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Discussion Starter #1 (Edited)
It has been my experience that if you ask classic Ford owners what things they want to upgrade on their ride, the answers you will receive will be varied. They may answer with a list of parts that will increase horsepower, improve handling, make the car look better, make the car safer, or any of the numerous other “improvements” that can be made to these cars. I find it interesting that seldom if ever, is upgrading the charging system anywhere near the top of the list. In many cases upgrading the charging system happens because our electrical needs out grow the current charging configuration, not because we planed for the upgrade.

Knowing when it is time to upgrade:
As with many things automotive there are several ways to know if your charging system is adequate for your electrical needs. The first and more inexact way is the observation of your headlights. If your headlights dim every time you slow to an idle, every time the stereo hits a loud low note, or they flicker as you go down the road at normal speeds than it may be a good time to look in to making some sort of upgrade. A more technical solution is to look at the output of the alternator and compare it to the amperage requirements of the electronics in the car.

On older Ford alternator the output of the alternator is stamped on the side of the alternator body. The stamping will be a number followed by the letter “A” which stands for amps, so a 35A unit would put out a max of 35 amps and a 60A would of course be 60 amps.

The amperage rating is MAX amps and is figured at between 5000 and 6000 RPMs so more than likely the alternator will put out less than that during normal driving use. Once you know what you have, the next step is to add up the amperage draw of the components. Each electrical device should have its current draw written some where on the component or in the instruction manual. Most likely you will see a number followed by “A”, “ma”, or “W”. “A” as we have already discussed stands for amps “ma” stands for milliamps and “W” stands for watts. If the product is rated in milliamps than it is not even worth worrying abut as there are 1000 ma in 1 A. To understand watts you will need to do some calculations:


So as an example of using the formula, I recently installed two 240 W electric fans in my Galaxie.

240W/12V=20A Using the formula tells us that that one fan draws 20 amps.

Once every thing has been converted to amps, the numbers can be added up.
40 Fans (Two fans drawing 20 amps each)
6 MSD (1 amp per 1000 RPMs calculates to a 6A max draw)
20 Stereo & amplifier
35 Factory electrical (original alternator rating to cover stock needs)
101 total amps

This means that I need a charging system that puts out about 100 amps. The good news is that 101 is a max amperage and average needs will probably be less, also the battery can supply extra power during high amperage draws and then charge during lower amperage draws. Even with that said I would recommend going with an alternator that is bigger than the estimated max needs so that the alternator is not being over taxed. Also by going bigger it allows you the flexibility to add future electronic components in the future should the need arise.

Upgrading from a generator to an alternator:
For some installing a new alternator is not based on power needs but rather a need to upgrade a factory generator that is no longer working. Ford made the switch from generators to alternators in the mid 60s. The alternator is the better technology and ford chose to switch to them in all their models because they were far more efficient. With that said those of you who have a generator in your car, such as I did on my 62 Galaxie, may want to replace it with an alternator, and that begs the question, what changes need to be made. Before you begin to do any part of the swap on the car, remember that any time you are working with your car’s electrical system the first thing that needs to happen is that the battery gets disconnected. This is done for both safety and to insure you do not damage any electrical components. Also, before starting any automotive wiring project there are two things in my opinion that you must have: a good wiring diagram, and a multi-meter.

In a situation like this, other references may be very helpful as well, such as a wiring diagram for a newer vehicle that came from the factory with an alternator. In my case I was lucky enough to find information on regarding upgrading a 64.5 Mustang Generator to a 65 stile alternator. This gave me something to start with and from there I turned to the 62 Galaxie wiring diagram I had, as well as the wiring diagram for an 84 Mercury Grand Marquis. (An 84 Mercury Grand Marquis I parted out donated the replacement alternator regulator, and wiring.) This gave me the info I needed to make the swap and I took that info to create these drawings. The first one is specific to my 62 Galaxie.

And the second drawing is specific to the Grand Marquis.

