Mercury - Quicksilver Crankshaft Pulley For V6 & V8 MerCruiser Engines (305, 350, 377 CID) 807730T. Overview. A good crankshaft pulley does more than spin a belt - it keeps your entire accessory drive system running smooth and in sync. The Mercury 807730T Quicksilver Crankshaft Pulley is built for V6 and V8 MerCruiser engines (305, 350, 377 CID) from 1998 and newer that use a serpentine belt setup. It's precision-machined to transfer power cleanly from the crankshaft to your alternator, steering