Hi Everyone,
I have a 53 F-250 and I have been trying to figure out the electrical. It has been re-wired and it is a home done job. The headlights are 12V and the voltage regulator, which looks to be original (it is riveted to the fender) is marked 12V. The battery cables however look to be positive ground. I'd really like to try and start it, but don't want to do any damage. The regulator is junk as is most of the internal wiring. The ground wire from the generator to the regulator is fried, as are a few other wires. I'd like to do a simple wiring circuit to attempt a start, just to know whether the motor will run. The truck sat for years and has zero rot on the cab, so i think it will be worth the effort to get it running.

Thanks Ed

 

Ed,

IF the regulator is really a 12V unit, and IF the fender is really from a 1953 truck, then the regulator is not original. 53's were definitely 6V positive ground.

Here is a 1956 wiring diagram, but I'm not sure how much good it will do you. 1956 was the first year with 12V electrical gear. I've been ill the past couple of days, so you're going to get a long post since I can't get out to work on my truck. Oh, the joy you must feel right now!



If you just want to get the engine running and handle the lights, etc. later, here are the items you need to address

1. System Voltage - Do you want a 12V negative or a 6V positive truck? I'm guessing you want to go with the 12V negative ground since somebody has already started the conversion.
2. Starter - You can run the starter on 12V - even if it is originally a 6V unit. The starter doesn't run continuously, so it will withstand the over-voltage for some time. I think the only way to really tell if it is a 12V starter would be to take it apart, and measure the field and armature resistance. A local electric motor shop should be able to do that for you if you want.
3. Ignition Coil - I'm pretty sure that the coils themselves are the same for both 6V and 12V systems. In the 12V system, the coil has a ballast resistor in series whenever the starting circuit is NOT engaged. You can see this in the electrical schematic. When you are using the starter, the battery voltage can drop quite a bit, so the starter relay (solenoid) circuit runs full battery voltage to the coil. When the engine starts and is running, the starter relay circuit puts the battery voltage through the ballast resistor and then through the coil so the coil only sees around 6 or 8V. That way, you don't burn out the coil, but you still get a decent spark when starting the beast.
4. Distributor - I'm pretty sure that the distributors don't care much whether you are running a 6V or 12V system. Neither do the points or condenser.

Those are the only items the engine needs to run, unless you have an electric fuel pump, or some other add-on. Here's what I would do to check the engine. I'm assuming you are going to clean up all the contacts and wiring so you have solid connections and good wire.

A. Remove any wires connected to the battery, starter relay (solenoid), and ignition coil/ballast resistor. You might want to take a couple dozen pictures so you can remember where they go, should you ever want to put them back.
B. Make sure you have a 12V (6 cell) battery and a 12V starter relay (solenoid). I don't know if all solenoids are marked, but a new 12V unit at your local auto parts store should be less than $15 if you are unsure of the one you have.
C. Mount the starter relay on the inner fender (if it isn't already there).
D. Connect the battery positive terminal to the battery input terminal on the starter solenoid. You can probably get by with a 4 gage cable, but I wouldn't use anything smaller than a 2 gage cable. The battery input and starter output terminals on the solenoid are the big ones. Usually they are marked or shown in the instructions that come with the unit.
E. Thoroughly clean the starter motor mounting flange, mounting bolts, and bell housing mounting ring. This is where the starter gets it's ground from, so take your time and make sure you have clean, bright metal-to-metal contact when you put the starter back in.
F. Connect the starter output terminal of the starter relay (solenoid) to the starter motor input terminal. Again, use nothing lighter than a 2 gage cable.
G. Run the ignition terminal on the starter relay to the coil primary positive input. Run the wire straight to the coil positive input, not to the ballast resistor input. The start (not starter) and ignition terminals are the small ones on the starter relay (solenoid). Usually they are marked "S" for start, and "I" for ignition. You can use wire as small as 18 gage for this.
H. Make sure the coil negative terminal is properly routed to the distributor points and then to ground within the distributor. The distributor wiring should already be in place. If it is in reasonable shape, clean it up a little and use it. If you need to replace the wire to the coil negative input, you can use wire as small as 18 gage.
I. Run a wire from the battery plus terminal (or the solenoid battery input terminal) to a toggle switch, then to the coil ballast resistor input. This will supply the ignition voltage once you have the engine started. Leave the switch off (open circuit) until you are ready to start the engine. You can use wire as small as 18 gage for this.
J. Run a wire from the battery terminal on the solenoid to a momentary switch (normally open), and then to the start terminal on the solenoid. This is what you will use to start the engine. You can buy a start switch with alligator clips at your local auto parts store. If you like sparks, you can just use a length of wire from the battery plus terminal, and touch it on the solenoid start terminal whenever you want the starter to run. Just be sure the loose end doesn't dangle around once you are done with the starter. You'll REALLY get sparks if it hits something grounded. You can use wire as small as 16 gage for this.
K. Run a ground cable from the battery negative to the engine block. Don't use anything smaller than a 2 gage wire for this.
L. Finally, run a ground wire from the battery negative terminal to the starter solenoid, or to the fender where the solenoid is mounted. Normally, you would cound on the truck frame to provide this ground - but we all know how flaky that can be on a truck that hasn't been run in a while. You can use wire as small as 16 gage for this.

When you are ready to start the engine, flip the toggle switch on, and then press the momentary starting switch or touch the length of wire to the starter relay start terminal. Don't forget to flip the toggle switch off when you are done messing with the engine.

Once you have the engine checked out, I'd get myself a wiring harness from one of the usual vendors, like MotorHaven right here on FTE. Check each item (regulator, generator, starter, etc.) as you go and get it all wired properly so you don't have to worry about a puff of smoke and a long walk home.

Comments from somebody who actually knows what they are talking about would be welcomed by Ed, I suspect. I would welcome them too, if for no other reason than to give me something to read.

 

For a down and dirty "will it run" just supply 12 volts to the resistor on the coil (or use a VW bug coil which does not need a resistor) and jumper the starter solonoid with a switch made for that purpose or a screwdriver. All other wiring except battery cables can be disconnected.

 

George and Scot,
Thanks for your replies, I will have to study this a little more and figure out what the guy actually did before I start it. George, great project site, I'm impressed with the content but intimidated with the work........lol.....thanks again....

Ed