Damn, Boosty, this is quite the update since I last saw the thread Best of luck to you. I hope it'* as "simple" as a flywheel!!!

Ah man, that sucks...

Bottom end is no fun, so I hope it'* the flywheel, but wouldn't Intense have noticed it?

You need to look at the flexplate very closely... I think when we put mine on, Thomas was having some problems with some of the bolts going in a bit funky. It seemed like one of the holes wasn't lining up correctly, so we did some monkeying around and finally it went on properly. It has to be something with the external balance... I don't know HOW you could "bend" a crankshaft. You could probably play baseball with a crank and ding it up, but not bend it. It just seems ludicrous to me.

Look over EVERYTHING.... balance shaft, cam timing, flexplate, HB. Leave no stone unturned! You'll figure it out.

Are you sure you are firing all six cylinders :?:
A similar vibration can occur if you are only running on a few cylinders.

When I first started the Firebird after it sitting all this past winter, it ran the same way for the first couple of minutes, then smoothed out as it warmed up.

So I pull out the spark plugs to clean and re gap them only to discover, when checking my records for the gap setting, that they were last replaced in 1993.

I'm sure with all your Gearheadedness that you've ruled out all the possibilities.

If it is a balance issue because you didn't rebalance the rotating assembly after changing a piston, then my condolences.

What happened when you revved the engine, Bill? Did it still shake, or did it smooth out at all?

I want to ensure wel all are super clear on the video being a poor representation of the amount of movement. The out of balance is probably about 3x what the video picked up. Seriously.. I would have gone into superduper memory hogger video if I realized it was not represented reasonably.

Ben... you keep mentioning the balancer marks and I agree, that'* the first suspect and exactly what it'* acting like...can you see any reason from those marks that it could possibly or even remotely be off? I wish I could..can't though. (BTW..please answer this one..)

Dan'* first few questions were "is it leaking badly?", "Did you set the balancer marks up correctly?" Once he saw the pics and knew they were my engine..he got very quiet. He'* seen tons of problems and can't seem to provide a suggestion, especially since he knows like we do..the flywheel can only go on one way.

Paul.. Yes, I've removed wire by wire and noticed that cylinder go dead as they were unhooked. All appear to be 100%

What we know on this one..
The balancer is properly aligned in the pictures and nothing changed from the pics to final bolting.
The flywheel bolts started..and I had a gut feeling but ruled it out because it can only go on one way.
If the crank were bent or messed up.. the seals would have to leak.
When the rpm is brought up slightly..things tend to smooth a bit showing it'* balance.

I'm honestly thinking flywheel, if that'* the case I get a prize for achieiving something engineered to be impossible.

i dont know if anyone said this...


But you replaced one Piston right?

What if that one piston is like 2oz heavier or lighter then the others? :?

the piston replaced was #1, the vibration is in the rear of the car...Bill and i discussed, and it wouldnt make sense

An S2 L67 piston is an S2 L67 piston. It'* the same all the way. And I have no question that Ed Morad knows an L67 piston. (It'* been thought of already thought...keep the good stuff coming).

Dan wanted to bet me $50 it'* not the flywheel...I think I'm gonna take that.