehoovie]

Originally Posted by Rudolph

This is what will happen if you run a 6 volt coil on 12 volts or do not have a ballast resistor in the ignition circuit, https://youtu.be/3jZ1Eceay-c

And, without points making and breaking in the ignition circuit as seen in the video above....

[Rudolph]

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Originally Posted by petehoovie

And, without points making and breaking in the ignition circuit as seen in the video above....

like when the ignition is on and the engine isn't running

[Rudolph]

Originally Posted by Brian

I dunno....For years I ran my 35 on 6 volts using a generic black bodied coil with a tan colored top. These coils, I don't know the brand, are made in USA. When I subsequently converted the 35 to 12 jolts, I used the same coil. No ballast, nothing. Still running strong after 30-odd years.
I imported from the US, a 1951 Ford 8N tractor. It was 6 volt and used same style coil. I have subsequently converted that machine to 12 volt, again with no ballast etc, and experienced the same trouble free reliability for the past 10 or so years.
Those particular coils are fine on 6 or 12 volts. I've had all the experts on here tell me it can't be, but I assert that what I say is indeed my finding.
Does anyone know that particular brand of ignition coil?

I have a black coil with a tan top if you want it you cam have it, I have used it on a 12 volt system with no trobble but those alloy bodied coils explode when used with out a ballast resistor,

[Brian]

Rudi, That is THE coil you want for your flathead powered T. [the black one]

[Rudolph]

Originally Posted by Brian

Rudi, That is THE coil you want for your flathead powered T. [the black one]

I got a better one, as I have the electronic ignition its not compatible,

[dumb person]

Didn't someones coil blow up with the engine running? Is that rare?

[rotorwrench]

Originally Posted by Brian

I dunno....For years I ran my 35 on 6 volts using a generic black bodied coil with a tan colored top. These coils, I don't know the brand, are made in USA. When I subsequently converted the 35 to 12 jolts, I used the same coil. No ballast, nothing. Still running strong after 30-odd years.
I imported from the US, a 1951 Ford 8N tractor. It was 6 volt and used same style coil. I have subsequently converted that machine to 12 volt, again with no ballast etc, and experienced the same trouble free reliability for the past 10 or so years.
Those particular coils are fine on 6 or 12 volts. I've had all the experts on here tell me it can't be, but I assert that what I say is indeed my finding.
Does anyone know that particular brand of ignition coil?

The 1935 Ford could still have its original ballast resistor unless someone removed it.

No telling what one of the late 8N tractors with the distributor on the side could have ended up with for a coil over time. The one wire alternator 12-volt conversions for the N and 100 series Ford tractors come with a ballast resistor. Some one may have put a 12-volt compatible coil on there in the past. If it is a 6-volt compatible coil and has no ballast resistor on 12-volts, the coil or breaker components may have lower life spans due to that but it may work OK for an unknown period of time. It just depends on how much you work it.

The ballast resistor is more to control the current flowing to the coil than it is to lower the voltage. Too much unbroken current flow will make the primary side coil winding into an electromagnet and it will just keep getting hotter till something gives. It might burn through a winding on the coil or it might overheat the dielectric compound inside the can like the you-tube movie. Either way it will eventually fail if there is nothing to control the current. When a coil is in operation, the breaker points keep opening and closing the circuit so heat doesn't build up like one that is switched on all the time. Modern 12-volt compatible coils have a primary coil resistance of around 3 Ohms. This is near twice as much resistance as the old 6-volt compatible coils have and this makes a ballast resistor redundant. Many modern coils use a solid epoxy resin compound as an internal dielectric and that stuff seems to be able to take the heat pretty well. I don't know if any manufacture still uses oil in there but you never know.

[JSeery]

Back in my early racing days, went through several coils before I figured out proper resistance. Still carry a reminder on my right hand! Good learning experiance.

[Brian]

All I know is that the coil[s] I'm talking about run equally well on anything from 4 1/2 volts [original 6 volt through firewall mounted resistor], all the way up to full 12 volt [non ballasted].
And it's my understanding that the reason to drop primary voltage is to prolong life of points.

[Rudolph]

Originally Posted by dumb person

Didn't someones coil blow up with the engine running? Is that rare?

My friends XD Falcon 6 cylinder motor was running on the floor with a hose in the cooling system and the coil burst then him and his mate were fighting over the hose as they got covered in hot oil.

[FlatheadTed]

I run the USA beige top

[deuce_roadster]

I would think if you hook any coil up without points opening and closing, and using battery cables instead of primary wire, it would do that. How many amps are being fed?

[JSeery]

It wouldn't be 12 volts, it would most likely be over 14 volts.

[Kahuna]

Like JSeery, I have a small battle scar from a 12 coil.
In 1990, I bought my 39 Ford Std coupe, After working on it
for a year, I wanted to convert it to 12 volts & wanted to keep
the original ignition (Helmet type) & have it appear stock.
I converted the points to electronic using Perlux parts (now Pertronix)
and then needed a coil. At the time no one had 12 volt coils for a Helmet
distributor, but I had seen an ad in Hemmings listed by the late great
George Pounden (some older folks here may remember George from the 50's,
as he did a lot of distributor work & made his own Magnetos. A very famous name in
flathead racing).
He wasn't too far from my office, so I called & asked if he might rewind a coil for me?
He mentioned that he hadn't done one, but was willing to try.
I visited George with 2 Ford coils & he rewound them for a total cost of $120.00.
I get home & install the first one. The engine fires immediately & runs great..for about 3 minutes, then dies. I think, hey, no problem, that old guy probably screwed up. So, I remove the coil and burn the crap out of my hand. I then install the second coil. Again, the engines fires immediately, but also dies after a couple of minutes.
I call George. His first question is did I hook up the ballast resistor? The what?
What's a ballast resistor?
In any event, I finally figure out that I need a resistor. After that adventure, the coils are again repaired (more money & time) and that coil ran like a clock for almost 26 years ( car was sold 2 years ago)
I used the second coil on my 32 & have had no problems in nine years.
Just goes to show that when things are correct, electrical devices will almost run
forever.
On both, I used a ceramic resistor
Sorry for the long story
Jim