The procedure for internal balancing begins by measuring the weights of the piston, wrist pin, rings, rod and rod bolts. (Assuming the flywheel and damper are neutrally balanced) The weights are computed and locations on the crank are determined where weight must be added or removed to make the rotating assembly neutrally balanced. External balancing requires weight to be affixed to the damper and flywheel and the whole assembly is then balanced. The damper and or flywheel cannot be changed unless the whole assembly is rebalanced. All of our engines are internally balanced.