By having both pictures I was able to easily compare and see what needed to be hooked up and where to hook it up and I used the drawings to locate and disconnect the battery wire, charging light wire and accessory wire from the system. As you are dealing with disconnecting and removing unneeded wires one trick is to completely unwrap the wire bundles between the Generator or Alternator and it corresponding regulator and then separate the wires related to the charging system from the wires not related to the system. Once you do this the wires that need to be disconnected can be easily located and the Generator or Alternator and it corresponding regulator should come out attached, which allows you to remove wires you will not be reusing, all at once.

Aside from electrical hookups, for some there will be an issue of a mounting bracket for the alternator. In my case I was not only swapping out the generator for an alternator but also the motor, and the 302 I was putting in the car came with its own bracket and alternator, so there was no bracketing issues. For those putting an alternator on a car that came with a generator the alternator will not be a direct bolt on and there are two options to fix this.

The first option is to fabricate your own brackets. On more than one occasion I have seen the original Generator bracket modified to work for the alternator but it did require some major modifications. For many, there is a second, easier solution, and that is to find the correct alternator brackets for the motor you are using. Both the SB ford (289, 302, etc) as well as the FE series motors were available before and after the switch from generators to alternators, so all one has to do is get the correct bracket for their application.

The 60 amp alternator that replaced the factory Generator in my 62 Galaxie served me well for several years, but as I have made improvements to the car my electrical needs increased. The “upgrade” that put me over the top was as I said before, the recent install of two 14” electric fans that draw 20 amps each. There was no way the 60 amp alternator was up to the challenge.

The solution was a 1-wire130 amp Mr. Amp alternator from Performance Distributors While being similar to the 3G alternator that ford put on the 95-96 Mustangs The Mr. Amp alternator has the added benefit of a 65 amp output at idle where the 3G unit is 15 to 20 amps. Another advantage to the Mr. Amp alternator is that it came with everything I needed to hook it up.

My battery was already disconnected, so the first thing I needed to do to install the Mr. Amp alternator was to remove the old one.

As mentioned above with the Generator to alternator swap, I unwrapped the wire bundles and freed up the wires running between the alternator and regulator. Once I disconnected the battery wire, accessory wire, and charging light wire as well as unbolted the alternator and regulator I was able to remove the old parts.

The Mr. Amp kit comes with a thermal fuse to be put in line between the solenoid and the alternator. I chose to mount the fuse in the place where the regulator was before I removed it. The sheet metal on the inner fender had a very slight curve to it and I did not want to damage the fuse by tightening it down on to the shape of the sheet metal. As a solution I cut a piece of innertube to go under the fuse. The rubber flexed and squished which allowed me a snug fit with out distorting the fuse.

With the old alternator out, I took a quick comparison of the old one and new one. The Mr. Amp unit had the same mounting tabs but the body was a little larger and the pulley was also bigger.

These were good things to realize before I attempted to install it, as it made me aware that the new one may not fit quite the same as the original. Realizing this I did a test fit and the alternator slid right in to the lower mount and the upper hole lined up with the adjustment bar so I thought I was home free, until I tried to install the belt. Due to the larger pulley and some clearance issues between the alternator and the lower mount I could not move the alternator far enough down to get the belt over the pulley.

To determine where the fitment issue was, I moved the alternator back and forth along the adjustment bar paying special attention to where the alternator was hanging up on the lower mount. Once I determined where the clearance issue was I used a file to remove the extra bracket material, which was an easy but slow process. As I was modifying the lower mount, I did many test fits to insure I did not remove too much metal. As you can see from the before and after pictures quite a bit of material had to be removed.



Once I had the alternator fitting the way I wanted it to, I removed it so that I could connect the power lead to the alternator. The power cable provided with the alternator is some heavy wire and will work well for this application, however due to the position of my alternator on the motor and my routing needs, the wire provided was not long enough.

This was not a problem as I had some welding cable that I had left over from my starter upgrade and being that it was better than what came with the alternator I new it would be perfect to connect the alternator to the thermal fuse.

Keep in mind that one of the most important things when upgrading an alternator is to make sure you use wire good enough for the high amps it will be carrying. It needs to be heavy gage, and the more strands it has the better it will work. This is why welding cable is so good for this application, as it is very finely stranded and comes in many heavy gages. As you can see in the picture the black welding cable is at least twice as good as what came with the kit.

