GM/Delco alternator pully

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brokeassyota

10 Year
Joined
Nov 18, 2013
Threads
13
Messages
94
Hello all!

My 60 has a GM alternator, single wire 100A. I have to replace it, the post to the battery broke. At any rate when I took off the pulley to swap to the new one I discovered it is the wrong size. The pulley is 2-3mm larger than the shaft. It is also not quite wide enough for the V-belt to seat correctly. The icing on the cake is that I think the pulley might be from a lawn mower, yup, lawn mower.
Does anyone have a part number available for the correct pulley?
Bonus if it is a smaller diameter than the questionable one I have now. The alternator I am replacing is 100A but I bought a 78A as money is tight. A smaller pulley will get me some more juice.
Thanks,
Adam G
 
Couldn't find a pulley at the part store. So I went to the old standby, Feldmans farm and home. Bought a pulley of the correct OAD, width and stand off, wrong shaft bore. Took the serpentine pulley to the tool store and bought the correct sized drill bit. Set up the new pulley in the drill press and drilled it out. Mounted up just fine, except the new pulley is not countersunk on the face for the washer and nut. So it is held on with a set screw. I am not a fan of this arrangement, but it will hold until I find a better pulley.
Gauge on the dash shows me charging at 14.5 steady, so that a win.
Adam G
 
Not sure on how common a mod it is. Pretty simple as long as it's done correctly. The previous owner of my rug did not do it correctly.
I just read a thread on here about using two stock alternators and an FJ62 bracket mounted in place of the smog pump.
Adam G
 
Find your local starter/generator/alternator repair shop. If more than one or you can't find one ask a big rig repair shop, a large fleet's repair shop, or even a large farm's repair person who does their work on these components. Ask more than one and get a consensus. My local guy has been an invaluable info and parts source many, many times. Without your location filled in no one can tell if their shop is also local to you too.

At the kind of RPM's that the alternator's shaft sees I'm thinking that the fit of a drilled hole is pretty marginal. I'll guess that 10,000-12,000 rpm at max crank speed isn't out of the question. For that you really want a reamed or bored hole with a tight tolerance fit on the shaft.
 
X2 on your local alternator guy. Mine got me set up with a Delco 2 wire 105 Amp alternator #728197-11 which cross referenced to a Delco alternator 321475 that I found on line. The pulley number from the on line source was called out as 1103, but my receipt from the local guy just says 15mm V groove pulley.

I know this is clear as mud, but maybe it will help.
 
That does help. Part numbers. Who'd a thunk it...
The fit of my "kustum" pulley is very tight. Just not happy with the method of retention.
Adam G
 
When I swapped a Delco alternator into my '84 FJ60 I was able to reuse the original Cruiser alternator pulley on the Delco alternator with no mods - remove one and install the other. Might not work for all Delco alternators but on the 21Si I used it worked fine...

Nick
 
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Another thing to add....
The shouldered nut was great because I was able to get a open wrench on it and hold the shaft with a allen wrench.

And because I'm anal and had visions of the nut coming loose projecting through my radiator, I tack welded one side if a washer to the pulley and bent the other side up to lock the nut in place.

I'll see if I can find some pics tomorrow.
 
The other direction for me is usually the Pull-a-Part. I take a cheapo digital caliper and some dimensions,
and start wandering through the appropriate makes of trucks.

But then, I enjoy wandering through the yards, too...

t
 
Little late but here's a pic of mine.

IMG_2225.webp
 
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