I have purchased an American Autowire complete wiring harness for my 67 F100. The wiring harness comes with alternator wiring for a 1-wire alternator. I know the one wire alternator is an upgrade; but I was wondering if someone has modified the complete harness to accept an original 3-wire alternator hook-up. Thanks for any ideas.
Jim

 

It's easily doable. Well, pretty much anyway. They just want to save wiring hassle and cost by insisting it's better to run a 1-wire, but it's not that bad to run a 3-wire whether externally regulated like original, or even internally regulated.
You will lose the ammeter function of course, but you've lost that already with the new harness. Converting to a volt-meter, or just adding a separate one somewhere, will get you past the bit about not knowing what's going on with the charging system.

Your ignition switch should still have a wire position where the terminal is hot in ON position only. This is what you need. You do not want the alternator energized while the key is in the ACC position or you won't be able to listen to your radio very long.
Find that terminal and which wire(s) connect to it in the new harness.

The regulator 4-position connector has terminals marked "F, S, A, I" somewhere (or IASF depending on how you're looking at it). Usually on the regulator itself, but this positioning is critical. There are two ways to orient the wires per Ford, but let's keep with the original orientation assuming you have an ammeter in the cluster. Did your truck have an ammeter, or just a battery charge indicator lamp?

Your '67 had a different setup than later models, but we'll work with the versions that were more common later. Much simpler and easier to follow the wiring diagrams on.
Keeping your regulator in the same place might make it harder. Is yours up on the core support next to the radiator? If so, it might be easier to move it rearward along the fender apron to an area closer to the firewall. Up to you though, as you're going to be making wire runs yourself so can do whatever you like. Might be kind of retro cool to keep it in the early location, but take a look around and even look at some '72 and later models (or maybe '73 and later would be better) to see how you like the later orientation.

Here are the connections you'll be making:

From the "F" terminal of the regulator you run a wire (about 14ga is fine) to the FLD terminal of the alternator. This is the "field" wire and is what tells the alternator just how much juice to put into the system.
From the "S" terminal find that wire from the ignition switch that is hot in ON only and connect it there. Originally the S stands for "stator" but I like to think of it as "switched" so it helps me remember how things work.
From the "A" terminal run a wire directly to a battery positive source. This can be directly to the battery, or for a cleaner connection go to the battery side of the starter relay/solenoid. Original wiring has it spliced to one of the large Black main power wires. You can connect it wherever convenient so that it gets a good clean signal from the battery. This is the sensing wire that tells the regulator how much to tell the field wire how much to put back into the system to keep the battery charged.
The "I" terminal is unused in this setup. It is used when you don't have an ammeter, but you can still use the ammeter orientation and it will charge.

The connections on the back of the alternator are only three, or four depending on how you do one thing.
The large BAT terminal with the red insulator will have a wire going from there to the battery side of the starter relay.
The medium FLD terminal gets the wire straight from the F terminal of the regulator.
The medium STA terminal is either unused (most cases) or can be used to power an electric carburetor choke. Most 1G models this will remain unused.
The small GRD terminal on the back of the alternator needs a wire (can be small gauge) run to one of the mounting bolts of the regulator. This gives the alternator and regulator the same ground potential and is likely one of the reasons we have internally regulated alternators in the first place.
It's also there to keep the regulator healthy in case the bolts ever work loose. You can fry a regulator if it's connected to power and gets "un-grounded" at any point.

That's it. Lots of writing but very few wires to run. But they are all important.

Make sure that your mounting points are clean, rust and paint free, and tight. If you have painted the engine, alternator and brackets, and the holes are rusty or painted within, add a secondary ground wire between the alternator case and the engine.
Grounding is definitely done through clean and paint-free mounting points from the alternator to the engine. But adding a secondary ground wire is not a bad practice for the higher output alternators. Once you get to 70a and above it's not a bad thing to add grounds.
But the small ground between the alternator and regulator mounting bolt remains important no matter what, and Ford always ran one.

