I'm giving my first engine build a shot but I'm confused about balancing the rotating assembly. Is this step necessary? If so Do i take my rotating assembly to a machine shop for balancing or do I bring them the short block already assembled?

Also I've heard different arguments, are you supposed to balance the rotating assembly with the flywheel/pp on or off?

 

my shop needs: rods, pistons, wrist pins, crank, flywheel with bolts, pressure plate, harmonic balancer and all bolts... may vary shop to shop...

but - it can not be assembled.

 

Everything gets balanced individually. But if these are new aftermarket parts they should come balanced already. The only thing I have balanced by the machine shop is the crank.