Mercury - Distributor Cap Marinized V6 Engines by GM Delco HEI Ignition 850484T2. Overview. If you've spent any time maintaining your own boat, you know that dependable ignition means everything. The Mercury Quicksilver 850484T2 Distributor Cap is one of those small but vital components that separates a smooth-running engine from a frustrating day at the dock. Built for marinized V6 MerCruiser engines by General Motors, this cap keeps your ignition system firing clean and consistent so your powe