[Railcarmover]

All that being said,the B mechanical advance distributor is a marked improvement over the A distributor,automatic spark advance provides smooth acceleration and eliminates spark knock,a leading cause of main bearing failure..on model a engine. The B had improvements to the crankshaft journal diameter and pressure lubrication to the main bearings,along with the mechanical advance distributor,all helping to end the main bearing issue with the A..later B engines also had counterbalanced crankshafts.