1955 Evinrude 7.5 HP Fleetwin Outboard Specs & Part Numbers
Introduction to the 1955 Evinrude 7.5 HP Fleetwin
The 1955 Evinrude 7.5 HP Fleetwin (Model 7518/7519) represents a golden era in American marine engineering. Positioned perfectly between the lightweight 3 HP Lightwin and the larger 15 HP Fastwin, the 7.5 HP Fleetwin was the quintessential family outboard of the mid-1950s. Highly regarded for its portability, smooth power delivery, and full gearshift capabilities, it remains a favorite among vintage outboard collectors and restorers today.
Overview & Specifications
The Fleetwin was designed to power small family runabouts, fishing boats, and rowboats. It utilized a robust two-cylinder, two-stroke powerhead that delivered an exceptional power-to-weight ratio for its time. Below are the complete factory specifications for the 1955 model.
| Specification | Detail / Value |
|---|---|
| Model Number(s) | 7518 (Standard Shaft), 7519 (Long Shaft) |
| Horsepower Rating | 7.5 HP @ 4,000 RPM |
| Engine Type | 2-Cylinder, 2-Stroke, Alternate Firing |
| Displacement | 12.4 cu. in. (203.2 cc) |
| Bore x Stroke | 2.125″ x 1.750″ (53.97 mm x 44.45 mm) |
| Weight | 49 lbs (22.2 kg) |
| Fuel/Oil Ratio | 16:1 (1/2 pint of TC-W3 or SAE 30 outboard oil per 1 gallon of regular gasoline) |
| Fuel Delivery | Cruis-a-Day Pressurized 2-Line Fuel System |
| Starter System | Simplex Manual Recoil Starter |
Crucial Fuel Ratio Note: Modern 50:1 fuel-to-oil ratios will quickly ruin this motor. The 1955 Fleetwin utilizes bronze wrist-pin bushings and babbitt bearings rather than modern needle bearings. It requires a heavy oil film to prevent friction wear. Always run a 16:1 fuel ratio to ensure powerhead longevity.
Common Maintenance & Tune-up Specs
Maintaining a vintage Fleetwin is relatively straightforward thanks to its simple design and the excellent availability of reproduction parts. To keep your ’55 Evinrude running reliably, adhere to the following ignition, fuel, and cooling system specifications.
Ignition System (OMC Universal Magneto)
The 1955 Fleetwin uses the legendary OMC Universal Magneto system. If you have weak or no spark, the coils are the most common culprit, as the original vintage coils tend to crack and fail over time.
- Spark Plug Type: Champion J6C (historically J6 or J11J)
- Spark Plug Gap: 0.030″ (0.76 mm)
- Point Gap Setting: 0.020″ (0.51 mm)
- Condenser Capacity: 0.18 to 0.22 microfarads
Carburetor Adjustments
The carburetor features high-speed and low-speed adjustable packing glands. If starting from scratch after a rebuild, use these baseline settings:
- High-Speed Needle (Bottom): Gently seat clockwise, then open 3/4 to 1 full turn out.
- Slow-Speed/Idle Needle (Top): Gently seat clockwise, then open 1-1/2 turns out.
- Note: Fine-tune both needles on the water under load with the engine at operating temperature.
Gearcase & Cooling System
- Water Pump Impeller: Part number 375683 (or Sierra 18-3001). Inspect the water pump housing for score marks; replace if worn to ensure strong cooling flow.
- Lower Unit Lubricant: Standard Marine Gear Lube (such as Lubriplate Hypoid 90 or OMC/Evirude Hi-Vis).
- Gearcase Capacity: Fill from the bottom drain plug until grease expels from the top vent plug. Approximately 5.5 to 6 oz.
Notable Features & History
The Cruis-a-Day Pressurized Fuel System
Like most OMC outboards of the mid-1950s, the 1955 Fleetwin did not feature an integrated mechanical fuel pump. Instead, it relied on a pressurized “Cruis-a-Day” two-line fuel tank system.
One line from the engine pumps air pressure into the fuel tank, while the second line pushes fuel up to the carburetor under pressure. While highly reliable when properly sealed, owners must ensure that the rubber gaskets on both the motor connectors and the tank lid are in pristine, airtight condition. Warning: Never use a modern single-line tank with this motor unless you have installed an aftermarket vacuum-operated pulse fuel pump conversion.
Full Gearshift Capability
Unlike earlier utility outboards that required you to swing the entire motor 180 degrees to go backward, the 1955 Fleetwin features a robust mechanical gearshift with true Forward-Neutral-Reverse (F-N-R) shifting. This added unprecedented safety and dockside maneuverability for small-craft operators of the era.
Duo-Flex Copilot and Whisper Power
In 1955, Evinrude heavily marketed their “Whisper Power” design. The powerhead was isolated from the lower mounting brackets using thick rubber vibration dampers. This decoupled the motor’s vibration from the boat’s transom, dramatically reducing hull noise. Additionally, the Duo-Flex copilot steering system provided automatic tensioning to keep the motor tracking straight when the operator let go of the tiller arm.
Collectibility & Restoring a Classic
Today, the 1955 Evinrude 7.5 HP is highly sought after by restorers. Its striking “Aquasonic Blue” hood with polished aluminum trims makes it a standout piece of mid-century industrial art. Because OMC sold tens of thousands of these units, mechanical components such as points, condensers, carb kits, and impellers are still mass-produced and readily available at local marine parts counters, making it the perfect first-time project for vintage outboard enthusiasts.