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Atomic 4 Specification and Feature Information

Note: This information is for historical reference only. The Atomic 4 engine is out of production and this information comes directly from Atomic-4 promotional literature. Most parts for the repair and upkeep of the Atomic 4 are still available. Please use the following links for information about currently available parts.

| Atomic 4 Common Parts Listing | Atomic 4 Online Parts Catalog with Diagrams |
| Used & Rebuilt Atomic 4 and Other Engines |

The Universal Atomic-4 a 100% marine engine, designed and engineered exclusively for powering the world's finest sailboats. Gasoline engines with stamina, service and reliability equal to diesel power.

Why select the Atomic-4?

  • Complies with all current U.S.C.G. regulations
  • Safely power over 40,000 sailboats
  • Universal assurance of excellence
  • Lower cost and fuel consumption
  • Long life and service when and where ever needed
  • U.S. build and comprehensive dynamometer tested

Smoothness you only enjoy from the wind, no noise, no smell, no problems. The ultimate in "Power for sail", Universal Atomic...there is no other.


  • Standard Equipment: Propeller coupling, hand sump pump, U.S.C.G. approved flam arrestor, lifiting ring, water pump, electric fuel pump, oil level gauge, crankcase breather, built-in reversing gear, automatic temperature control, instruction manual, threaded exhaust flange, and shifting lever.
  • Cylinder Block: Cast en-block with crankcase of marine chrome nickel alloy iron. Full lenght water jackets.
  • Cylinder Head: Marine chrome nickel alloy iron. head is detachable. Combustion chamber designed to obtain maximum power and economy from regular grade gasoline.
  • Crankshaft: High carbon steel. Fully counterweighted, statically and dynamically balanced for smooth operating. Has insert bearings.
  • Connecting Rods: Drop forged, high carbon steel, insert bearings, and floating type piston pin.
  • Oil Pan: One piece true marine type extending the full length of engine provides exteme rigidity.
  • Manifold: Water jacketed exhaust and intake manifold incorporated into one casting. Exhaust flange tapped 1-1/4" I.P.S.
  • Lubrication: Full pressure to main, connecting rod, idler gear stud, and camshaft bearings. Outside oil pressure adjustment. Large area oil suction screen.
  • Hand Sump Pump: Separate, for easy removal of crankcase oil.
  • Water Jacket Cover: Removable clean out and water distributing plate on the side of cylinder block.
  • Cooling: Rubber impeller water circulating pump standard. Water pump inlet 3/8" I.P.S.
  • Reversing Gear: Oversize ball bearing type, pressure lubricated. Large radial end thrust ball bearing for propeller thrust. Reverse gear band with molded asbestos lining, provides longer life.
  • Reduction Gear: Single step, internal helical and pinion type. Available in 2 to 1 ratio.
  • Carburetor: Updraft Zenith marine safety non-drip type with upturned air horn, fitted with Zenith U.S.C.G approved type flame arrestor and vacuum crankcase ventilator.
  • Electrical System: 12 volt system standard. 37 amp alternator, marine type. Transistorized voltage regulator. Starter equipped with solenoid for remote starting. Distributor has full automatic advance.
  • Propeller Rotation: Right hand propeller
  • Automatic Temperature Control: Automatic bypass type to assure efficient operating temperature.


  • Instrument panel, power take-off pulley on flywheel, on-board spare parts kit, hand starting crank, 55 ampere alternator, adjustable rubber mounts.


  • Engine Type: 4 cycle L Head
  • Number of Cylinders: 4
  • Displacement: 65 cu. in.
  • Bore: 2-9/16"
  • Stroke: 3-1/8"
  • Fuel: Leaded Regular Grade
  • Fuel Pump: Electric
  • Electric Starter: 12 Volt
  • Electric Alternator: 12 Volt, 37 Amp
  • Weight (lbs):
    • Direct: 310
    • Reduction: 330
    • V-Drive: 335
  • Propeller Couplings:
    • Direct: 3/4" - 7/8" - 1"
    • Reduction: 1" - 1-1/8"
    • V-Drive: 7/8" - 1"
  • Propeller Data:
    • Direct Drive
      • Light Boats: 10 x 7-3 Blade
      • Heavy Boats: 10 x 6-3 Blade
      • Auxiliaries: 12 x 6-2 Blade
    • Reduction Drive 2:1
      • Light Boats: 14 x 7-3 Blade
      • Heavy Boats: 15 x 6-3 Blade
      • Auxiliaries: 15 x 8-2 Blade

Propellers listed are suggested for average boats and not necessarily recommended for all hulls

| Atomic 4 Common Parts Listing | Atomic 4 Online Parts Catalog with Diagrams |
| Used & Rebuilt Atomic 4 and Other Engines |