First, I do not belive the B-series motors use rockers (like d-series). The camshaft sits directly on the valvetrain...
Man, you could be in for a rude awakening...
Do u have an ITR motor (B18C5)?
Did you re-assemble the motor yourself?
I know for a fact, that you must use a special strain gauge on the connecting rod bolts to properly torque them...
I hope you did this..
If not, then that's prob your problem...
If you did assemble the motor CORRECTLY, then it could be a couple of things... However I stress correctly, because there are tolerances that should be checked when re-assembling...
Check in this order
-timing belt cover
-rod bolts
-clearances

Oh and why did you have to replace the crankshaft? Was it destroyed before, cause that could have caused other major problems if it was destroyed...

Hope this helps,
Keep us posted...