3G 130AMP alternator upgrade

[Steves LX]

I upgraded to a 130 amp alternator last night. I noticed that when my headlights are on and the car is idleing my lights flicker a little bit and my voltage goes back and forth from 14-12 volts. If I give it gas it shoots to 14 and stays. Any ideas or suggestions on why and how to fix this?

[facemelter71]

was the alt' new?

[Steves LX]

yes bought it last night at KOL in Eastgate

[facemelter71]

The only thing i can think of is the voltage reg fluctuating.Did you upgrade the wiring?And do you have undrdrive pullies.

[Steves LX]

Yes I upgraded my wiring to 4GA wire and I have under drive pulleys

[IEATLT1]

under drive pullies would be your answer I'm guessing....not spinning the alt enough to keep the voltage up. I still can't understand why people run them on street cars.....

[5.0calypso93lx]

Yea, get rid of the underdrive pulley on the alternator. I only run the crank and water pump underdrives. I've got a 3g 175 amp on mine, and even with the stereo cranked, headlights on, gauges on, electric fan, I wouldn't even get a flicker.

[ibstrokin]

I would run all stock pullies, the reduced size of the crank slows the alt. as well. You drive your car alot and it runs great, you can afford 5 hp.

[Katmandu]

I just did the 3G alt upgrade recently as well. I also installed a underdrive Crank pulley. I have NO charging issues what-so-ever. :cool2:

I swapped out the stock alternator pulley with the 3G alternator pulley. This effectively OVER drives the alternator causing increased output at lower RPMs.

The 3G alt pulley is 50mm Vs the stock alt pulley which is 60mm.

Swap them out and see what happens.