8lb. fly wheel?

will i spin the bearings in my block and fuk up the motor by throwin a 8LB. flywheel on it w/ no work done to the bottom end at all?

see other thread.

ive never heard of that happening and 8lbs will make it fun to drive. the only time ive heard of spinning all hte main bearings was when someone used those stupid underdrive crank pulleys