3g alternator upgrade

Quick, simple answer: Put the stock pullies back on for best results


Long Answer: You can make the pullies work, but you'll need to make sure all the other systems are in good working order. The alternator charges based on RPM and outputs the required amperage as necessary. Alts have a min RPM to create a certain number of amps and each one is different. If you intend to run underdrives, you'll need to take the alt pulley and throw it in the trash. Then find the smallest alternator pulley you can find. ASP sells a 1 7/8". The small alt pulley will compensate for the underdriven crank. It might be enough of an RPM bump to allow for full charge at idle. You'll also want to make sure your cooling system is in tip top shape. Pullies don't cause the car to overheat, but they can expose weakness in the cooling system which will lead to overheating. Also, the lower RPM does mean reduced A/C performance as well (if you have functional AC)


With all that said, I ran UD pullies with an E fan and 3G130A alt for nearly 20 years without cooling or electrical issues. I was able to make it work, but in my latest rebuild I put the stock pullies back on. I was going for reliability over Horsepower. Better cooling and charging capability and AC performance are more critical to me these days