1964–1986 OMC 4/6-cylinder, GMC V6, GMC V8, and Ford V8 Sterndrive Service Manual (P/N 1051858)

This official 574-page OMC OEM publication (P/N 1051858) delivers comprehensive service data for the 1964–1986 OMC Sterndrive production run. It documents engine, chassis, electrical, and carburetion specifications for the complete range of in-line and V-series powerplants.

• Covers GMC in-line 4 and 6-cylinder, GMC V6, GMC V8, and Ford V8 inboard engine configurations.
• Features 143 exploded-view diagrams for precise component identification.
• Includes 18 wiring schematics targeting electrical routing and tilt system diagnostics.
• Outlines intermediate housing teardowns, Tru-Course steering adjustments, SelecTrim calibration, ball gear replacement, and shift box synchronization.
• Details Carter RBS and Rochester 4MV carburetors, Delco-Remy distributors, Autolite starters, and lower unit rebuilding.

Engine Service and Diagnostic Details

The manual breaks down internal component specifications across all main engine groups. You get exact documentation on valve timing principles, camshaft installation sequences, and cylinder head reconditioning. Maintenance sections outline critical parameters for oil and water pump teardowns. Tilt mechanism diagnostics are heavily featured. Crucially, the text differentiates between early 1964–1977 units and later post-1978 models. It details carburetor bench adjustments for Rochester and Holley configurations, alongside exhaust manifold and cooling system data. Instead of relying on expensive marine shops, DIYers and mechanics get step-by-step troubleshooting procedures to fix complex issues like synchronizing the shift converter, servicing the Prestolite and Mallory ignition systems, or rebuilding the power assist servo. The PDF is supplemented by spark advance charts, tune-up specification tables, gear ratio charts, functional diagrams, and cutaway views. Marine powertrain maintenance inherently involves significant mechanical risks, particularly when handling heavy engine blocks or pressurized fuel lines. Always apply standard shop safety practices. Consider consulting a certified technician before attempting complex diagnostic work on these systems.

Technical Specifications and Clearances

Critical reference values for engine assembly and tuning are fully documented. For example, crankshaft bearing clearance is listed exactly at 0.0005" to 0.0025". Cylinder head flatness tolerances dictate a maximum deviation of 0.003" per six-inch section. Intake valve guide wear limits are firmly set at 0.001". The resource also provides full ignition timing adjustments and centrifugal advance tables for all covered models, ensuring you have the exact factory data required for accurate tuning. Understanding these complex system requirements is essential for accurate workshop procedures. When performing a repair on these specific stern drives, technicians must be aware of certain mechanical traps. For instance, running the engine without water circulating through the lower unit for even five seconds will instantly destroy the water pump impeller. Furthermore, when shimming the pinion bearing, you must physically rotate the housing to break the oil film before measuring; an unbroken film will result in a false reading and subsequent gear failure. Having these exact factory tolerances directly at your workbench prevents structural distortion and accelerates daily service bay workflow.