vibration issue

[73stallion]

after installing this 5.0, it has a BAD vibration off idle. we pulled the trans back out, turned out it had a 28oz flywheel in it. we installed a new 50oz flywheel, put it all back together, vibration is still there. harmonic balancer is correct. what else could it be? could the vibration from the 28oz flywheel over time tear something up on the crank????

 

[Rustytruck]

Does the vibration change any when you push the clutch in? if so I would check the balence with the flywheel, pressure plate and clutch disk if necessary. If running an automatic the converter may be out of balence. The harmonic balencer may have slipped its ring and is out of balence.
all a pain in the butt to deal with. Have you made sure all cylinders are firing?

 

[Bronco Junkie]

Is it a new harmonic balancer? I bought a new one and my machinist had to re-balance it.

 

[73stallion]

Clutch in makes no difference. Not a new balancer.

 

[green77bronco]

did you check to make sure the Dowel pins are in the flywheel, and yes I learned that the hard way.

 

[73stallion]

no dowel pins in the flywheel, this one isn't made for the. bolts are a snug fit in the holes.

 

[jw0747]

all motor and tranny mounts in good shape?

 

[73stallion]

all engine and trans mounts brand new. gonna pull the belt off tomorrow and see if there's an accessory causing it (highly doubt it). need to replace the belt anyway. but it feels like it's internal, it's a heavy vibration. this bronco has been here a few months and i'm SO ready for it to go away...................