[trularin]

Sounds like you are off balance. You may have to go back and make sure you have:

a) all of the bolts and of the same length and weight ( sounds excessive, but I've done it )
b) The balance lines match. If you had someone balance the engine with the flywheel, they may have put two lines to match when installing the flywheel.
c) See if the bearing you put in is NOT out-of-round.

Those should cover most of a babance problem based on what you have described.

Just my $0.02