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  1. #1
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    1955 Ford 640

    Default Ford 640 12 Volt Conversion Clean Up

    I bought this tractor well after the 12 Volt conversion was done to it. I was told the charging system worked but the Volt Meter wouldn't so I wasn't too concerned. I knew the 12V sealed beam lights didn't work but I figured that would be a fairly easy fix. Now that I have the hood off to fix a radiator issue I decided to tackle the small problem with the charging system. I spent last weekend gingerly unwrapping (breaking apart brittle plastic tape was more like it) gangs of wires in order not to break or disconnect anything as all I wanted to do was a simple repair. I didn't want to rewire the whole things. I had printed out the stock 6V wiring diagram and the standard 12V conversion diagram to see which mine represented the closest. As it turns out - neither.

    I decided I needed to do my own wiring diagram. On it I numbered the wires and then I put tape on the wires themselves so I can make sure to account for everything. I've attached the wiring diagram.

    My two goals are:
    1.) Get the charging system working.
    2.) Get the lights working.

    A few notes and observations:

    1.) The alternator is a Delco Remy with the following markings in various places
    10-b
    78amp
    200y
    N112
    12V
    Neg

    I had it off last year and had it tested at an Autozone. The best we can tell it came from a 1985 3/4 ton Chevy diesel truck. It might be a 12SI. There is a single wire attached to it on the Batt terminal and it goes to the Voltage Regulator. Nothing is connected to the two blade connectors.

    2.) The Voltage Regulator is a 6V regulator (see picture).

    3.) The 12V Coil is an External Resistor type (see picture) and there is an external resistor.

    4.) Although the alternator goes to the 6V voltage regulator, the voltage regulator itself isn't hooked up to anything. It is grounded to the same mounting plate as the terminal block. And there is another wire that comes form that same ground screw that went to the front of the tractor near the alternator but wasn't hooked up.

    5.) Wire #3 from the Terminal Block also went to the front of the tractor in the same taped up gang of wires and also wasn't hooked to anything. But it's hot - ask me how I know!

    6.) There's lots of cut off and taped up wires that go nowhere. I suspect those are from the original 6V wiring set up. I'm going to get rid of those if I can.

    So, with the rat's nest I have under there and the age of the wires, I suspect the best thing to do is to rewire it. Any advice, drawings, suggestions or prayers would be most appreciated. When referring to a wire please include the wire number from the diagram is you can just to cut down on confusion.

    Thanks everyone!
    Attached Thumbnails Attached Thumbnails -2013-01-06-11-18-a   -2013-01-01-12-08-a  
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    Steve

    1955 Ford 640 - Old Dirt needs an Old Tractor

  2. #2
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    1955 Ford 640

    Default Re: Ford 640 12 Volt Conversion Clean Up

    One change. The Volt Meter I'm showing on my wiring diagram is actually the Ammeter on the instrument panel of course. It was a long day.....
    Steve

    1955 Ford 640 - Old Dirt needs an Old Tractor

  3. #3
    Epic Contributor Soundguy's Avatar
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    Default Re: Ford 640 12 Volt Conversion Clean Up

    hack the wires off.

    get a real 12v coil.. napa ic14sb 16$

    wire from alt charge to one side of an ammeter other side of ammeter to battery site of start solenoid. wire from alt side of ammeter to key, to coil. wire from alt side of ammeter to lamp switch to lamps.

    wire crom coil side of key thru a 194 marker bulb to #1 terminal on al.

    wire from charge stud on alt to #2 terminal on alt.

    key on. lamp lights.

    get her over 500 rpm.. lamp should go out and ammeter show charge. if backwards.. swap wires side to side.

    all laods on alt side of meter.. battery on other side by itself.

    that's it

  4. #4
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    1955 Ford 640

    Default Re: Ford 640 12 Volt Conversion Clean Up

    Quote Originally Posted by Soundguy View Post
    hack the wires off.

    get a real 12v coil.. napa ic14sb 16$

    wire from alt charge to one side of an ammeter other side of ammeter to battery site of start solenoid. wire from alt side of ammeter to key, to coil. wire from alt side of ammeter to lamp switch to lamps.

