If you want to sell your old OEM pulleys, I'm an OEM pulley buyer. Seriously.

You can still sell your old alternators as cores, or if the diodes are still good, as used but useful alternators on craigslist, fitting a variety of Ford car (Mustang, Cougar, Windstar) and truck applicatons, without the pulleys. The buyer can swap in their own pulley from the alternator they are replacing.

 

For Y2KW57, Tugly and any other electrical experts, this is an electrical question pertaining to alternator to battery wiring that is potentially relevant to this thread.

On our vintage trucks, the 12V+ alternator output is directly connected to the passenger side battery. There is then a B+ cable that runs over to the DS B+.thus placing them in parallel which doubles the amps.

Would there be a problem with running an additional cable from the 12V+ alternator output to the DS B+ while leaving the factory wiring in place?

This will assist in settling an ongoing debate.

Part of the reason for the question pertains to using a HIGHER AMP alternator (190 AMP and UP) and the requirement to upgrade wiring to a heavier gauge when using these alternators to prevent a fire.




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A lot of people do this. But they also make the new cable from the alternator to the battery stop for a visit with some type of inline mega fuse first, before reaching the battery... not a direct connection.

Since current flows through the ground just as much as it flows through the positive cable, some people also add additional ground cables from the alternator case to the vehicle frame, and or to the negative battery post, or to a ground zone (a point on the frame that is near to, but not exactly the same point as, the point where the negative battery lead grounds to the frame).

I added a grounding strap from my lower alternator's case to the frame in a ground zone, near to where the negative lead on the battery grounds to the frame, and then continues on to the engine block.







The photo above is mine, but the photo below belongs to Springer Pop. You can see where he added a big thick red cable to his alternator. You can't see his fuse, but knowing Pop, he's got one on there somewhere before it reaches the battery. One interesting thing Pop has on his upper alternator is the B+ post extension for a lower alternator, which elevates the connection point for his cables to rise above the alternator somewhat. Usually, on a stock 6G alternator in the upper location, the B+ post is short and juts directly out the back of the alternator in an axial orientation (parallel with the rotor shaft), not a radial orientation (perpendicular to the rotor shaft). I'm not sure if this detail will help manage the addition of thick supplemental battery charge cable, but it is something to consider, as long as the hood closes without shorting against the top of the add on post.

 

Thank you for the reply. I was considering adding a 250A fuse to the project and mounting it on the DS fender well. Do you think the 250A is sufficient or too much? Is there a logical reason to reduce the amperage on the fuse to protect anything?

 

Yes. Reducing the fuse amperage will protect the cable, so the fuse will blow before the cable burns, catching other things under the hood on fire, like power steering fluid, which is directly under the alternator, or brake fluid, which is enroute to the driver side fender wall where you want to mount your fuse.

When you mount a hot cable to a fender, do think about how that fuse might be tested, installed, or removed and replaced by someone other than yourself. Let's say you fall ill for a couple of weeks, and are stuck in bed. Another family member, spouse, child, or whoever begins to use your truck to do the errands that you would normally do if you were well. One day, truck doesn't start for them, and they call a tow truck driver who just graduated high school, took autoshop, and knows everything there is to know about how to fix cars.

This guy, wearing his shining armor, pops your hood to see if he can find the problem, and voila, he spies your bright red cable, and follows it with his eyes to your fuse in the fancy clear holder... and sees that it is blown. Right away he thinks he's found the easy fix, and wants to pull the blown fuse out to show your stranded relative. In his haste, he forgets to disconnect the negative battery leads. Or, he remembers to disconnect the negative battery lead in front of him, but doesn't think to disconnect the paralleled negative lead to the battery on the opposite side of the truck.

One side of that fuse is always hot, blown or not. Does the fuse require tools to remove? Lots of aftermarket megafuses are retained by nuts on posts. If he over swings a wrench on that nut to free up the hot side of that blown fuse, will he accidently put a dead short between that post and the fender upon which the fuse assembly is attached?

These are the kinds of considerations I would give to an installation that involves several simultaneous safety considerations. It has to be fool proof, not just for me, but for any random person dealing with the vehicle in the event that both it and I become incapacitated.

 

It's been about 8 weeks since I've replaced my alternators and thought I'd let those interested as well as those that come across this in the future know how things are going.

The truck has been running great. There hasn't been any strange odors or unexplained fires even though the pulleys are the same size. When it's warm I'm at 14.4VDC, when it's cold I'm at 14.7VDC, and when it's hot I'm at 14.0VDC. With my old alternators you can subtract about .4VDC for those numbers. Last summer, on the hot days, I saw as low as 13.4VDC.

Even though the large case is physically larger (yes, I know, "DUH"), the pulley shaft seems to be located in the same position in relation to the mount. I didn't use a micrometer, just my uncalibrated eye while I held the old unit on top of the new one. The case seems to evenly swell around the shaft which is why I had to carve into the bracket for everything to fit. Also, the pulley seemed to fit about the same as before (the tensioner was in about the same place when I re-installed the belt), even with the washer shims for the upper alternator.

Also mentioned in an earlier post the OEM pulleys are different sizes between the upper and lower. I have talked with several more shops to get some kind of explanation why the OEM setup has two different pulley sizes and if there's any bad juju with having the same pulley sizes (like I do now). They all told me the same thing: it doesn't matter. No one has been able to tell me why the OEM setup has two different sizes...not even Google. EVERY electrical shop I've talked to can't tell me and say you can but there's no reason too. So I've taken their advice and just gone with it. So far so good.

I've been very happy with my decision with the alternators I purchased and how they are performing (even with the same size pulleys).

I understand that there's only a small percentage of us with more than one alternator but there's some info in this thread for everybody...hopefully.

Thanks to Y2KW57 for his curiosity, technical insight, and interest in seeing this run to ground.