Hi I have an 86 302 in my 58 f100. The wiring harness is out of a 69 F100. Here's my deal. The harness is slowly falling apart and what not so I recently purchased an eight circuit harness. It's supposed to be a universal setup but apparently not for a ford. I would like to be able to splice in the charging harness from my current setup or make some sort of a generic harness which I really would prefer to do. I found a diagram in the 48-60 forum but in that diagram the 'S' post from the alternator had nothing running to it where as, my alternator does. Also, the diagram shows nothing coming from the 'I' post on the voltage regulator where once again, mine does. When all is said and done, I will be using a stewart warner amp gauge and would like to eliminate most or all of the '69 harness in the truck. I want to keep it as simple as possible but still fully functionable. Thanks in advance, John

 

If you are going to run the amp gauge like you said, go ahead and use the simple diagram you have which does not use the "I" or the "S" terminals. Just leave them disconnected. Here is that diagram.



The way it was originally wired using the "I" and the "S", was used for a dash "idiot" or "gen" light. Since you are going to be using an ammeter, you do not need the "gen" light unless you want it too(it is convienent for alerting you right away, especially if the fan belt comes off) Here's the diagram for the second way to wire it.



It's your choice how you want to wire it. It will work either way.

 

I hope this works, this is the diagram I have. It's a little different than yours. The distributor I'm using is and HEI one wire GM style distributor. The 'F' post on the alternator connects to the 'F' post on the regulator. It's hard to tell with the ford-trucks.com over the line. John

 

The only difference I see is the "A" terminal in your diagram is connected to the "S". This would work, but is not normally how it's done.

The "A" terminal on the regulator is the monitor wire for the regulator. It uses this wire to see how high the voltage level is in the system, and uses this info to vary the output of the alternator. They usually monitor the system voltage close the battery, hooking it to a heavy wire near the battery. Your diagram's way of hooking it to a small wire, which runs up into the dash through the ignition switch might work ok, but also may over charge the battery a little bit, since it would be monitoring the system voltage way down the line, far away from the battery. This may make the regulator "think" the voltage is lower that it actually is, and the the voltage at the battery may run a little high.

Another thing I see in your diagram is the starter solenoid has two small wires going to it. This is fine and proper for a points or duraspark II Ford system, but for an HEI one wire system, you do not need that wire running from the solenoid to the distributor. You only need the one wire running from the ign switch to the dist.

 

I've been reading about an alternator system using remote voltage sensing where you run the wire that senses the voltage to a junction box which in tunr is where the main "power-up" wires for all of your accessories originate from as well as the battery charging wire. The system is designed using a chevy alt., but would it work the same by running a wire from the "a" on the regulator to my junction box?

 

Yes that would work. But you still have to be careful how you manage the system with the wire sizes. For this to work well, you need to run the output charge wire and the "A" wire to the junction like you stated, and this junction needs a fairly large wire running from the junction to the battery, depending on how far away the junction point was from the battery itself.

You do not want the alt and the "A" wire not to "see" the battery. If this junction was far away, with a small wire running to the battery, the battery would tend to be too remote, and get "short changed" as far as the charging goes.

 

I would be running wire the size of welding cable from junction to battery. The junction would be within 2 feet of the battery mounted somewhere around solenoid. The wire from the alternator is already a heavy wire. Given that the wire from the "a" connection on the regulator is not real big I assume an additional length of wire the same size would suffice?

 

That sounds ok. And yes, the "A" wire can be a small wire. It's only job is to sense the voltage level, and it has very little current running through it to the regulator.

 

I thought of one other thing. By running the "A" wire directly to my junction would there be any possibilty of the system back feeding and running the battery down when the alternator wasn't charging. Would a diode need to be installed in the "A" wire?

 

No, that's all taken care of in the regulator. The key-on hot wire coming in on the "i" terminal or the "s" terminal(depending on which set-up you have) is what brings the system online and keeps it from running the battery down when the key is off.

You are not really changing anything from factory as far as how to hook the wires up. You are just changing their location in the system.

 

Thanks alot you've been a big help.

 

Have a 65 Ford F-100 just bought a 110 Amp Alternator and it says it has a "Internal Regulator". So what is the eaiest and best looking way to wire this things up? I want to keep the original wiring harness. I'll try and add a picture some that might help us sort this out. Thanks Vegasmax

Unable to post picture so here are the terminals on the back of a regular looking 65 Ford Altenator:

BATTERY TERMINAL (INSULATED)
GROUND POST/TERMINAL
"S" TERMINAL (INSULATED)
FIELD TERMINAL (INSULATED)

Can I just hook all of these up as before and eliminate the voltage regulator and make the wiring changes at the voltage regulator?

But, what changes have to be made?

I am running a "Volt Meter" and a "Charge Light" (original)

Thanks guys I know this is simple but I want to have some expert advice to avoid any "Smoking" issues....thanks Vegasmax

 

Is this a aftermarket alternator? If not, what is the alternator originally made for? What's throwing me a little bit is the field terminal. If the alternator has a internal regulator you do not need the field terminal unless it's there just for troubleshooting purposes. I do not see a terminal to connect to the ignition switch also, to turn the alternator on and off unless it does this automatically(some "one-wire" aftermarket alternators work this way).

 

Yes Sir; It is a aftermarket Alternator and not instructions provided and no support offered. I do not know if all the wires are required or not. In the above post I made I took the info stright from the seller's ad where it states it has a Internal Regulator. I am very confused but I do not want to wire it wrong the first time out. Thanks Ron

 

Ford Factory Chrome Alternator GM 110 AMP 3 Wire the ads says???