24 Volt Military Coil Modification

[John Mc]

ashyers -

If you are a 24V system, is there some reason you don't want to go with a Debella Coil? If you are running a 12V system, there are lots of options if you are not trying to find one that fits inside one of the waterproof military distributors.

[ashyers]

John Mc,
My truck is 24v with a stock igniter system.

I'm looking at swapping in a civilian dizzy with vacuum advance and cheaper wires and plugs. I've been playing around with finding the limits of the compression ratio on these engines and a civilian dizzy is easier to play with when it comes to changing the timing curve and it would be nice to have vacuum advance available.

The trick seems to be finding a 24v coil. I may have to use a 12v unit with a ballast resistor.

Andy

[Rdinatal]

Pardon me if I'm off base here as I've only had my M37 for a couple of months.

If you have a 12v coil why not run the ignition switch from one battery (1st one away from ground) to the coil? That way you don't need the resistor.

[PoW]

Unbalanced charging happens and ruins them.

Because eventually you'll wind up with one 22 volt battery, and another 2 volt one.

PoW

[John Mc]

Andy -

The Debella Jeep coil linked earlier in this thread is a 24V coil. It's designed to fit inside the original 24V military distributor, but I'm not sure why it couldn't be mounted outside. I have Peter Debella's email. I'll ask him if there is some concern with that.

[ashyers]

The issue with the stock style coil is that there is no way to retain the coil wire.

[just me]

Widen your search to europe and you will find plenty of 24v coils. For example:
https://www.desmetjeep.com/product/deta ... d=0&page=1

[John Mc]

Response from Peter Debella to my inquiry about 24V coils:

I do have traditional 24 Volt coils that can be mounted externally, but none are in the building at the moment. Stored in a different location. I am away till the week of Aug. 21st. Could dig some out then. They are $65.00.

Regards,
Peter DeBella

If you need it, his email is: sales@debellajeepparts.com

I'm sure there are other options available somewhere as well: there are marine engines and some larger gas trucks with 24V ignition systems.

[1952m37lw]

I bought a nos 24v external coil from debella jeep, you have to call him and ask for it. I also bought a new external coil for a Hotchkiss M201 from Jeep Est out of France. The one from France was about $80 with shipping and it runs good.

[ashyers]

Thanks Crew!
Looks like there are some options for me to look into.

I think I've found the necessary parts to get the vacuum advance dizzy I have up and running so I just need to pick up a civilian oil pump and the experiment can begin. One concern I have is the interaction of the governor and the advance mechanism. I'm not sure if it will be an issue, but if some kind of weird feedback loop is created when the engine is at the governed RPM strange things may happen. We'll see...

Andy

[John Mc]

Are you using points and condenser, or electronic ignition?

[ashyers]

John,
I was running a Pertronix module for ~5 years. I had issues a few weeks back and called their tech line to see how to test the unit. It was fried. In my discussion with the tech he asked if I was running solid core wires. I said yes, the stock wires are solid core. He said that was likely what fried the unit. I guess the chips in the current modules are not tolerant of solid core wires.

So back to points!

[PoW]

Somewhere I've seen shielded resistor plugs.

Aircraft, I believe.

PoW

[John Mc]

John,
I was running a Pertronix module for ~5 years. I had issues a few weeks back and called their tech line to see how to test the unit. It was fried. In my discussion with the tech he asked if I was running solid core wires. I said yes, the stock wires are solid core. He said that was likely what fried the unit. I guess the chips in the current modules are not tolerant of solid core wires.

So back to points!

Wow. First I've heard of that. Most of the burnouts I've heard about are attributed to someone leaving the ignition on for an extended period with the engine not running.