ignition coil blew up today...

[surfdog]

Working the m108 light crane today. Replaced the condensor, emeried down the points to get the spark back. Ran great, then when I went to restart it again... Bang and a big cloud of smoke. Thought I caught the engine on fire so grabbed the extinguisher.

This is what I found...

 

[steelandcanvas]

Looks like she just couldn't take that tune-up. hope you're Ok and the damages were limited. Don't forget to get that fire extingusher refilled.

 

[DieselBob]

Just wrap the wire back around the core stuff it back in the tube, add oil and super glue the tower back on and go..... That's only about the third time I can remember seeing that happen.

 

[surfdog]

I wonder if the last owner put in a 12v coil instead of 24v. I searched the coil number ( D-511) and it looks like it comes back as a coil for a 60's Chevy.

Anyone know if putting 24v into a 12v coil would cause something like this?

 

[jatonka]

It could

 

[doghead]

Yes, it can. I recall this being an issue back when people "converted" 6 volt VW bugs to 12v and did not change the coil. It would work just fine,unless you left the key on and the points were closed. Then, after a few minutes, BANG, the coil explodes.

I did it at least once myself.

You could add a resistor in front of a 12V coil, if you can't find a 24V coil.

 

[Stretch44875]

Yep, I blew a coil once the same way. Had the ballast resistor jumped out and forgot about it, it blew about 1/2 hour later. I don't think the gasser deuces have a resistor on them, but 24v to a 12v coil will do the trick.

 

[robert c neth]

the 12 volt coil can be bought to be used without a resister dont know about the 24 volt ones.

 

[JasonS]

I wonder if the last owner put in a 12v coil instead of 24v. I searched the coil number ( D-511) and it looks like it comes back as a coil for a 60's Chevy.

Anyone know if putting 24v into a 12v coil would cause something like this?

With few exception, there is no such thing as a 6, 12, or 24V coil. When GM went from 6 to 12V, they just addded a ballast resistor to keep the current within limits. I have measured numerous reo and gmc coils and each measured identical to every old old 6 or 12V coil that I could find. The "24V" coil in the gmc and reo gassers is a normal coil with a ballast resistor.

 

[JasonS]

Working the m108 light crane today. Replaced the condensor, emeried down the points to get the spark back. Ran great, then when I went to restart it again... Bang and a big cloud of smoke. Thought I caught the engine on fire so grabbed the extinguisher.

This is what I found...

Get a new 12V coil and two ballast resistors.

 

[m109a3uk]

I had it happen to a 1943 ford of mine I parked the Jeep had parked it and left the ignition switched on. I went to pick up another vehicle and whilst away the coil blew. The guys keeping an eye on the vehicles thought that it was a joke I had set up a loud bang and loads of smoke!

 

[Bob USNR]

Big bang theory?

Working the m108 light crane today. Replaced the condensor, emeried down the points to get the spark back. Ran great, then when I went to restart it again... Bang and a big cloud of smoke. Thought I caught the engine on fire so grabbed the extinguisher.

This is what I found...

6vdc and 12vdc units do come specifically for systems "With/resistor" and "Without/resistor".
This difference started appearing on American engines in the late 1940's. The reason for the resistor type coil was to make the engine much easier to start in cold weather.
This was also the time there was an "ignition polarity reversing switch", in the starter linkage, on some engines, too. It evened out the wear on the points so you didn't have to adjust and clean them so often.

Just make sure the voltage, tested across the coil is about 9 to 10 volts for the 12vdc resistor type. The operating voltage for the 6vdc coil is about 5 volts.
The resistors should still be available since there are so many of those engines still on the road.

If you have trouble finding 24vdc coils get a trailer brake voltage adjuster to use to reduce the voltage at your 12vdc coil. As long as the voltage across the coil is correct you will be fine.

e

 

[JasonS]

Comments:

6vdc and 12vdc units do come specifically for systems "With/resistor" and "Without/resistor".
This difference started appearing on American engines in the late 1940's. The reason for the resistor type coil was to make the engine much easier to start in cold weather.
This was also the time there was an "ignition polarity reversing switch", in the starter linkage, on some engines, too. It evened out the wear on the points so you didn't have to adjust and clean them so often.

Just make sure the voltage, tested across the coil is about 9 to 10 volts for the 12vdc resistor type. The operating voltage for the 6vdc coil is about 5 volts.
The resistors should still be available since there are so many of those engines still on the road. This is going to confuse people; not all coils are designed this way.

If you have trouble finding 24vdc coils get a trailer brake voltage adjuster to use to reduce the voltage at your 12vdc coil. As long as the voltage across the coil is correct you will be fine. Neither Reo nor GMC used a 24 volt coiil. As long as you use two 1.5 ohm ballast resistors you will be fine. The real design variable is the current through the points.
e

Given that you have the civilian distributor, you can easily convert to Pertronix electronic ignition.