    wire crom coil side of key thru a 194 marker bulb to #1 terminal on al.

    wire from charge stud on alt to #2 terminal on alt.

    key on. lamp lights.

    get her over 500 rpm.. lamp should go out and ammeter show charge. if backwards.. swap wires side to side.

    all laods on alt side of meter.. battery on other side by itself.

    that's it
    Thanks, SG. That's kind of what I figured I'd have to do. The wires that are there are at least as old as that brittle plastic wrapping I pulled so it should be replaced anyway. Thanks for the advise.
    Steve

    1955 Ford 640 - Old Dirt needs an Old Tractor

  5. #5
    Epic Contributor Soundguy's Avatar
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    Default Re: Ford 640 12 Volt Conversion Clean Up

    post back if you hit a snag. wireing on these old tractros is 1-2-3/A-B-C

  6. #6
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    Default Re: Ford 640 12 Volt Conversion Clean Up

    Quote Originally Posted by Soundguy View Post
    post back if you hit a snag. wireing on these old tractros is 1-2-3/A-B-C
    SG, question for you. I rewired the tractor. It is so much cleaner in there and so much simpler. I haven't tried starting it yet as the radiator is off and the engine is drained. But it does turn over when I hit the button. The only wire I haven't done yet is the one from the alternator with the light in it. You said to use a #194 socket and bulb. On the dash of the 640 is a hole just above the steering column that is 1 1/8". I think I can put a licenses plate light in like this: Blazer/Round license light (B160) | License Plate Lighting | AutoZone.com . It is 1 1/4" and uses a #67 bulb instead which has a slightly higher wattage and amp draw [3.78 w VS 9.66 w and .27amps VS .69amps]. Is that going to make a difference? I could make this light fit real nice in that hole with a dremel. It is water tight and won't get hassled too much by hands and gloves. Thanks for all the input. It's been great!
    Steve

    1955 Ford 640 - Old Dirt needs an Old Tractor

  7. #7
    Epic Contributor Soundguy's Avatar
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    Default Re: Ford 640 12 Volt Conversion Clean Up

    try it before you mount it.

    If it is higher wattage, it will deffinately turnthe alternator on and make it work. after you get the machine running and alt charging, then turnt he key off. if the machine shuts down, then you are good. If the lamp is TOO high of wattage, it can actually allow enough current in the circuit to keep the ignition alive.

    I'm betting you are fine with a license plate lamp though.

  8. #8
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    1955 Ford 640

    Default Re: Ford 640 12 Volt Conversion Clean Up

    SG, Finally got over there and got it all done last weekend. Had to go with the 194 bulb as the license plate unit was a single wire grounded piece that wouldn't work. Still looking for a way to mount that in a protected location. But, all the lights work and everything has been soldered, shrink wrapped and organized and protected in corrugated plastic sheathing. After fluid changes and other winter maintenance items, she fired right off, the ammeter came up to about 7-8 (I know I need a new battery) and the lights worked. Thanks for all the help.
    Steve

    1955 Ford 640 - Old Dirt needs an Old Tractor

  9. #9
    Epic Contributor Soundguy's Avatar
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    Default Re: Ford 640 12 Volt Conversion Clean Up

    glad to hear!

    post back if ya need any help.

  10. #10
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    Default Re: Ford 640 12 Volt Conversion Clean Up

    SG, haven't been able to get over there much but finally did. I did the wiring per the 3 Wire conversion like you described and shown here: https://www.dropbox.com/s/7rwbu1c75x...203%20Wire.pdf I did use the 194 bulb instead of the diode. It does light up at low RPM and go off at about 500. I had to replace the old battery as the old one wouldn't hold a charge any more. That's done. Lights and everything work. However, I don't think it's charging. The Amp meter doesn't move. Could it just be a bad meter? What steps should I take to figure out if it's charging and how to fix it if it isn't? Thanks for all the help.
    Steve

    1955 Ford 640 - Old Dirt needs an Old Tractor

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