Issue: Generator-to-Alternator Conversion
 

My generator started making noise from the front bearing. I am going to keep the generator and rebuild it. However, in the meantime, I purchased the basic 30-35 amp alternator conversion kit (6V positive ground).



Before replacing the generator with the alternator, I kill power to the car at the master cut-off switch which I installed right after purchasing the car. I then install the alternator and hook up the same two (2) wires that were on the generator to the single alternator post. Should be a simple swap... When the installation is complete, I turn the power back on at the master switch but the car instantly blows the 30 AM fuse. (Fuse that sits on top of the starter.)



I cannot connect the wires to the alternator without blowing a fuse. "Houston, we have a problem." (Obviously I have not had a chance to start the car.) The car is 6V positive ground and there are no bare or broken wires. I then switch the alternator out with another alternator thinking the alternator is bad. The same problem still exists...



So far, I have reviewed in detail the Wiring Diagram provided by MAFCA. The previous owner of my car has the Coil wired differently. The Black Wire from the Coil is connected to the passenger side of the terminal box rather than the driver's side of the terminal box. The other wire on the Coil runs to the ignition switch.



I am going to switch the wires to reflect what MAFCA represents as the correct way to wire the Coil.



Do you all think this could be the problem with blowing the fuse?



Thank you for your guidance!
Brent

Re: Issue: Generator-to-Alternator Conversion
 

It sounds like the wires connected to the alternator are on the wrong post. A picture of the rear of the alternator would help.

Re: Issue: Generator-to-Alternator Conversion
 

There was only 1 post available. See attached photo for reference.

Re: Issue: Generator-to-Alternator Conversion
 

You have a short somewhere. Since both generator and alternator are positive ground should not be a polarity issue. If the alternator is a negative ground and battery is hooked positive ground that could cause the problem you are seeing. Put the generator back in and hook up. If fuse does not blow and when you connect the alternator it does, then the alternator has the wrong polarity.

Re: Issue: Generator-to-Alternator Conversion
 

The thing with the terminal box is probably not the source of the problem, that was a change made midway through production to place the ammeter inside the ignition circuit. Does sound like a short somewhere though.

Re: Issue: Generator-to-Alternator Conversion
 

I did hook the generator back up and No fuses were blown. I then replaced the alternator with another positive ground 6V alternator (thinking the 1st alternator was bad) and still have the problem. I will continue to search for a short somewhere but geeze...doesn't make sense!

Re: Issue: Generator-to-Alternator Conversion
 

Re: Issue: Generator-to-Alternator Conversion
 

Any chance the battery is installed negative ground, the generator wont care
but the alternator will.

Re: Issue: Generator-to-Alternator Conversion
 

Rechecked the battery connection. Confirmed that it is Positive Ground.

Re: Issue: Generator-to-Alternator Conversion
 

So touch both wires together, if fuse doesn't blow it's not the car, now touch battery wire to alternator, if spark/short problem is in alternator---- most likely it is negative ground, most + conversions use negative ground parts and add a post and ground strap to make conversions, this way a standard diode set is used and instead of grounding the diodes to the case a negative post insulated from the case is installed, and a metal strap connects the original positive post to ground.

Re: Issue: Generator-to-Alternator Conversion
 

From the picture, it sure looks like the wire leading off the alternator into the Main Light Harness is in less than beautiful condition. It may be the picture but it looks like a "fire waiting to happen". I'd disconnect that lead wire to the light harness first and see if the problem goes away.
Beware, alternators are controlled electronically and can be much more sensitive to bad wiring in other parts of the electrical system. As such, if your safety fuse doesn't suspect a short and blow, the inner workings of the alternator will can sustain damage. I've had this happen to a customer who hooked up signal lights with obvious issues in running wires through and around the chassis and firewall, only to "fry" a brand new alternator.

Before you get crazy, try and eliminate items one by one. in this case, it's very simple to take the lights and the horn out of the equation.

Re: Issue: Generator-to-Alternator Conversion
 

I'd suggest that you disconnect the wires from the alternator, start the engine, touch the wires, one at a time, to the terminal on the alternator and see what happens.

Re: Issue: Generator-to-Alternator Conversion
 

I am going to expand on what Katy said. Unhook the wires to the alternator and start the car. Then measure the voltage at the alternator terminal to see if it is negative 7.5 volts or positive 7.5 volts. You may have fried the alternator in which case it may be zero volts. The alternator may require a load in which case hook up the wire to the light switch and turn on the lights.

Re: Issue: Generator-to-Alternator Conversion
 

The alternator has same front bearing as generator

Re: Issue: Generator-to-Alternator Conversion
 

Problem sure smells like wrong polarity alternator. Do as nkaminar says and check voltage with wires removed/insulated. You want a negative voltage out. You need to rev the engine to get the alternator started.

Re: Issue: Generator-to-Alternator Conversion
 

Update: I inspected all wiring from terminal box to instrument panel. All wires look good and correctly hooked up per the Ford Wiring Diagram. I then replaced the "terminal to generator" wiring harness with a new harness because it had a little wear and tear on it.


Trying trace a potential short, I only hooked up the 1 wire from the new terminal to generator harness. I did not hook up the wire from the "light harness." Same issue occurs...blew the fuse.



I believe this alternator may be bad/incorrect.



Thank you everyone for your guidance.

Re: Issue: Generator-to-Alternator Conversion
 

Did you measure the voltage at the terminal on the alternator without any wires being hooked up? Look to see if it is positive or negative.

Re: Issue: Generator-to-Alternator Conversion
 

On another discussion, RotorWrench has a link to an alternator rebuild and conversion kit to convert to positive ground, 6 volts.

https://www.ebay.com/itm/10SI-Delco-...6606664?_ul=IN