Mercury - Distributor Cap and Rotor Kit Marinized V6 Engines by GM Delco HEI Ignition 850484T3. Overview. Every boater knows that smooth starts and steady power depend on one thing - reliable ignition. The Mercury Quicksilver 850484T3 Distributor Cap and Rotor Kit is the quiet hero behind that confidence. It's the part that keeps your MerCruiser V6 engine firing clean and consistent, trip after trip, no matter the weather or water conditions.. If you've ever heard that satisfying growl of a tune