After taking some careful measurements I crimped the provided ends on to the welding cable and attached it to the alternator. I then reinstalled the alternator on to the motor, installed the belt on to the alternator, and attached the cable to the thermal fuse. A few more measurements and some crimping and the cable that came with the alternator was ready, so I installed it between the thermal fuse and the solenoid. I then crimped a new end on to the accessory lead in the car and attached it to the solenoid side of the thermal fuse.

With that connection made I had the alternator hooked up and it was time for a few quick checks.

The first check I did was to use my meter to insure I had continuity between the alternator output terminal and the solenoid. After that checked out I made sure there was not a short between the solenoid and ground. From there I was ready for the “smoke test.” The term “smoke test” comes from the electronics industry and is used to describe when you test a circuit for the first time by putting power to it. If something is incorrect on the circuit it will literally smoke in a matter of seconds. I find the term fits well here sense we are working with electronics and the amount of amps being provided by the alternator could make a whole lot of smoke if it was hooked up incorrectly.

Prior to firing up the motor I made sure that all my electronics: fan, lights, and so on, were turned off. I then turned the key and started the motor. Immediately I looked for “smoke” and listened for sounds that should not be there. All was as it should be. The next test was to attach the leads from my meter to the battery and see what kind of voltage I was getting. The reading was 14.62 V, which means the alternator was working and everything had been hooked up correctly.

You may be asking yourself why I simply did not use the factory charge indicator light on the Galaxie to let me know the alternator was working, for that matter why didn’t I mention hooking up the charge indicator wire when I installed the alternator. The reason is that this particular alternator, being a “1 wire” does not have a spot for the charge light. The regulator is internally configured to not need a light. This makes the install simple but does provide a problem if you want the factory light to work. I connected Performance Distributors via email and they were very helpful. The solution to be able to hook up the light is to replace the regulator with a stock unit for a Ford 3G alternator. I have purchased said regulator and corresponding pigtail and will get it installed in the near future.

As you can see the alternator looks right at home under the hood of my 62 Galaxie. I am very happy with the alternator I got from Performance Distributors.



206 Posts
Excellent write up!

Just to add to it, I thought I'd shed some light on the difference between what a "generator" does and what an "alternator" does. Essentially they're the same thing but different. (Yeah, I know that 'really' sums it up).

Both have a rotating field that generates an alternating current and voltage. (positive, negative, positive, negative..etc Or push, pull, push, pull). One the back side, there are slip rings and brushes. In the case of a generator, the slip rings are split so the brushes only pick up the positive. With multiple poles in the generator, we get an okay DC signal out of's a little choppy, but it works. The down side (this is were efficiency comes in) the negative signal is totally ignored/not used. That's where an alternator differs. An alternator does not have split slip rings, they're continuous. In this case, the brushes pick up the hole signal, positive and negative. The alternating current/voltage output then goes through a rectifier, which is a bridge circuit of diodes that lets the positive signal through as positve and inverts the negative signal to positve. So that's the mechanics.

Furthermore, lets look at output voltage. Without a regulator, the magnitude of the voltage would vary as the engine sped up and slowed down. (That'd wouldn't be good). This leads to how an alternator "makes" voltage. There is a rotor with windings that spins inside a stator with windings. If you just spin the thing, you'll get zero output. The rotor windings must first be excited with an excitation current. It gets this from the battery, but it's controlled by the regulator. The regulator is constantly sensing output voltage, as the rotor speeds up, the regulator reduces the excitation voltage in order to maintain that happy 12volts (okay, 14.7V..whatever). What really limits the alternator's output power (in Watts) is the quality of the insulative materials and the amount of copper in the windings. It's really all about heat. Generally, alternators are limited to 105deg or 130deg (depending on who's rating them) temperature rise over ambient temps. So in the example, the 35A alternator is rated as such because it reaches it's thermal limit at 35A, and respectively for the 60A model....that, and it runs out of excitation current to produce any higher power output (remember Watts=volts x amps, but only for single phase, 3phase is a little different).

Hopefully that sheds a little more light for those who were wondering.
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