quick alternator question(pulley size)

i have a friend i believe is running an underdrive pulley set-up on his 89 5.0. and i'm sure its killing his battery, cuz he can push start the car once the battery has been charged for a while, but after driving it for a short while it dies.(i'm assuming the alternator isnt putting out enough juice to charge the battery)

here is a pic of his engine bay: http://www.torquecentral.com/attachment.php?attachmentid=14684
my question is, first off, is that an underdrive pulley? (he bought the car modified to where its at now) and second it looks smaller than a normal alternator pulley. to me. maybe i'm wrong. but the second question is, would putting on a stock size alternator possibly solve his problem. i'm going to go by tomarrow and check out how many volts the battery is putting out and test this therory.

but the thing that is perplexing me, is, if we were to put a stock, larger size pulley on, wouldnt that slow down the alternator and make less charge?

please inform me? thank you


~Steve

srothfuss said:

The real question that needs to be asked: Is the crank pulley stock or underdriven?

Click to expand...

so if the crank pulley is underdriven, that might cause the alternator to be spun too slow to charge?



~Steve