If any of that doesn't make sense, or if something else comes up, or if you have a charge light instead of a gauge, we can move some wires around if you are more comfortable that way.
But it's definitely going to look different from your old '67 wiring if I remember my diagrams, You won't need some of the old components. Just an alternator and a regulator.
Might need to go with a newer version of the regulator, but this might all work with the old one work if you are keeping it.

Paul

 

Thanks, Paul

Great directions, I have printed it out. Will be a while before truck is ready. 390 is done. C6 is rebuilt. May parts cleaned and painted. Truck went to body shop 2 weeks ago and could be a couple months or more to get it back.

Thanks, again,
Jim

 

Sounds great. Got any old pics of how the engine compartment was laid out previously?
Is it bare of any wiring now for paint?

And speaking of paint... Just the exact scenario for you to be certain to add grounds, and to make sure the ones you have are very well mated to the sheet metal and other bits under the hood. Keeping this all in your mind while the build goes on will keep things happily working away (electrically anyway) for the future.

The new paint might mean too that you would prefer to keep the components in their old positions in order to utilize the old holes. This should work just fine as long as you can make all the wiring match up.
In the meantime you can use all the time waiting to source/scrounge up some wires of the correct colors even. The Green w/red stripe, the Yellow (or Yellow w/white from later trucks) and the Orange wires were extremely common on Ford trucks. You might even be able to salvage some of your old wires? Or are they all gone at this point?

Paul

 

Paul,

I totally stripped the entire wiring from the truck. But I still have it....I did not cut anything, but carefully removed all the harnesses. The old voltage regulator was between the battery (up front) and the firewall; close to the starter solenoid. So probably in a good position. I have upgraded to an electronic regulator. Interestingly, nothing on the paperwork even mentions "grounding"; probably assuming the bolt down is good enough. No worries, I am a believer in grounding (former auto business owner). Grounding in several locations for continuity throughout.

I will have to decide on changing the ammeter to a voltmeter. I think you can get an update to fit in the original spot on the dash cluster.

Jim

 

I sent the ammeter out of my 72 f250 to Rocketman(RCCI). He coverted it to voltmeter and shipped it back out very quickly.
https://rccinnovations.com
Here is the link I didnt add before.

 

Thanks!

I will give them a try, 1Browski

Jim Sygitowicz

 

1browski,

I will give them a try. Thanks

Jim Sygitowicz

 

I went through this exact situation recently. Used the AAW kit but insisted on a 3g alt. They don't fit great on my 390fe, not enough clearance between the head and the rear of the alt. I finally found that the auto one part barely fits.

If I were to do it over again I would try and find a 1-wire that fits.

I also converted my ammeter to volt meter by way of rocket man.

 

This is the way Ford wired up the external regulators.
You will notice with only the charge indicator light there is a 15-ohm resistor wire paired with the light. It is there so the alt. still gets exciter voltage if the bulb burns out.

 

Thanks for the diagrams.

 

Is there a wiring change when converting your ammeter to a voltmeter.. I have sent in the original 67 F100 ammeter to Rocket Man for conversion. I was wondering if the two wires on the ammeter in the cluster can remain as they were when the voltmeter is installed.

 

Was hoping someone else would answer since I don't know with 100% certainty. But I don't think you need to re-wire anything important.
The new volt gauge simply needs a 12v keyed source and a ground. No fancy connections to the regulator wiring.
But I don't know how each truck is wired exactly with those wires. You could possibly cut them under the hood and connect them to different sources, or eliminate them on the back of the cluster and use new wires supplied by you.
Presumably the converted gauge will come with basic instructions? Again, I don't know as I have not dealt with it.

Your instrument cluster is pre-circuit board type? Correct?

Paul

 

Yes, it is the pre-circuit board. I think I can find an under the dash connection that is only hot with ignition in "run" position. Eliminates any draw from the battery when the car is turned off. Ground, of course is no problem. Now I am in the "long wait" for the body shop work.

Thanks for the info.

 

Ive watched this video before about the ammeter/voltmeter conversion.