1964-1998 OMC Cobra, King Cobra & Stringer 2.5L - 7.5L / 120hp - 454hp Sterndrive Service Manual

• Covers 1964–1998 OMC Cobra, King Cobra, and Stringer sterndrive units paired with 2.5L to 7.5L (120 HP–454 HP) inboard engines across in-line and V-block configurations
• Official OEM publication containing 1183 pages of raw technical reference material
• Features 47 exploded-view assembly diagrams and 32 electrical wiring schematics
• Documents the structural and mechanical transition from early Stringer units to the 1978-onwards Cobra sterndrive systems

Sterndrive and Engine Technical Coverage

This manual delivers comprehensive reference material for assembling and maintaining OMC sterndrive and inboard propulsion systems. It breaks down the mechanical layout of GM and Ford V8 engines, GMC in-line engines, and V6 configurations, including the 225, 229, and 4.3L variants. You get specific removal and installation procedures. Valve lash adjustment charts and camshaft service guidelines are explicitly detailed.

Marine propulsion systems operate under extreme stress, making correct assembly critical. Always ensure strict safety protocols are followed in the workshop, and rely on qualified marine technicians for complex structural interventions or high-voltage electrical procedures.

Beyond the engine block, chapters define the mechanical requirements for tilt mechanisms, steering linkages, and fuel delivery networks. The text covers carburetor bench adjustments for Rochester and Holley units. It also tackles battery and alternator charging system troubleshooting. Critical marine maintenance is heavily featured, focusing on below-waterline service, anode (zinc) installation, and precise corrosion protection protocols for saltwater environments.

Specification and Data Highlights

Accurate data is the backbone of any successful marine rebuild. Engine compression values for the 1964–1998 OMC Cobra range are documented at 150–170 PSI, while 120 PSI serves as the standard baseline for mechanically sound modern variants. The engine service data includes multi-stage sequences for cylinder head bolt torque values. Intake valve clearances sit at a precise 0.003–0.005 inches on specified models.

Cooling system maintenance intervals and exhaust manifold mounting protocols are provided for the entire 120–454 HP lineup. A dedicated compression testing chart offers a quick reference to identify performance thresholds at various PSI readings, streamlining the diagnostic process on the shop floor. The expansive technical data thoroughly documents the drivetrain, cooling, and electrical specifications needed to keep these marine powerplants operational.