alt. upgrade

[bigr79]

Hey y'all got a 77 k20 p/u with a fresh rebuilt sb 350 and my alt. Just went out on me....I remember looking it up awhile ago but cant remember where but I read it that there is a newer year of truck with a 120 or 130 amp alt. That will fit right where the stock 85 amp alt. Sits....wondering what year it was? And Wether I will have to have the v belt pully replaced on to it?

[VileZambonie]

http://www.novaresource.org/alternator.htm

[Irish_Alley]

yours 64 amp
http://www.autozone.com/autozone/parts/Duralast-Alternator/1977-Chevrolet-C10-1-2-ton-P-U-2WD/_/N-inbqzZ93xme?counter=1&filterByKeyWord=alternator&fromString=search&itemIdentifier=333351_23521_4676_
direct replacement if you can deal with 94 amp
http://www.autozone.com/autozone/parts/Duralast-Alternator/1986-Chevrolet-C10-1-2-ton-P-U-2WD/_/N-ij11lZ93xme?counter=4&filterByKeyWord=alternator&fromString=search&itemIdentifier=82360_188704_4678_
just swap the pulleys. they should have the tools there to do it

[78 Chevyrado]

I bought this one a year ago or so and it still works great.  runs my amp, e-fans, headlight harness, ac and wipers and the gauge doesnt budge.

http://www.dbelectrical.com/p-4516-high-output-chevy-3-wire-alternator-140-amp-65-85.aspx

and its a 3-wire so it will work correctly.  just stay away from one wire alternators, without remote voltage sensing, you will lose voltage.  they are a band-aid fix at best.

you will have to upgrade your wiring for the added Amps.

[bigr79]

I understand that it would be easier to just buy a brand new one but I'm lookin to go a lil cheaper route and hit a junkyard that has the newer style alt. Just need to know what year I need to look for? Swapin the pulley will be easy by the looks of it just need to know the year?

[Irish_Alley]

if you go to new they moved the alt to the other side and flipped the connections around think it was with the tbi engines, then they also moved the connections a little. do you have ac?

[78 Chevyrado]

for stricly bolt on replacements, get one off an 83 or later truck,  but theyre limited to 85A or so.

The New one your thinking of is a CS130 alternator, youll have to buy an adapter harness and modify your brackets for it to work.  i think that alternator is off of 1991 and later trucks ONLY.

Vile's link above will tell you everything you need.  otherwise you're limited to about 85A with a 12si alternator.  right now you have either a 10si or 12si.  they swap out and are bolt in.

My 78 truck came with a 63A alternator and it wasnt enough so I got a new one from the parts store, for an 83 model.  that gave me 78a or 85a, cant remember which.  that was enough till i added an amp and e-fans.