Gale Model 25DEL20 Outboard Motor Specs & Overview

Overview of the Gale 25 HP Outboard Motor (Model 25DEL20)

Gale Products, a division of the Outboard Marine Corporation (OMC), played a pivotal role in the mid-century recreational boating boom. Positioned as a practical, high-value alternative to OMC’s flagship Johnson and Evinrude lines, Gale outboards shared many of the same robust internal components and proven powerhead designs. The Gale Model 25DEL20 is a classic 25-horsepower twin-cylinder engine built on OMC’s famous 35.7 cubic-inch platform. Featuring electric starting capabilities, full gearshift, and standard OMC reliability, it remains a favorite among vintage outboard collectors and restorers today.

Key Technical Specifications

• Model Name: 25DEL20
• Horsepower: 25.0 HP @ 4,500 RPM (O.B.C. Certified)
• Operating RPM Range: 4,000 – 5,000 RPM
• Engine Displacement: 35.7 cubic inches
• Cylinder Configuration: 2-cylinder, alternate firing
• Bore and Stroke: 2-7/8″ bore x 2-3/4″ stroke
• Powerhead Design: 2-cycle, 2-port
• Starter System: Electric starting with manual automatic rewind backup
• Gearshift Control: Full Forward – Neutral – Reverse (F-N-R)
• Gear Ratio: 12:21
• Propeller: 3-blade, 10-3/8″ diameter x 12-1/2″ pitch
• Cooling System: Rubber blade combination displacement and centrifugal water pump
• Ignition System: Built-in flywheel magneto
• Carburetor: Float feed with adjustable high- and low-speed needle valves
• Speed Control: Synchronized spark and throttle with twist-grip handle
• Fuel System: 6-gallon remote fuel tank
• Weight: 126 lbs. (without fuel tank)
• Transom Height Compatibility: 15″ standard or 20″ long shaft options

Two-Stroke Fuel Mixture & Gasoline Guidelines

Due to the bearing tolerances and design of 1950s and 1960s OMC powerheads, maintaining the correct oil ratio is critical to preventing internal engine damage. Use a 24:1 fuel-to-oil mix ratio: 1 quart of high-quality TC-W3 marine two-stroke oil per 6 gallons of gasoline (or 16 oz per 3 gallons).

Always use ethanol-free gasoline whenever possible. Modern ethanol-blended fuels can quickly deteriorate vintage rubber fuel lines, fuel pump diaphragms, and carburetor float bowls, while also attracting moisture into the fuel system during storage.

Maintenance & Restoration Advice

Servicing the Gale 25DEL20 is relatively straightforward thanks to parts crossover with contemporary 25 HP Johnson and Evinrude models of the same era. When undertaking a restoration or seasonal overhaul, pay close attention to these vital systems:

• Ignition Overhaul: The universal OMC flywheel magneto uses dual coils, points, and condensers. Original vintage coils frequently crack due to age and heat. Replace cracked coils with modern reproduction OMC universal coils, replace the condensers, and set both ignition point gaps to exactly .020 inches.
• Cooling System: Never run the engine out of water, even briefly. The lower unit houses a flexible rubber impeller water pump. Inspect and replace the impeller prior to putting a restored motor back into service, as dry rot and hardened rubber blades will quickly cause overheating.
• Carburetor Tuning: Remove and soak the carburetor body to clear clogged fuel passages. When reinstalling, set the initial baseline adjustments for both the high-speed and low-speed needle valves to 1 to 1.5 turns out from light seat, then fine-tune under load while testing on the water.
• Lower Unit Lubrication: Drain the lower unit oil to check for water intrusion (indicated by a milky emulsion). Replace the drain/fill plug washers and refill with fresh marine gear lube. If water is present, rebuild the propeller shaft and drive shaft seal assemblies.
• Electrical System: Check all heavy-gauge starter wiring and ground contacts. Ensure the starter solenoid circuit is clean and fused to prevent damage to the vintage starter motor.