Alternator advice please

[Stocker]

The original alternator in my '72 K20 finally seems to be failing. It still works, but is starting to sound like a miniature rock crusher. A mechanic told me it will need to be replaced soon.

So far I have searched the board and checked a few online vendors, trying to figure out what I need. Most of what I found so far are remans, and most are rated from about 55A to about 63A. I just added a couple pusher fans to help the A/C but other than those, it's stock.

Tomorrow I'll try to determine what the factory alternator rating is. If a 63A reman Delco will work, that should be easy to find locally. Is there any reason to get one that's rated higher (more amps)? The stock one has served me well for a lot of years.

[brown7373]

You should be able to find one with more amps, or your original can be rebuilt with higher amps. Most areas have places that can rebuild them. I don't know how much more you need, but I have friends that added electric fans and needed to upgrade the alternator.

[leddzepp]

Take your existing alternator to a local shop and have them rebuild it. Tell them your amperage requirement and they can wind it to suit your needs.

[HO455]

Going the local rebuilder route will get you a completely rebuilt unit with all new bearings instead of bearings that passed a go/no go test that you get with parts store rebuild/remanufactured units.

[Stocker]

OEM appears to be 61A. Adding the draw from the fans brings it up to nearly 80 amps.

I'm not aware of any rebuilders in my small town but I'll ask around. Nearest sizeable town is about an hour away and might be my best possibility.

[Already Gone]

Originally Posted by leddzepp

Take your existing alternator to a local shop and have them rebuild it. Tell them your amperage requirement and they can wind it to suit your needs.

After checking out everything and thinking of the trucks usage I di the local rebuild thing with mind.

[Stocker]

It's been a few days so here's a quick update. There are no local rebuilders. The only place I found an hour or so from me said they mainly do big industrial stuff -- it's not worth their time to rebuild automotive alternators. So I ordered a new 80A from Summit. It's built in Ohio, not in China like so many others. UPS delivered it the next day and I installed it that afternoon. One more little problem out of the way!

[Mike C]

I would put a 10si alternator on it. Buy one from Rock Auto brand new for about $75. Get a conversion plug that goes right onto your stock external regulator wiring harness. Done.

[Stocker]

Originally Posted by Mike C

I would put a 10si alternator on it. Buy one from Rock Auto brand new for about $75. Get a conversion plug that goes right onto your stock external regulator wiring harness. Done.

I checked Rock Auto before I bought from Summit -- they were all remans near stock amperage except one new at $79 (doesn't say where it's made, maybe China?) and its amperage is not listed.

The one I bought has a 10si case with 10dn internals to work with my external regulator. No conversion plug needed.

[Mike C]

Most replacement 10si alternators are 63 amp. I bought a couple of brand new AC Delcos recently.

The point of going to the si is getting rid of the mechanical regulator and going solid-state in addition to higher output. Not sure why you would put guts from an externally regulated alternator into an internal one?

They have different rear cases due to the plug and you wouldn't want to confuse the two...

a 12si is the same physical size and many of them are 105 amp. Same thing with using the plug in adapter. I would replace the charge wire with anything over 63 amp.

[VetteVet]

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Originally Posted by Mike C

Most replacement 10si alternators are 63 amp. I bought a couple of brand new AC Delcos recently.

The point of going to the si is getting rid of the mechanical regulator and going solid-state in addition to higher output. Not sure why you would put guts from an externally regulated alternator into an internal one?

They have different rear cases due to the plug and you wouldn't want to confuse the two...

a 12si is the same physical size and many of them are 105 amp. Same thing with using the plug in adapter. I would replace the charge wire with anything over 63 amp.

The 71s and 72 and maybe some late 70s came with the SI case but were externally regulated.
The plug-ins look like this I I not like the SI plugs, -- --.

Most of the auto parts stores give 5 year or lifetime warranties on their alternators. The conversion is simple but going to the CS is the better route. They idle with more amperage output and are more reliable than the external regulated models.

Here's a favorite conversion thread of mine.http://67-72chevytrucks.com/vboard/s...d.php?t=567472

[Stocker]

Well, my limited knowledge is a direct result of my limited research & experience. I found parts-store remans rated 42, 55, 60, 61, 63, and 68 amps. I decided on the 80 amp unit from Summit because it has adequate output (considering my pusher fans) and is sold as a direct-replacement for my stock 61 amp alternator. It bolted on and the wiring connected without any modification -- so far, so good.