Classic/Antique Car Repair: harmonic blancer, woodruff key, crankshaft

Question
rebuilt a buick 401.. balancer was cracked replaced with one from junk eng. now have a vibration.the old balancer is gone.how can i solve problem without balancing engine.1964 wildcat.how many different weight balancers did they make for that engine.

Answer
There is only one balancer for the 401 engine, as far as I know.  Are you sure it is the balancer that is causing the problem?  Did the engine run smooth before you changed the balancer?  If so, are you certain that the balancer is on correctly, with the woodruff key in place and not sheared off?  

If it is, then either the unbalance is from some other problem (like the torque convertor not being properly indexed to the crankshaft, or being out of balance itself) or esle the replacement balancer has slipped on its center pulley, and is a bad unit.  I'd try another balancer if you can find one.  

Also, of course, you must be certain that the engine is not misfiring, and has even compression on all 8 cylinders.

Dick.