Mercury - Distributor Cap Prestolite Ignition System Marine-Grade Polymer 9766Q1. Overview. There's a certain comfort that comes from turning the key on a V8 MerCruiser and hearing it fire up clean and strong. No coughing, no hesitation-just that familiar rumble that tells you your boat's ready for another long run. The Quicksilver 9766Q1 Distributor Cap helps keep that confidence alive. It's one of those quiet, behind-the-scenes parts that holds everything together, routing spark where it needs