One thing to look out for when installing new bearings, is that the shells have the correct "nip", that is, they are slightly bigger than the hole they go into. Some people think the bearings are located with the little tangs, but they are really located with the nip, so make sure this is correct during assembly. Another little thing is clean the bearing areas before installation, if there is a speck of paint or dust under the shell, it can cause the bearing to "lock up" when the bolts are tightened. Crankshafts should be able to be turned by hand after assembly of new bearings, if its tight, something is wrong.