Mercury - Quicksilver 816336Q NGK BPR6EFS Standard Spark Plug Sold Individually Marine Engine OEM Plug 816336Q. Overview. A fresh set of plugs can make your engine feel brand new. The Quicksilver 816336Q NGK BPR6EFS Standard Spark Plug delivers consistent ignition, better combustion, and long-lasting performance for your Mercury Marine engine. Pre-gapped to factory specifications, it's ready to drop in and get your motor firing crisp and clean.. Whether you're running a quiet cruise or throttlin