Djs94stang

I just put on a set from Steeda (asp racing pulleys reboxed). I installed all 3, crank, wp, and alt. I haven't measured the voltage yet but even without any extra electrical items the voltmeter drops a bit when idling. If I put the headlights on...they dim noticeably at idle and with the brake on (brake lights)..it drops more. Add the blower motor/ac and the volt meter drops a lot. The battery light never comes on but I don't like it.

Has anyone else experienced this....and do most just leave the alt pulley stock? Oh yeah...and the alternator is fine otherwise.

Demon_Mustang

No, don't use the stock pulley, because the stock pulley is bigger than the one that comes with the underdrive set, which would make it turn even slower. The alt pulley that comes with the set should be smaller, or an "overdrive" pulley to compensate for the smaller crank pulley. If not, then whichever one is smaller, put that on the alternator.

Djs94stang

I have a 94...it may be different than the 86 to 93's. My stock alt pulley was 2 inch and the one that came with the kit was 2-1/2 or 2-3/4 inch. Anyway...you answered my question...I'm going back to the stock (smaller) pulley. I think other than the crank the water pump pulley is more important....thanks.

Demon_Mustang

Yah, you should always stay with whatever is the smallest for the alternator, hell, you should even go buy yourself an overdrive pulley for the alternator to compensate. But I guess see how the stock one goes, and if it's still really low, then look into an overdrive.

Djs94stang

I switched back to the 2 inch for the alt. It's much better. I put a digital vm on it and it will drop below 12.5 volts when it is idling, with the fan on the 2nd speed, headlights on, rr def on. With the 2-1/2 pulley it would drop considerably at idle with just my foot on the brake peddle. Thanks for the tip about the overdrive pulley, Demon...I didn't know they could be purchased. I suppose if I find a problem with it now I could go down to a 1-3/4 if they make one.

vfast

this is why I always ungrade my alt when doing this mod