I have decided to switch my 55 f100 from the old 6 volt system to the modern 12 volt system. One question I have is can I just change the old 6 volt ignition coil and distributor on my 223 to a new 12 volt part or is there something I'm missing here?

 

You won't have to change the distributer, but you will have to put in a 12V coil. The wire that runs from the ignition switch to the coil should have a resistor in it called a ballast resistor. Usually the ballast resistor is mounted on or near the coil and it'll drop the voltage to the coil down to something like 9.6 volts.

The other concerns that you will have will be to deal with the 6v instruments and lights. You'll have to either change the instruments out to a modern system, or...figure out a way to reduce the voltage to 6V for those systems. There are resistor systems available, but I think those are pretty old school....there are high efficency DC to DC converters available from hobby suppliers that could be packaged into an effective voltage reducer. RC airplane guys use these devices called a battery eliminator circuit (BEC) to drop their LiPo Battery voltage down to 6 volts for the recievers in their airplanes. Since these are efficient devices that generate little to no excess heat, and are programmable to put out 6 volts, they should be a good application for using the 6V instruments in an old truck. Some are good for up to 20 to 30 amps.
Castle Creations | CC BEC and CC BEC Pro

After that...lights...you'll have to put 12V light bulbs in everywhere.

You'll have to pay attention to the fact that the original system was positive ground & any 12V alternator system that you put in will be a negative ground system.

The 6V starter will work well with 12 volts going to it....it'll just turn twice as fast.

Dan

 

6v solenoid has 1 less post than a 12v solenoid (and the 2 terminal starter buttons completes a circuit in 12v, where in 6v the 1 terminal starter button just grounds out a circuit). You can actually get away with leaving the solenoid, but for some reason they tend to burn out shortly after a conversion (same is true of coil - but you MUST add a ballast resistor if you keep the old coil). In my opinion not worth it, replace the coil. Switches and wires are fine and sending units are all fine - all the wiring is actually twice the capacity of what you need.
Condensor is another thing to probably replace - it's rumored in other threads you don't have to, but some found that if you don't, it won't start. (I replaced it on mine cause it wouldn't start, but then later it started with new spark plugs).

As dan mentioned, the coil now has power coming in to the - terminal and the + goes to the dizzy, you need to reverse that as well as changing the - battery feed to ground instead of to solenoid.

If you have a heater, the blower motor is 6v I bought the 4a ceramic voltage reducer from LMC and it seems to work fine.

Does your year have a electric wiper (6v if it does)... then you need a voltage reducer on that as well (or if it doesn't work, then replace it with a 12v).

[edit] and cigar lighter - if you leave the old one, it is rumored to fly all the way across the cab when you use it - dang hot very fast.

The safe way to do the conversion is to convert everything you can think of and DOUBLE check all your work, then use a 2-3a trickle charger to test each circuit 1 by 1. You won't have enough juice to run headlights for more than a second, and you can't run high beams at all... but the low amperage ensures no blown fuses and no smoking smoldering wire. If something doesn't work as expected then you stop and figure it out before you put that massive 300a battery in and let all the magic smoke out. As simple as these old girls are there is actually a lot of circuits in them - don't forget any.

The trickle charger I got was a dual 6v / 12v 2a with overload protection (instead of frying it just goes into fault mode and needs to be unplugged to reset).. It worked great for testing the blower motor, etc before buying voltage reducers.

 

You'll need a ballast resistor with a new 12V coil...but...that's what the second post is for on the 12V solenoid. The second post provides a 12V circuit to the coil for a hotter spark during starting. After you release the starter button (or key), the solenoid stops providing power, and the coil gets its power from the ignition switch...hopefully through a ballast resistor.

Dan

 

The above three posts pretty much outline why I'm leaving mine 6 volt for now. I got tired just reading all that. I can't imagine doing all that work unless I was already in the middle of a complete rebuild/restoration.

 

I'll post a video of how it starts EVERY time now - I love it, it starts like my 2006 (which has a momentary stop on the key - the computer takes over and runs the starter for as long as it needs, you don't hold the key to crank) every time 1/4 second bam she launches to life. No weak headlights, no hard starts... it's a new vehicle to me.

 

Of course the 12 volt has its advantages. Heck, my 50 that I'm rebuilding had and will have a 12 volt system. Each person has to decide whether they want to do the conversion or not. Take me and my 49 for instance. It's still 6 volt. The most action it usually gets is an 11 mile trip down this river to work or the occasional trip to town for ice cream or to my parents' house. I live in the country. If I lived in a fast-paced urban place like a lot of you guys, it would be a different story. If my truck fails to start at the local Dairy Queen, then there's a really good chance that somebody I know will be standing nearby to help me bump start it. That doesn't always happen in the big towns with the big fast-paced freeways. It's all a matter of how demanding your driving environment is, and whether it's in your best interest safety-wise (if nothing else) to make the conversion.

 

I do have to agree, it is a LOT of work, I chose to do mine because of the condition it was in (electrical was Trashed capital T). If I had good wiring when I got, I would have probably saved all the work, cause it was sure a lot of work. But with the way it starts, runs, shines, etc I do have to say it was worth it for the "new" effect, it feels like a brand new girlfriend, not a tired old wife.

 

Up to you on your choice but unless your adding a stereo or want brighter lights 6 volt does it fine. I live in a city and no issues with my 6 volt truck.

 

X2 and I know exactly where you're coming from, no kidding. :)

Why all the fuss is that the OP wants to use this old clunker as a work
truck and it can't be breaking down and lights not working 100% right
and stuff like that, it needs to be reliable in every way. It can be done
and won't be that tough to do, it will just take time and money. BTDT

Otherwise I'd be on the 6-volters' side of the fence! :)

The 6v system has bigger wire running through it than the new 12v
systems have, it's gonna be cool when the voltage gets doubled. :)

Alvin in AZ
ps- Can we talk about politics or worse... "K&N filters" now? ;)

 

Converting to a 12 volt on the 223 is a piece of cake. Switch over to the Chrysler Ignition Coil and Ballast Resistor and change the +/- wires around and that's it. is it original/stock? No, but it is more reliable and not that difficult to do. The 6v starter working in 12 volts fixes the slow starts especially in the colder months. I am thrilled I spent $35 on the new parts and an afternoon wiring it up. It's the other parts of the conversion that are the pain (ignition, dash, lights, etc.)