Under-Drive Pulleys

[ar0ck]

While at a garage today replacing a stripped oil-pan bolt the tech told me that my serpentine belt is on its way out. So I thought to myself what an awsome time to sneak in some performance parts. But heres my question:

If I were to buy a Under-Drive Pulley Kit would the replacement belt just be a regular GM type? Or is it anything special?

Obviously the pulleys would be put on at the same time as the belt.

[deadtrend1]

The new belt you can get at any parts store, you just need to know what size to get.

Depending on the pulleys you get, you can run a string or something to get the approximate size you need. I believe the two piece March underdrive setup (Alternator/Crank) requires a 59 inch belt. SO you would need Dayco number 590K6.
590 = 59.0 inches k6=6 rib

If you just get the March crank pulley only, then I think its a 59.5 inch belt. So 595K6 would be the Dayco part number on that.

[GP99GT]

The new belt you can get at any parts store, you just need to know what size to get.

Depending on the pulleys you get, you can run a string or something to get the approximate size you need. I believe the two piece March underdrive setup (Alternator/Crank) requires a 59 inch belt. SO you would need Dayco number 590K6.
590 = 59.0 inches k6=6 rib

If you just get the March crank pulley only, then I think its a 59.5 inch belt. So 595K6 would be the Dayco part number on that.

those are old dayco numbers as far as i know, at my work its 50xxxxx...5060590 would be 6 groove 59 inch belt...5060595 would be 59.5...5070590 would be 7 groove 59 inch.. and so on

[EVIL90SS]

save your money and get a stock pulley, underdrive pulleys are worthless

[deadtrend1]

save your money and get a stock pulley, underdrive pulleys are worthless

I'm actually with him, all i noticed on my 91 was that my lights dimmed at a stop with my radio cranked.

[j0n]

i have em and havent noticed any loss in charging power and the motor seems to spin up a lil quicker

[BigAls87Z28]

I am also agaisnt them. Waste of time money and effort. The 200 or whatever could be spent on something else, or save it and spend it on something later on.

[j0n]

i paid less than 100 for a used set in mint condition and they came with a belt in great shape