What is the difference between a Chevy 168 tooth flywheel an a 153 toothed flywheel?

Answer 1

Just as the name implies the 168 tooth flywheel has 168 tooth ring gear and the 153 tooth flywheel has 153 teeth on it's ring gear. In the "old days" of high performance the manual 4 speed transmissions allowed a larger diameter 11" clutch to be used with the higher performance engines with the larger 168 tooth wheel. In addition to this the larger diamater flywheel gives the starter better mechanical advantage to turn over high compression engines because of the greater number of teeth on the larger ring gears. Chevy uses a number of different starter noses on their starters. This is the aluminum piece that the bendix gear is in at the "business end" of the starter. This nose is the piece that mounts the starter to the block. This nose is the part of the starter that moves the starter motor in closer to the flywheel on the 153 tooth and farther out away from the flywheel on the 168 tooth wheels. I believe the starter motors are mostly the same except for the HD starters which have a longer stator and rotor for the high compression engines of "the old days". These longer starters allowed the starter motors to develop more torque to turn the higher compression engines over to start them.