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Discussion Starter · #1 ·
Well, I had a so-so weekend. Drove in to Houston on Saturday for my folks birthday weekend and noticed that my voltage gauge was reading below 12v. I put it off until the next day and tried to start her up...no luck.
I ended up charging up the batteries via my dad's charger and drove her over to Autozone where they confirmed the fact that the alternator was not putting out any voltage. So, armed with my cross referenced list of alternators off of 4btswaps.com, I asked to see if they had any alternators per my list. They didnt' have anything close. Ended up that Napa was the only place with one...and it didn't fit. The shaft diameter on my alternator is considerably bigger than the one Napa had. My AC compressor is run off of the alternator via a dual pulley (Serp and V-groove), so it was vital that I retain the dual pulley setup.
So I called every rebuilder in town to see if I could find someone to rebuild my current one and no luck, which makes sense since it was labor day weekend. Luckily, I was able to find a guy that just happened to be in the office picking up some paperwork. He was an old timer that has owned his shop since the 50's. He knew exactly what I needed because he used to supply the local Frito Lay's fleet with alternators. He said to not bother looking around anymore since the shaft size on the alternator is bigger than the ones found in auto parts stores. He told me to just buy a Chevy pickup alternator from 83-86 and swap out the backs. The alternator is a Delco 10SI model that puts out 79Amps. So I went to O'Reilly's and bought a $50 (plus core) alternator and swapped out the backs and kept the rotor and front casting. Autozone tested it out on their bench tester and everything now works great. I was sure glad I stumbled across that old timer this weekend.

My engine is a CPL 858.

Now to address the massive coolant leak I found this morning......
 

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Thanks for the information! That will come in handy in the future, I am sure.

I had a similar situation while trying to keep a Case-IH combine running on a sunny, dry weekend when the alternator went out. I swapped all the parts around up on top of the combine in about 10 minutes. I had a "good" pile of parts and a "bad" pile. My dad said if it worked he "would eat his hat". He was sure surprised when it did!
 

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Do you happen to have part numbers for the alternator(s), Pulley, etc? Pics would also be good.
 

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Do you happen to have part numbers for the alternator(s), Pulley, etc? Pics would also be good.
^Probably not unless you were a rebuilder for the Frito Lay trucks.

If the swap is as simple as pulling the back off, then you can use ANY GM 10SI alternator rebuild kit. You get a set of brushes, regulator, diode trio, etc. etc. for about $10
 

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I did the same with the help of a NAPA guy that was real sharp on Delco stuff. The part that's even nicer: keep the halves that are not used, then if you have a future failure you can reassemble to the parts store configuration and get a warranty replacement! GM Delco alternators often must be disassembled and 'clocked' at the parts stores to fit a particular vehicle's configuration. Because of that there's no questions about an alternator that has obviously been disassembled. From an ethical standpoint you are only returning the actual failed part that is covered under warranty, no real deception to me.

Thanks for posting this good tip, and glad you got her running again.
 

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^Probably not unless you were a rebuilder for the Frito Lay trucks.
I was thinking it might be possible to replicate as another option for putting AC in on a swap, thus wondering if he might have found part numbers on the alt. pulley, alternator (that has the bigger shaft to support said pulley), etc.
 

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Discussion Starter · #7 ·
I'll try to see if I can find the paper I wrote down the stamped part number on. If not, I have the contact info of the guy that worked on the alternators for Frito Lays.

http://www.aaaalternators-starters.com/
 

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Add this to the FAQ please :D
Ha ha, it was already done before your request! ;)

Additional information, there are "flat ring spacers" that will shim the shaft diameter from the smaller size to the larger pulley size. They look like steel wedding rings. I discovered them years ago when I was an alternator rebuilder. I would imagine they are still available.
 

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Discussion Starter · #10 ·
I asked the guy at NAPA about spacers but he said he didn't have any available.

Also, it looks like the thicker shaft is also a little longer than the conventional 10SI alternator due to the added length of the dual pulley.
 

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The spacers probably a rebuilder sourced item. I fabricated a 10SI from parts and have it mounted on a 6BT. I will attach a pic as soon as I have a bit of free time. The pulley was a standard 8 groove .670" bore but I had to use a spacer to shim the pulley forward for the correct belt alignment. This results in a small gap between the rear of the alternator pulley and its fan. It worked with the standard length 4BT CPL 858 belt. I think the rotor shaft length may be the same in both diameters. Different depth pulleys can give an optical illusion because of the lengths involved. I would have to measure a few before confirming this.
 

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Discussion Starter · #12 ·
Oh..yeah, I had a ring spacer on mine as well. I thought you were initially talking about a shaft adapter of some sort that would let me use my larger diameter pulley with the smaller diameter shaft.
 

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I thought you were initially talking about a shaft adapter of some sort that would let me use my larger diameter pulley with the smaller diameter shaft.
I thought that is what he was talking about.

ALL gm alternators use the ring between the pulley and the bearing, or else it won't spin when the nut is tightened.
 

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Ok, let me show what I'm talking about. Using "rounded dimensions" this is a pulley with an .875" bore setting on a .670 shaft. There is no way this is going to work at this point.
 

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Then what you have to do is get the right combination put together to fill the bore of the pulley and to space the fan and the pulley in the right location. Now the pulley becomes centered on the smaller shaft.
 

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Ok, let me show what I'm talking about. Using "rounded dimensions" this is a pulley with an .875" bore setting on a .670 shaft. There is no way this is going to work at this point.
Well, I'd call what would go in there a sleeve..

But that's just me.
 

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It acts as a sleeve but the trade names in the catalogs refer to them as:
"Drive end spacers"

Fan spacer;

Pulley spacer;

Rotor spacer

Those are the names I used whenever I was ordering them. ;)
 
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