92 LT1 Harmonic Damper Alignment ?
 

How critical is the exact alignment of a harmonic balancer on a 92 LT1? I get a vibration over 3200 rpm and I'm suspecting the damper may have moved on the crank due to a hub bolt that may not have been properly torqued.

Any comments or experiences would be appreciated!!

Brian

The LTx dampers are "0" balanced.The engine is balanced via the flywheel.I doubt it has slipped those hubs are a real pain to move.There is no mark to align the hub with other than going to TDC on #1 and the arrow should be at 12:00.

they should be balanced, but many aren't. i had read on this forum where someone claimed many engines were fine-tuned for balance at the factory by pressing weights into the holes on the damper. i didn't realize how much difference there could be until i dropped my 396 into the car.

the 396 was completely balanced without the damper, since i had assumed it was 0 or close to it. the engine vibrated quite a bit. i assumed the clutch pp was slightly off center (since LTx engines don't have dowel pins to locate the pp), or out of balance. i basically lived with it since i didn't have time for a clutch swap, and it was closer to annoying than destructive.

a year later i installed an ASP underdrive damper. this comes already balanced from ASP. i didn't expect any difference in balance, i got the ASP to try and slow down the ps pump. (i auto-x.) the instant i fired the engine after the install i realized the vibration was completely gone.

so, i'd make an effort to make sure the hub goes back on as close as possible to how it came off. that said, it sounds like you never removed yours, so what i said doesn't really apply. like redeasy, i sort of doubt the hub slipped on the crank. (not supercharged, right?)

-michael

Many people run into that same situation on LT-1's, (especially on used crate motors that have no balancer, or it was removed without being marked).....there's little choice but to reinstall the balancer in a different location, say 45 degrees from where it is now, drive it, if the vibration is gone, you got it, if not move it another 45 degrees, so on and so fourth.....It's tedious, but since there's no keyway (as in a good design) not much else to do.........the "supposed" zero balancer on my 95 LT1 has so much weight removed on it (on one side) from the factory, that if it slipped on the crank or I intalled it wrong, It would vibrate for sure..........

The car is not supercharged.

I have removed the damper to replace the OPTI but I had the vibration before the new OPTI was installed.

I also understand that the damper only goes on one way because of the way the 3 damper holes align. When I reinstalled the damper I used the factory marks. However, I noticed what looked like an old paint mark on the damper and didn't know if that had any significance.


Would an after market damper cure the problem if it is damper related?

And finally when I got the car 6 years ago I didn't remember any vibration and my son said the same thing.





Thanks for the replies!!

Brian