Installing a Underdrive crank pulley on my 91

[L98corvette]

Hey guys, how hard is it to install an underdrive crank pulley on my 91? I looked at it from above and it looks like a real pain, how do i get to the crank pulley? I know you would go under the car to put it on, but how hard will this be?

 

[sxyvet]

hi there l98 corvette,
i would also be very interested to know how difficult,how too and how long to change pulleys over?
are you changing all three pulleys over are you?
corvette central claim that bye changing all three pulleys you can gain up to 20 hp on l98 engine, do you thing that is close to the truth?
what tools are needed also to change them over?
may be a three arm flywheel puller i guess?
thanks
glen
sxyvet
australia.

 

[grumpyvette]

while I did change all three pullies and then installed the airpump eliminator, the net result was that the gains were minimal at best and the engine ran slightly warmer due to the water pump spinning slower at any given rpm.

(corvette central claim that by changing all three pulleys you can gain up to 20 hp on l98 engine)

while that might be true in limited cases Id suspect 2-4hp MAXIMUM is closer to the truth in most cars and that gains only likely at high rpms

look heres a dyno result on a similar mod

http://www.ws6.com/mod-2.htm

as to the difficulty, being an experianced engine builder and racer probably helped here but it took me under an hour, and was only mildly difficult, surely something the average guy can do in a saturday afternoon in the driveway as no special tools were mandatory that the average hot rodder won,t have access too.

don,t forget youll need a NEW serpintine belt

 

[sxyvet]

hi grumpy vette,
thanks for giving us some valuable info on the pulley kits!
do we need to pull much apart to be able to get the pulleys off though?
and what tool is best needed as well to do the job rite?
thanks
from glen
sxyvet
australia

 

[MBDiagMan]

It's impossible for me to know your skill level, but it is pretty easy to accomplish.

I have a two pulley that I put on my car probably 10 years ago and have never suffered any ill effects, even in heavy traffic in the Texas heat. I have made lots of small mods that have added up and my car is pretty quick for having an engine that has never been opened up further than the plenum and injector rails. A side benefit of this mod is that your accessory will last longer.

I have changed belts on a number of cars and I don't remember if the Vette is one that needs the slim tool for loosening belt tension or not. If I remember correctly there is room to use a 1/2" breakover on the tensioner to lever it up and remove the belt. I might be wrong though. You can get a tool for this job off the tool truck for about $30, or it might even be available for less at the parts house. Then changing the pulleys is a simple matter of removing the bolts and swapping the pulleys.

No, you don't have to go under the car and you don't need a puller. The crank pulley will come right off after the bolts are removed. Don't remove the large harmonic balancer bolt, only the three that surround it. You might have to tap on the pulley lightly to get it off.

On the alternator a strap wrench would be handy to hold the pulley while loosening the nut, but you probably could improvise with a rag and an extra large set of channel locks.

Good luck,

 

[G Winter]

On the alternator a strap wrench would be handy to hold the pulley while loosening the nut, but you probably could improvise with a rag and an extra large set of channel locks.

Good luck,

Don't most of the GM altenators have a place for a hex wrench in the end of the shaft? I know my 89 Riv has it, I think it is abouta 3/8 in you need to slip a piece of pipe over the hex wrench to be able to hold it unless you have a hex socket. Hope your lucky and have the hex provision,it makes it much easier.

Glenn

 

[Achilles]

The belt tensioner on my 86 has a slot for the 1/2" breaker bar that works fine.