This is the paper on my little 283 for my 40 Ford coupe. This is the inital spin. This is with the 4 Bobweights, flywheel, pressure plate, harmonic balancer, lower front pulley and lower timing chain gear installed on the crankshaft. This is everything that rotates.
Now the sheet after the crankshaft, flywheel and harmonic balancer are balanced.
Notice that the out of balance at 1000 RPMS on the inital spin is 5.44 lbs. Then compare it to the 5000 RPMS out of balance after balancing the crank, flywheel and harmonic balancer (4.87 lbs.)
It is less at 5000 RPMS than before at 1000 RPMS. The Bobweight did not change. All the pistons, rods, rod bearings and rings were already made the same weight (Bobweight).
What did change was the crankshaft throws (drilled) and the flywheel drilled and the pressure plate rotated 120 degrees to a more in balance location.
To try to make this simple....... when you speed balance a tire and rim on your car.....you balance it to the hub and rotor also to get the best balance.
When you just spin the rim and tire on a tire machine...... it can be balanced but MAY not ride smoothly because it is out of balance after it was bolted to the hub and rotor.
I know of nobody who records the weight of a flywheel or flexplate after balancing.
A 383 is externally balanced. This means that the rotating assembly is balanced by the harmonic balancer and flywheel. Just try a 350 flywheel. HA HA HA