Is the pulley on the crank a balanced part? Will it go on more than one way? I noticed after I took it off (to do my opti) that my motor seems to have a little vibration. I may have had this all along and not noticed but working on it you really start looking and listening hard for such things.

 

yes it is weighted but there is only one way to put it on, the spokes are not evenly spaced

 

LT engines have a damper, not a balancer. The crank hubs on stock LTs are not keyed, so the three-spoke hub can slip, but that isn't a problem.

Most LT rebuilds use an aftermarket SFI hub and damper with a key. Then you can maintain the mechanical timing reference.

WD

 

Maybe the vibration is an ignition miss. If you did not remove the crank hub, a vibration from the pulley is in your head (since it can only be put back like it was).

 

The engine seems to run really well and I dont feel a miss just a weird sort of vibration at about 2500 RPMs it feels like a strumming its hard to describe I did check and the pulley seems to have uneven spokes so I should not have been able to put the bolts in and tighten it down if it was off correct? What I did find was a piece of it missing on the backside where I must have ummmmmm tapped it with a hammer trying to remive it. I think I will need to get a new one I may just go with underdrive if I do. It wont hurt the belt but every bit of balance on my crank at 5500 RPMS is probably helpful.

 

You might have damaged it by beating on it.

 

Yes I must have cracked it and a piece came out after I ran it. I took a good look at it last night after I wrote this and found it. I am thinking a new dampener and underdrive pulleys would give me a bit more power also right? I know you dont gain what they claim but even 5 HP if you have to buy a new one anyway is a plus. Are there any down sides of underdrive pulleys?

 

Jeg's makes an LT1 type SFI approved underdrive damper and hub w/ key slot (their brand). And the cost is very reasonable.

And, the underdrive will "free-up" a few extra HP.

WD

 

Thanks I will check that out

 

Underdrive pulleys can sometimes cause charging problems.

 

That is true, if you drive your LT performance car "just like" your grandmother drives her 83 Buick Skylark to Church and back on Sundays.

However, if you've got your foot in it all the time hot rodding around town (like any decent LT car should be driven) you'll probably make-up-for the 10 percent under-drive!

WD

 

He asked for any down side, so I posted what some have experienced. I'm sure they all did not drive like a grandma.

 

I had charging problems with the ASP U/D pulley set. I wouldn't recommend an U/D pulley. There's little to be gained. I don't drive like a grandmother.

 

On a more serious note, first hope I didn't offend any grandmothers on the forum, or people who drive their LTX cars well under posted speed limits.

I'm running an under-drive damper and was initially concerned about the charging. So, I measured the charge voltage with a DMM. It was 13.5 volts at an idle, which is at the low end of the desired float voltage. But still completely acceptable. Then as the RPM increases I would expect the voltage to increase until the regulation threshold limits it probably to about 14.5 volts.

Therefore, if you’re going to run an under-drive pulley system it would probably be a good idea to measure the float voltage at an idle as I did.

However, if your desire is to have a really big stereo system and ride around town and make a lot of noise, you should not run an under-drive system.

WD

 

Instead of dealing with it, why not get a smaller alt pulley to match?

On a side note how much of a concern is having a SFI dampner on a newer build like mine in my sig? I mean how much better does it dampen? Or is this only for track regulations?