24 Volt Military Coil Modification

[delta31]

Truck is 24 volt but using a civilian distributor and civilian oil pump.

Is it possible hook a coil wire to a military 24 volt coil so that it can be sued with a civilian distributor?
Has anyone hear done that? Were running a Bosch 24 volt coil that looked like a regular coil but that one has failed.
A plan b is a 24 to 12 converter but try to avoid that. 24 volt civilian coils appear to be extremely rare and quite expensive.
Appreciate any ideas?

Thanks

[just me]

24 volt coils are tougher in the US. In Europe they are common.
I've got a couple I picked up from a marine supply. Some boats are 24v.

[John Mc]

Pertronix sells 24V ignition systems. They do sell coils, but I don't know if they sell coils intended for use with 24V systems. Worth a call to ask them.

[just me]

They don't. I called a few weeks ago.

[U404S]

I use 24 volt Pertronix epoxy filled Flamethrower coils on my Mercedes Unimog 404 trucks. The part number is 40611. These are used with the Pertronix electronic ignition conversion kits. I have never burned one out. Those M180 motors will turn 4,000 rpm’s all day. The original Bosch 24 volt coils that came with these trucks are durable as well. When I have time, I may adapt one of those coils to the outside of the military distributor for potentially higher reliability over the fullness of time.

[John Mc]

I use 24 volt Pertronix epoxy filled Flamethrower coils on my Mercedes Unimog 404 trucks. The part number is 40611. I have never burned one out.

I don't see any mention of the system voltage the coil is designed for on the 40611 page of the Pertronix web site or in the installation manual (the manual references 6 & 12V systems, but does not mention model 40611)

Are you using a ballast resistor to drop the voltage, or are you using a direct 24V connection to power the coil?

[John Mc]

Truck is 24 volt but using a civilian distributor and civilian oil pump.

Is it possible hook a coil wire to a military 24 volt coil so that it can be sued with a civilian distributor?
Has anyone hear done that? Were running a Bosch 24 volt coil that looked like a regular coil but that one has failed.
A plan b is a 24 to 12 converter but try to avoid that. 24 volt civilian coils appear to be extremely rare and quite expensive.
Appreciate any ideas?

Thanks

Have you looked at the 24V coils sold by Debella Jeep? They are made to mount inside the waterproof military distributor, but I wonder if they couldn;t just be mounted externally, if you have a civilian distributor?

Debella coil:

COIL 24 VOLT NEW 1 B.jpg (48.88 KiB) Viewed 3301 times

[NAM VET]

installed a DeBella coil in my military dizzy last summer, thus far all good. hal

[delta31]

Currently the truck is all 24 volt with the only exception of the ignition coil. This is because the distributor is in good shape and the oil
pump is new. We were running a used Bosch 24 volt coil that we got off Ebay and that lasted about a year.

Right now we are doing a temp work around with a 12 volt coil hooked to the first battery to just moved the truck around.

I had thought that the 24 volts could be reduced to 12 volts using a pair of resistors though I had not found anyone that had done this.

[PoW]

What distributor are you running? Remote running a coil with the waterproof dist is tough to do.

PoW

[John Mc]

What distributor are you running? Remote running a coil with the waterproof dist is tough to do.

First post says civilian distributor.

installed a DeBella coil in my military dizzy last summer, thus far all good. hal

I've got 5000+ miles on my Debella Jeeps coil with a Pertronix MV-161A electronic ignition. I have had absolutely no problems with this set up: easy starting, cold starts (including a few at 15˚F), hot starts, stop and go traffic in 90˚ weather, 300+ mile trip where I was driving 45-50 MPH the whole time (other than when a hil slowed me down), hauling 4000# load through hilly terrain (1000# in the bed, 3000# on the trailer). Very happy with it so far.

I had thought that the 24 volts could be reduced to 12 volts using a pair of resistors though I had not found anyone that had done this.

I don't think you need a pair of resistors. I believe you should be able to accomplish this with a single resistor in the positive feed between the ignition switch and the coil. I'd look for a ballast resistor with the resistance (ohms) as close to the resistance of the primary windings of your coil. The voltage is dropped in proportion to the two resistances. So if they are equal, you are splitting the voltage in half. (NOTE: if you are running an electronic ignition, I would discuss your plans with the manufacturer's tech support.) Ballast resistors are available from most auto parts stores. Unfortunately, some of them can't tell you what the Ohm value is for some of the resistors they sell: all they can tell you is "this one fits a 1965-1979 Ford Mustang".

[ashyers]

An M37 I worked on had a 12v coil and civilian dizzy with a ballast resistor with a 24v system. It worked fine until the resistor's terminal failed due to vibration. You sure didn't want to touch if after it had been running for a while! Unfortunately I don't recall the resistance, but you should be able to calculate that.

I'd consider doing the same if I had the parts. The 24v stuff works OK, but it's $ and makes diagnosis more difficult.

Andy

[T. Highway]

Great information about the Debella Jeeps parts 24 volt coils being available.
Thank you for sharing the information.

Regards,
Bert

[John Mc]

When I bought Brutus, he had two batteries set up for 24 V which ran the starter, but the ignition was a civilian 12 V distributor. They ran this off a 24V to 12V DC to DC converter. It was a large one. It also ran the horn and the lights. I had no problems with it, other than the fact that the horn was rather weak-sounding when the highbeams were on (The converter was not quite big enough to run all of the 12 V accessories at once.)

We switched the truck back to a pure 24 V system when we installed a rebuilt engine.

[ashyers]

delta31,
What did you end up doing for a coil?

I just picked up a civilian vacuum advance dizzy I'd like to try out and am looking for coil options.

Andy