Mercury - Quicksilver Blue Wire Spark Plug Wire Kit V8 Inboard Ignition System Marine Grade 847701Q24. Overview. The Quicksilver 847701Q24 Blue Wire Spark Plug Wire Kit is built for V8 MerCruiser 350 Magnum and Horizon inboard engines from 1999-2007. Each wire is the exact length your engine needs, with durable boots already installed for a clean, easy fit. Made by Mercury Marine, this OEM set keeps your ignition strong and reliable, giving you smoother starts, steady idle, and solid power when