This Factory Service/Repair/Workshop Manual provides comprehensive information for the Mercury Mercruiser 496CID/8.1L gasoline engine. This powerful engine, featuring Electronic Fuel Injection and available in various configurations including the 496 Mag HO, 496 Mag, 8.1S HO, and 8.1S Horizon, is designed for demanding marine applications. The manual covers essential components such as the ignition system, fuel delivery system, cooling system, and exhaust components, ensuring optimal performance and longevity for your vessel. The purpose of this manual is to serve as an authoritative resource for owners, mechanics, and technicians. It details critical maintenance procedures, troubleshooting guides, and technical specifications necessary for the upkeep and repair of the 496CID/8.1L engine and its associated systems, including Velvet Drive 5000 Series and Hurth transmissions. By following the instructions and guidelines within this document, users can effectively maintain their Mercury Mercruiser engine, ensuring reliability and safety on the water.