How many amp alternator do I need?

[thatK30guy]

For my '85 K30 with 454?

Not running anything extra but just the factory setup. Had to remove the alternator on the K30 when I sold the K20 as the parts stores were closed. Now I only have the junk one from the K20 for a core but saw on Napa online site literally hundreds of different amperages and sizes.

What do I look for?

 

[rampage]

Biggest amp consumers on your truck should be the headlights, radio, and heater/ac blower motor. I'd guess that a 60 amp should be plenty. Check the gauge of the charging wire first, that would be a good indication of the maximum size you can get without having to upgrade that wire.

 

[paratrooper307]

60 amp is about stock for a truck of that vintage.

Think about what you are going to do with your truck. If you are going to buy an alternator, you might want to get one with some room to upgrade. Power hungry accessories, such as additional/upgraded lights, stereo equipment, winch, inverter, electric fuel pump, fans etc etc can quickly overwhelm these older systems. The factory wiring is limited in capacity, but wiring is easy to upgrade.

 

[dremu]

Can't imagine as the highest-capacity stock type will be much $$ more than a low. IIRC you can get a 90-ish amp unit without changing the case and mounting, so just get the highest capacity available. As mentioned, check out your wiring and maybe replace the alternator-battery jumper, but that's easy & cheap.

-- A

 

[thatK30guy]

No winch, no extra added on stuff other than factory setup. Just a gas guzzling BBC truck so don't want the higher amp alternators which means more money to pay for. Just a KISS method.

 

[1-ton]

My 85 K30 Silverado (with 454) came factory with a 66-AMP alternator. I think was the highest AMP alternator there was for passenger vehicles (ambulances came with an 80 something AMP ALT). NAPA does carry a single wire 100 AMP ALT
PN# 213-4356SW.

 

[streetrodchev]

I have a 60 to 70 amp alt, on my K30 that I plow snow with. I have not had any problems with the alt. while running the snow plow pump (starter size motor) and extra lights. I do have dual batteries in the truck.