gmcman52

I have a 75 C3 that I'm currently replacing the L48 with a 383 motor. I have a Dewitt dual electric fan setup coming and I was wondering if my stock alternator will keep up with it 's charging duties. If not what amp would I need in it's place. Thanks John

derekderek

Take alt or car to get it output tested. Check numbers on alt to see if it is orig to car. Most rebuilts and aftermarket are higher output already.

Matt81

I would think we soon as you go electric fans, the original 60 (?) amp alternator is going to struggle. Add in headlights and I'd think battery would run down quick.

An easy and cheap swap is a CS144 alternator. Here is a write-up of my install with a minor problem i overcame. Very little invested in this upgrade and definitely happy with the final results. I swapped the alternator because I was fol!owing it up with a fuel injection install. Putting in electric fans soon so have plenty of power available.

terrys6t8roadster

I agree with Matt about the CS style of alternator upgrade, I didn't read his post but if the large wire on your alternator is only 12 gauge putting in excess of more than 100 amps isn't going to last. T

derekderek

And if alternator is original, either keep it or sell it in the parts section here. DO NOT turn it in for a 5 to 20 buck core...

Rescue Rogers

100 amps is usually more than enough. I have 100 amp with single dewitt fan, amp and subwoofer, and upgraded to halogen bulbs

carriljc

Just go to the CS-144. You'll be happier.

lionelhutz

You 100% need a bigger alternator. Go CS130D or CS144. Upgrade the charging wires to 6 gauge.

Do no try to use a C5 style alternator. It's connects to the PCM and is specific to a C5.

I personally wouldn't bother with any of the increased current 10SI versions because they still have the same limitations (cooling & idle current) that the stock 10SI alternators have.

gmcman52

Thanks guys for all the reply's. The alt is the orig 63 amp that I rebuilt some of the inner works in the 90's

jb78L-82

CS 144-140 Amp stock amperage alternator. Run a 6 gauge welders wire with an in line high amp fuse from the Bat terminal on the CS144 alternator along side the stock bat terminal wire to the starter. The starter to battery wire on my 78 is sufficient to handle a 140 amp alternator easily.