1966 Evinrude 6 HP Fisherman Outboard Specs & Part Numbers
Technical Guide: 1966 Evinrude 6 HP Fisherman Outboard Motor
The 1966 Evinrude 6 HP Fisherman is a legendary two-stroke outboard motor revered by vintage marine enthusiasts and anglers alike. Known for its rugged reliability, smooth trolling capabilities, and lightweight portability, this twin-cylinder motor is a classic representation of Outboard Marine Corporation’s (OMC) golden era of engineering. This technical guide provides comprehensive specifications, maintenance data, and historical context for restoring or maintaining this classic powerplant.
1. Overview & Technical Specifications
The 1966 Evinrude Fisherman (Model numbers 6602 for the short shaft and 6603 for the long shaft) is a twin-cylinder, loop-charged two-stroke engine. It was designed to offer a perfect balance of power and portability for small fishing boats, rowboats, and dinghies.
| Specification | Detail / Value |
|---|---|
| Manufacturer | Evinrude (Outboard Marine Corporation – OMC) |
| Year of Production | 1966 |
| Model Numbers | 6602 (15″ Short Shaft), 6603 (20″ Long Shaft) |
| Horsepower | 6.0 HP @ 4,500 RPM |
| Cylinders | 2 (In-line) |
| Displacement | 8.84 cubic inches (145 cc) |
| Bore x Stroke | 1.9375 inches x 1.500 inches (49.2 mm x 38.1 mm) |
| Fuel-to-Oil Ratio | 50:1 (Using TC-W3 certified 2-stroke outboard oil and 87 octane unleaded gasoline) |
| Fuel System | Single carburetor with fuel pump (Single-line fuel system) |
| Starting System | Manual pull-start (recoil) |
| Weight | Approx. 51 lbs (23 kg) |
2. Common Maintenance & Tune-up Specifications
Maintaining a 1966 Evinrude 6 HP requires periodic attention to the ignition system, fuel delivery, and cooling. Below are the critical tune-up tolerances and replacement part specifications.
Ignition System (OMC Universal Magneto)
The ignition system is located under the flywheel. It utilizes a mechanical breaker point setup with dual coils and condensers.
- Spark Plug Type: Champion J6C (or RJ6C for resistor type)
- Spark Plug Gap: 0.030 inches (0.76 mm)
- Breaker Point Gap: 0.020 inches (0.51 mm) at high point of the cam
- Condenser Capacity: 0.18 to 0.22 microfarads (mfd)
- Ignition Coil Note: The original black plastic-coated coils are notorious for cracking over time, causing spark loss when the engine warms up. It is highly recommended to replace cracked coils with modern green epoxy-coated OMC/Sierra replacement coils.
Carburetor & Fuel System
- High-Speed Orifice (Jet): Fixed jet (Size #29, varies slightly by elevation).
- Low-Speed (Idle) Mixture Adjustment: Adjustable needle valve. To set: Gently seat the needle valve clockwise until bottomed out, then back it out 1.5 turns as a starting point. Adjust in 1/8-turn increments with the engine running warm in gear to find the smoothest idle.
- Fuel Pump: Pneumatic pulse-driven fuel pump (mounts to the side of the cylinder block). Rebuild kits are widely available (OMC Part #397839).
Cooling System & Lower Unit
- Water Pump Impeller: Located inside the upper gearcase housing on the driveshaft. It is a rubber vane impeller that should be replaced every 2–3 seasons or if water flow from the bypass outlet (exhaust housing relief port) becomes weak.
- Gearcase Lubricant: Use standard marine 80W-90 gear lube (or OMC Premium Blend/Type C).
- Capacity: Approx. 9 fl. oz.
- How to Fill: Always fill from the bottom “Drain” screw hole until fluid begins to seep out of the top “Keep Level” screw hole. Replace both washers to prevent water intrusion.
3. Notable Features & History
The mid-1960s marked a transition point for portable outboard motors. The 1966 Evinrude 6 HP Fisherman benefited from several design advancements that made it incredibly user-friendly compared to its 1950s predecessors.
The Shift to 50:1 Fuel Mixture
Prior to 1964, most OMC outboards utilized a heavy 24:1 gas-to-oil ratio. Thanks to advancements in metallurgy, needle bearing design on the crankshaft and connecting rods, and improved 2-stroke oils, Evinrude rated the 1966 model for a 50:1 ratio. This significantly reduced exhaust smoke, minimized spark plug fouling, and lowered operating costs.
Single-Line Fuel System
In the 1950s, OMC outboards relied on pressurized dual-line fuel tanks. By 1966, the 6 HP Fisherman featured a modern vacuum-pulse fuel pump, allowing the use of standard, safe, single-line external fuel tanks. This makes running these motors today much easier, as they are compatible with modern universal marine fuel tanks and lines.
Full Gear Shift (F-N-R)
Unlike smaller utility outboards of the era that required turning the motor 180 degrees to reverse, the 6 HP Fisherman featured a full mechanical gear shift lever on the starboard side of the lower cowling. This offered True Neutral, Forward, and Reverse gears, making docking and maneuvering in tight spaces exceptionally easy.
The “CD” Series Legacy
The powerhead and midsection design of the 1966 model belong to a family of engines (often referred to as the “CD” series by enthusiasts) that remained in production with minor cosmetic and mechanical variations from 1965 until 1979. Consequently, replacement parts—including gaskets, impellers, carb kits, and ignition components—remain inexpensive and widely available today, making this one of the easiest vintage outboards to keep running.