I currently have a AC Delco remanufactured alternator. It charges great except for under 1300 RPMs. It could be the volt gauge, but under about 1300 RPMs to volts drop to about 10.5 volts. This is without a major load on the alternator. Since my stock pulley is 2.5" in diameter, would going to a 1 7/8" diameter pulley solve my little problem?
Thanks

 

I use a smaller pulley for my alt cause of my stereo. It helps a bit, but I doubt it will solve your problem. Sounds like you need a higher amp alt if you can't hold 13v with no load at idle. Easy ratio = If its ok at 1300rpm, then it'll be like that at 975rpm (1300 x 1.875 / 2.5 = 975)

 

hmmmmm, sounds like in a perfect world(me having more money) i could get a higher amp alternator and this pulley. i will probably get a new pulley though anyways. what is the possibility that my gauge is wrong. because i remember my gauge reading 10 volts one time but my battery had 13+. (this was with my 800 watt amp pulling juice as well as headlights and electric fan)

 

Give the pulley a try. Be sure to get a high quality belt for it. Since the pulley is smaller, there is less surface area for the belt to grip and the cheap belts tend to slip and squeel easily.

 

thats for the advice.