i bought an underdrive pully from march. it is soo much lighter than the stock pully which also acts as a ballancer i guessing?? do i need to buy some sort of dampner so i can use this pully or do i just bolt it up and drive it? and if so does anyone know the size of belt to buy with this crank and alt. pully kit from march?
thanks!

 

I wouldn't install it, i would just send it back and put my money into something that didnt slow down my accesories to gain 2 hp.

 

Sounds like its an "add on" pulley that is intended to sandwich between the stock damper and the hub. You MUST reinstall the stock damper if that's the case, or you run the risk of damaging the crankshaft. Without the stock damper, the bolts may also be long enough to hit the Opti.

There are integrated underdrive pulley/dampers made by ASP, and they are close in weight to the stocker, consisting of an inner and outer steel ring with a rubber piece in between.

 

I recently installed underdrive balancer from asp on my 96 lt1 and have asp balancer underdrive on my ls1. I have overdrive alt pulleys on both now. Even with no big stereo on the 96 auto I had to put the overdrive on. I guess if could have raised idle might have got away with it also.

I think they give a proven decent gain in the ls1 cars for sure but not much in the lt1 cars still the asp was a very nice looking piece of hardware and don't regret having it on. Its possible the car can rev a bit faster if it is truly lighter than stock.

 

well i found out that the old ballancer pully goes on after the march pulley. do the underdrive pulley not make any gains at all? or is it even worth it?>