High Amp Alternator?

[GregL]

Hey guys,
Who offers a higher amp alternator for my '77 K20?
The standard 63 amp unit just doesn't cut it. It was new less than 2 years ago, but never an over performer.
I'm in the California desert with triple digit heat so I use my A/C all the time. With A/C on at night, my headlights look a little yellowish. If I turn my overheads on at the same time, forget it, turn signals will barely work then.
I'd prefer to buy made in U.S.A. new if possible, rather than a reman. There used to be a shop here that would rebuild for higher output, but they're out of biz now.
I refuse to buy chinese.
Appreciate any and all input.
Cheers, Greg

 

[fast 99]

63 amp unit should be adequate unless aftermarket items are on it. Has the system been checked, voltage, both AC and DC, battery, ect. We had tow trucks with stock charging systems, overhead and flood lighting, electric 8k winches for towing, and jump-started cars. No issues keeping up. Only modifications were an additional parallel battery and a smaller alternator pully from an Olds.

 

[mtnmankev]

If it turns out you need more amps, here are three choices.
American made.
Any good parts store should have what you want, but be prepared to shell out some good money and eat a healthy core charge.
Also, you will most likely need to do some modifications to your mounts.

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[75gmck25]

I used a mid 80’s rebuilt GM 94 amp 12si with v-belt pulley on my ‘75. It fits with no mods, although I chose to use a heavier gauge charge wire and run it directly over to the battery positive, I got the better charge wire with fusible link off a GMT400 truck.

 

[Shawn Watson]

Mechman seems to have some nice stuff. I'll be going with one of their 240 amp "quiet" units to keep the Holley EFI happy and power the stereo. I also don't know if the Vintage Air unit will warm up at idle speed so I'll have some juice if an aux a/c fan is needed. https://www.mechman.com/


Shawn

 

[Matt69olds]

Get a alternator for a late 80 Camaro/caprice/etc a sbc and with A/C and rear defog. That should be a 94 amp.

A stock 63 amp should be enough unless you have a bunch of electrical accessories. Before doing anything, inspect, clean and tighten the cables. If that’s good, get a digital voltmeter. Put the POSITIVE probe on the alternator charge stud. Put the NEGATIVE on the positive post of the battery. Start the truck, turn on every electric accessory. Read the meter, whatever the meter is showing is how much voltage is lost in the charge wire. If it’s more than a couple tenths of a volt, you need to repair or upgrade tge charge wire

You can do the same on the negative side of the wiring.

 

[MikeB]

Before buying another alternator, check voltage at the alternator output terminal (the one with the largest wire). Do it with the engine running with hi-beams and AC on. Then check voltage at the battery. The voltages should be close to the same, a little less at the battery. The ideal number is 14.2 volts, but even 13.5 at the battery is OK with old OE wiring.

Now check the voltage at a couple headlights. The connector must be plugged in, but you can pull it out a little to get a probe in there. If it's more than 1.0-1.5 volts below battery voltage, then you have resistance problem, not an alternator problem. That's probably one or more bad connections along the way from bulkhead connectors to fuse panel to headlights.

An extreme example is the stock wiring on an 82 C10 that I used to own. Battery and alternator voltages were around 14.0-14.2 volts, but voltage at the headlights was literally around 11 volts! That was a 3-volt drop due to resistance in the wiring and connectors. After installing a AAW wiring harness, the headlight voltage jumped up to almost the same as battery voltage! The headlights themselves were MUCH brighter and whiter. Same for taillights, brake lights, and dash lights. Even the heater blower ran faster!

That was with a 60-something amp AC Delco alternator. The max current draw I measured with high beams, brake lights, and heater blower on and radio cranked up was less than 40 amps, so a high-amp alternator would not have been the answer. And if you do get one, make sure the charging wire(s) from alternator to starter is large enough to handle the current. As I recall, my 82 used a metric wire roughly equivalent to around 11 gauge. As an example, an "EZ Wiring" kit I installed on a friend's car suggested running two 10 gauge wires instead of one from alternator to battery (or starter BAT terminal) if the alternator was more than 100 amps (or maybe 140?). But again, the major concern with original wiring is the connections.

 

[Mr. Goodtool]

Powermaster alternators are made in the USA. I'm running one in my 1975 C20 with a vintage air a/c system and ultra halogen sylvania headlights....no problems.

 

[BoxChevyDually]

PowerMaster, Mechman and Tuff Stuff all make upgraded alternators made here in the U.S.A., in multiple finishes and styles dependant on your needs. I upgraded to a cs144 style alternator that outputs 200amps, and the install was super easy, as they make a harness that converts a 10si or 12si style to cs144, so it's simple plug and play.

 

[GregL]

I went to Inland Alternator over here in Riverside and bought a 140 amp alternator from them for $125. Direct fit, cleaned up a couple of questionable body grounds, all seems to be good now. Thanks again guys.

 

[Camar068]

Don't forget DBElectrical. I've got an alternator and starter from them. Cheaper than OEM.

 

[SquareRoot]

I use Power master. They are super quality.