Thought I would run this by you guys. I have a long water pump setup, except I will be replacing the water pump with a proform electric water pump. I am curious how big of a crank pulley you guys would recommend I run. I am converting from a short water pump setup, so I will have to buy a crank pulley again. This is a non-serpentine setup- just alternator and crank pulley. I am curious what size I should shoot for. This is a street/strip setup.

Thanks guys.

 

It doesn't really matter the size since it's only driving the alternator. As long as it's large enough to keep the alternator spinning fast enough to charge while at an idle that's all you'll need. Is the alternator pulley stock size? Too small a crank pulley will underdrive the alternator.

I use a larger underdrive pulley on my alternator and a factory size crank pulley. It's a 6 rib serpentine belt. Once I got the alignment problems fixed everything works fine. The alternator charges at an idle but I'm not sure how fast the alternator is spinning when the engine is at 7000 rpm. With proper alignment, a serpentive belt is better than a V-belt.

Go to the junkyard and measure a bunch of pulleys. Find a small one that will work and bolt it on (3 bolt pattern). I'm not sure how many choices you're going to find with a V-bent system. If the alternator has problems charging at low rpms, go find a larger crank pulley.

My truck has only the smaller crank pulley. At an idle when lights, heater etc are on, the voltage really drops off.

 

Thanks Stephen, that is what I was worried about is idling now that I will have an electric water pump. Thanks for the info.