my car now has underdrive pulleys and horribole charging problems. aside from the fact my alternator may be going bad too i need a new one and wont go less than 180 amps but i cant find one anywhere. jegs and summit stop at 140 and i cant find anything bigger can someone point me in the right direction. and what specific type do i need? is it the gm one wire hook up?

 

What exactly have you underdriven? Why not find an overdriven alternator pulley?

 

i dont know if ive heard of an over driven pulley. i had the crank and alt underdrive pulleys but had to switch back to the stock alt pulley because of the severe charging problems. i still need a bigger alt, im sure mine isnt tip top anymore but just cant find a 180 amp to fit.

 

What alt. do you have now?

What pulley kit did you get?

What percentage underdrive?

 

as far as i konw ive got the stock 105 amp alt that came stock on the car. the underdrive pulleys i know really nothing about, bought them used on here. actually a waste of money...

 

Well, you know the sinlge most important fact about them then, at least, on a street car.

 

lol, live and learn i guess...

 

 

check out alternators.com i have a new delco 140 10si in my car, works great!

as far as pulleys go, take your current pulley to a alternator rebuil shop and they should be able to give you a smaller one. many severe duty GM applications use smaller alt pulleys.

 

I had my 200 amp one built by www.4alterstart.com

 

Depending on the ratio of the pulleys, by switching back to the stock pulley you may have slowed down the alternator rotation.

I know my march pulley setup was smaller for the crank and waterpump, but it was a larger pulley for the alternator to make up for the smaller crank pulley. It keeps me above 12v at idle (usually 12.3-12.4), and as soon as I bring the rpms up above 1000rpm it shoots to 13.8-14.2v. Still not optimal, but definately keeping a charge in the battery.

Measure the diameter of the drive pulley (crank) and divide that by the diameter of the driven pulley (alternator). Then increase the size of the driven pulley until you get a ratio close to stock. That should get the alternator RPM's back up.

Oh, another issue to worry about doing the pulley intermixing. The backspacing may be different between stock and aftermarket, making you throw belts. IIRC my new pulleys stick out approx. 1/8" further than stock ones. Probably to make them more universal.

Good luck with it

 

Right concept, but you've got it backwards -- increasing the size of the driven pulley would slow the alternator RPMs down.

Guess you haven't ridden a 10-speed bike in awhile, eh?

 

lol, not in like 6 years

Thanks for catching that, it was late and I was tired... (and wrong )