Mercury - Quicksilver 816608Q81 Red Wire Spark Plug Wire Kit MerCruiser Inboard Tow Sports Engines Delco HEI Ignition 816608Q81. Overview. Your ignition system works hard every time you hit the key, and it needs solid, reliable plug wires to keep your engine performing like it should. The Quicksilver 816608Q81 Red Wire Spark Plug Wire Kit is built for MerCruiser inboard tow-sports engines (1999-2001) with Delco HEI ignition systems, delivering strong, consistent spark and long-term reliability i