ripfirebird94

I have a 94 firebird formula. What is this? I found it in the back of my car. It looks fairly new I thought it was an underdrive pulley. Is that true? Is it stock?

BOLO

iTrader: (40)

Yes , it looks to be an underdrive crank pulley, in conjunction with the stock balancer when installed.

ripfirebird94

is it stock? i wanna know if the guy i bought it from or well the guy who traded it to the dealership i bought it from had it to put on later or if he took it off?

SS RRR

iTrader: (2)

Not stock. Probably a March brand U/D pulley.

ripfirebird94

so should i install it? and is it really easy to install?

BOLO

iTrader: (40)

Correct, not stock. And yes, you're probably right, it looks like a March pulley. I use to run one myself.

ripfirebird94

how are they?

BOLO

iTrader: (40)

Yes, as long as you're not running a high powered sound system in your car. And you'll probably gain 3-5 rwhp. Very easy to install. You'll also need a shorter belt.

ripfirebird94

how much is the belt, and what does sound system have to do with it?

SS RRR

iTrader: (2)

Think about it. It slows down your accessories including your alternator. Battery cannot charge effectively if there is a high demand.

jaysz2893

The Under drive Pulley slows down the accessoires (Power Steering, A/C, and the alternator) SInce the alternator is spinning slower it wont charge as good as stock. no big deal unles you have a big stereao that demands a lot of power. They do make a pulley for the alternator to compensate for the underdrive. I cant remember how much shorter the belt is. sorry..

ripfirebird94

its all good, and do i have to remove anything to get to the pulley or is it strictly a bolt on with hand tools?

RamAir95TA

iTrader: (2)

You need to remove the crank pulley and piggy-back the underdrive pulley onto it. Do NOT simply remove the stock pulley and bolt the UD in its place.

MasterTomos

iTrader: (15)

I've always wondered about finding a shorter belt for UD pullies...how is this done?

the_merv

iTrader: (88)

I used a 60" Belt and had no problems.

koolaid_kid

iTrader: (21)

The length is hit or miss unless you buy the kit. You can purchase one, such as the_merv did, and then swap it if it is too long/short.
The alternator pulley is a smaller pulley to make the alternator spin faster, is called an overdrive pulley, and I had to run one on mine. The battery died while idling at the track b/f I installed it, so I put it on and it was all good. All stock electrics, btw.
When I had the UD pulley and no OD pulley, I used NAPA part number 25-060598, which NAPA says is 60.4"
When I put the OD pulley on the alternator, I used DAYCO part number 5060590, which is a 59" belt.

95z286speed

iTrader: (1)

yep i also use the 5060590 belt, that looks like the same one i got and its really easy to install

AChotrod

iTrader: (17)

Looks like a BBK pulley to me. youll need longer bolts to mount it and a shorter belt.

RamAir95TA

iTrader: (2)

I just measured mine with a cloth measuring tape, then bought a few sizes close to it, and returned the ones that didn't fit.

SS RRR

iTrader: (2)

March recommends a 590 belt, however it is still a tad long so the pulley tensioner is not used effectively. If the A/C is still operational the belt may squeak for a few seconds after the compressor is engaged. If you use the U/D pulley it would be a good idea to use an alternator O/D pulley.