1958 Evinrude 10 HP Sportwin Outboard Specs & Part Numbers
1958 Evinrude 10 HP Sportwin: Technical Guide
The 1958 Evinrude Sportwin 10 HP (Model 10016 for standard 15-inch shafts and Model 10017 for 20-inch long shafts) is a legendary outboard motor representing the pinnacle of late-1950s marine engineering. Renowned for its smooth operation, quiet performance, and robust build quality, this motor remains a favorite among vintage outboard collectors and classic boat enthusiasts today.
This technical guide provides comprehensive specifications, maintenance parameters, tune-up procedures, and historical context for restoring or maintaining this classic machine.
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1. Overview & Technical Specifications
The 1958 Sportwin is an alternate-firing, two-cylinder, two-stroke outboard engine. It features a full gearshift (Forward-Neutral-Reverse) and was designed during an era when Evinrude focused heavily on noise reduction and vibration isolation.
| Specification | Value / Measurement |
|---|---|
| Horsepower | 10 HP @ 4500 RPM |
| Cylinders | 2 (In-line, alternate firing) |
| Displacement | 15.0 cubic inches (245.8 cc) |
| Bore x Stroke | 2.375 in x 1.700 in (60.3 mm x 43.2 mm) |
| Fuel-to-Oil Ratio | 24:1 (1 quart of TC-W3 marine oil to 6 gallons of regular unleaded gasoline) |
| Fuel System Type | Two-line pressurized fuel system (requires pressurized tank) |
| Weight | 67 lbs (approx. 30.4 kg) |
| Cooling System | Water-cooled (positive displacement impeller pump) with thermostat control |
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2. Common Maintenance & Tune-Up Specs
To keep the 1958 Sportwin running smoothly, routine ignition, carburetion, and cooling system maintenance must be performed according to original Outboard Marine Corporation (OMC) standards.
Ignition System Specs (OMC Universal Magneto)
- Spark Plugs: Champion J4C (modern replacement) or Champion J6C (slightly hotter plug, excellent for prolonged trolling to prevent fouling).
- Spark Plug Gap: 0.030 inches (0.76 mm)
- Breaker Points Gap: 0.020 inches (0.51 mm)
- Condenser Capacity: 0.18 to 0.22 microfarads
- Ignition Coil: Standard vintage OMC epoxy/plastic-molded coils. Original coils are prone to cracking over time; replace with modern epoxy-sealed aftermarket coils (Sierra Part #18-5181) for reliability.
Carburetor Adjustments
The Tillotson or OMC-designed carburetor on this motor features adjustable low-speed (idle) and high-speed needles. Unlike modern fixed-jet carburetors, these must be tuned manually:
- High-Speed Needle (Bottom Knob): Gently turn clockwise until seated, then back out 3/4 to 1 full turn. This is the starting point. Adjust under load at wide-open throttle (WOT) for maximum RPM and smooth running.
- Low-Speed Needle (Top Knob): Gently turn clockwise until seated, then back out 1-1/2 turns. Adjust with the motor idling in forward gear until a stable, low idle is achieved without spitting or stalling.
Lower Unit & Cooling System Specs
- Gearcase Lubricant: Use OMC/BRP Hi-Vis Premium Lower Unit Lube or any high-quality marine 80W-90 hypoid gear oil. Do not use modern synthetic oils containing additives that may degrade the internal yellow metals (bronze bushings).
- Water Pump Impeller: Sierra Part #18-3001 (OMC OEM Part #377127). The water pump is located inside the lower unit housing above the gearcase. It should be inspected annually and replaced every two seasons to prevent overheating.
- Thermostat: The 1958 model features an integrated thermostat (opening at roughly 140°F) to ensure the engine warms up to operating temperature, minimizing carbon buildup. Verify operation if the motor runs unusually cold or hot.
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3. Notable Features & Historical Context
The 1958 Evinrude Sportwin was produced during a transition period in outboard history. It holds a special place in engineering design for several reasons:
The Two-Line Pressure Tank System
Unlike modern outboards that use a vacuum-pulse fuel pump to draw fuel from a single-line tank, the 1958 Sportwin uses a pressurized fuel delivery system.
The motor pumps pressurized air from the crankcase down into the fuel tank through one line, which forces fuel up to the carburetor through the second line.
- Safety Note: These tanks (typically OMC “Mile-Master” tanks) must be completely airtight to work. If you plan to run this motor today, you must either rebuild the vintage dual-line tank seals or convert the motor to a single-line fuel pump system using a vacuum pulse fuel pump (such as a Mikuni or later-model OMC fuel pump) driven off crankcase pressure.
“Whispering Power” Cushion Mounting
Evinrude’s hallmark marketing campaign in the late 1950s was centered on quiet operation. The 10 HP Sportwin featured a slip-in-shroud design where the powerhead was completely isolated from the lower mounting brackets by heavy-duty rubber mounts. This prevented engine vibrations from transferring to the boat hull, which acted as a sounding board, making the 1958 model one of the quietest running outboards of its era.
Aesthetics & Styling
With its iconic Holiday Blue and white color scheme, accented by polished aluminum trim and script lettering, the 1958 Sportwin is a prime example of mid-century industrial design. The pressure-cast aluminum cowl is a “two-piece” clamshell design held together by spring-loaded latches, allowing quick, tool-free access to the spark plugs and carburetor adjustments.
Whether you are restoring a vintage aluminum runabout or maintaining a family heirloom, the 1958 Evinrude 10 HP Sportwin remains a remarkably reliable, serviceable, and pleasant motor to run on the water when properly tuned to these specifications.