🏷️ Basic Information Identification Make: Chris Craft Model: Hercules Generation: Vintage (1940s-1960s) 📋 Manual Details Document Information Manual Type: Service, Repair, and Adjustment Manual Language: English Format: PDF Download ⚙️ Engine Specifications Engine Configuration Engine Type: Inline 4-Cylinder and Inline 6-Cylinder Engine Family Engine Series: K, A/B, M, W, WB Performance Displacement: Varies by specific engine model (e.g., K-Series ~250 cu in, M-Series ~320 cu in) Power Output: Varies by specific engine model and tuning (typically 60-100+ HP) Fuel System Carburetion: Single or dual downdraft carburetors (e.g., Zenith, Marvel-Schebler) Ignition System Ignition Type: Battery and Coil Ignition (Distributor) Cooling System Cooling Method: Water Cooled (Direct Drive Raw Water Cooling) Lubrication System Oil Type Recommendation: SAE 30 or SAE 20W-50 (specific viscosity may vary based on ambient temperature and engine wear) Engine Construction Block Material: Cast Iron Cylinder Head Material: Cast Iron 🔧 Transmission Gearbox Type: Marine Reduction Gear (often Borg-Warner or similar) Gear Ratios Reduction Ratios: Common ratios include 1.5:1, 2:1, 2.5:1 (variable based on application) 🔧 Maintenance Routine Service Oil Change Interval: Every 50-100 operating hours or annually Fluid Capacity Oil Capacity: Approximately 5-7 quarts (depending on engine model and oil filter) Tune Up Procedures Spark Plug Gap: Typically 0.025-0.030 inches (check specific engine data) Ignition Timing: Specific timing varies, often around 5-10 degrees Before Top Dead Center (BTDC) at idle (check manual) Valve Adjustment Valve Lash Intake Hot: Typically 0.016 inches (check specific engine data) Valve Lash Exhaust Hot: Typically 0.020 inches (check specific engine data)