1947 Evinrude 5.4 HP Zephyr Outboard Specs & Part Numbers
1947 Evinrude 5.4 HP Zephyr: Technical Guide
The 1947 Evinrude Zephyr is one of the most unique and fascinating outboard motors of the immediate post-World War II era. While most portable outboards of this horsepower class were rough-running single or twin-cylinder engines, Evinrude engineered the Zephyr as a remarkably smooth four-cylinder powerhead. This guide provides comprehensive technical specifications, maintenance procedures, and historical context for owners, restorers, and vintage outboard enthusiasts.
Overview & Specifications
The 1947 Evinrude Zephyr (primarily Model 4404) is a lightweight, rubber-mounted outboard motor. Despite its four-cylinder design, it weighs only around 46 pounds, making it highly portable for its time while offering unparalleled smoothness due to its overlapping power impulses.
| Specification | Value / Measurement |
|---|---|
| Manufacturer | Evinrude Motors (Milwaukee, Wisconsin) |
| Model Number(s) | 4404 (Standard Shaft) / 4414 (Long Shaft) |
| Horsepower Rating | 5.4 HP @ 4,000 RPM (OBC Certified) |
| Engine Configuration | Four-cylinder, two-stroke, alternate firing |
| Displacement | 9.7 cubic inches (159 cc) |
| Bore x Stroke | 1.50 in. x 1.375 in. (38.1 mm x 34.9 mm) |
| Fuel Tank Capacity | Approx. 1 Gallon (Integral) |
| Recommended Fuel-to-Oil Ratio | 16:1 (1/2 pint of oil per 1 gallon of gasoline) |
| Oil Type | TC-W3 Two-Stroke Outboard Oil (or vintage SAE 30 non-detergent outboard oil) |
| Dry Weight | 46 lbs (20.8 kg) |
Common Maintenance & Tune-up Specs
Working on a vintage four-cylinder outboard requires precision. Because the cylinders are small and clearances are tight, keeping the ignition and fuel systems perfectly tuned is essential for reliable starting and smooth idling.
Ignition System Specs
- Spark Plug Type: Champion J8C (modern replacement for the original Champion J8)
- Spark Plug Gap: 0.025 inches (0.64 mm)
- Ignition System Type: Flywheel Magneto (typically Bendix-Scintilla or Evinrude proprietary dual-coil system)
- Breaker Point Gap: 0.020 inches (0.51 mm)
- Note: The Zephyr uses two sets of points and two double-ended coils to fire all four spark plugs. Ensuring both sets of points are timed identically is critical to even power distribution across all cylinders.
Carburetor & Fuel System
- Carburetor Model: Tillotson or Evinrude float-feed type with adjustable low-speed and high-speed needle valves.
- Initial Needle Settings:
- High-Speed Needle (Bottom): Open 3/4 to 1 turn from gently seated.
- Low-Speed Needle (Top): Open 1 to 1-1/4 turns from gently seated.
- Fuel Type: Regular unleaded gasoline (87 octane). Avoid ethanol blends, as modern ethanol will quickly degrade vintage cork fuel floats, gaskets, and fuel lines.
Cooling & Lower Unit
- Cooling System: Water-cooled via a positive displacement rotor pump.
- The pump relies on a synthetic rubber impeller/rotor located in the gearcase. If the motor has sat idle for years, this rotor must be replaced before running to prevent catastrophic overheating of the aluminum powerhead.
- Gearcase Lubricant: Original spec was “Evinrude Gear Lubricant Type A” (a semi-fluid grease).
- Modern equivalent: Lubriplate 105 (an anhydrous calcium-type grease) or a specialized vintage outboard gear grease. Do not use modern high-viscosity 90W gear oil unless the gearcase seals have been updated to modern lip seals, as it will quickly leak out of the original bushing joints.
Notable Features & History
The Famous “Baby Four”
The Evinrude Zephyr is affectionately known among collectors as the “Baby Four.” Prior to World War II, Evinrude was famous for its massive four-cylinder “Elto” and “Speeditwin” racing engines. In 1940, Evinrude applied this multi-cylinder technology to the light-utility class, introducing the 5.4 HP Zephyr. Production was halted during WWII to accommodate military manufacturing and resumed in late 1945, continuing through the late 1940s with minimal design changes.
Engineering Highlights
- True Multi-Cylinder Smoothness: While a 5 HP engine of the era was typically a vibra-prone single cylinder, the Zephyr delivers four power impulses per revolution. This design minimizes vibration, allowing for incredibly quiet operation and smooth trolling speeds that won’t fatigue the operator or shake the boat.
- Simplex Recoil Starter: Positioned on top of the flywheel, the Simplex starter was a massive upgrade over the simple wrap-and-pull starter ropes common on cheaper motors of the 1940s.
- Co-Pilot Steering: Features a friction-brake steering mechanism that holds the motor in position when the operator lets go of the tiller handle.
- Aluminum Alloy Construction: Extensive use of lightweight Alcoa aluminum alloys for the powerhead, exhaust housing, and brackets kept the weight of this complex machine equivalent to standard two-cylinder outboards.
Restoration & Collectibility
Today, the 1947 Zephyr is a highly prized collector’s item. Because of its four spark plugs, dual coils, and intricate intake manifold path, it is more complex to rebuild than a standard twin. However, when properly restored, a Zephyr starts easily, idles down to an incredibly quiet whisper, and exhibits a unique exhaust note that is distinct from any other classic outboard on the water.