Universal Atomic 4
The Universal Atomic 4 is a four-cylinder, gasoline engine produced by the Universal Motor Company between 1949[1] and 1984 for use as auxiliary power on sailboats.[2] Both 18 horsepower (13 kW) and 30 horsepower (22 kW) versions of the engine were produced.[3] Over 40,000 of the engines were produced during that time, with an estimated 20,000 still in use today.
The Universal Atomic 4 was very popular in Catalina Yachts sailboats, up through 1985. Starting in the early 1970s the brand Yanmar became very popular as an auxiliary power diesel engine for sailboats, in response Universal began offering a marinized version of a Kubota diesel (tractor) engine in 1976, which was popular with sailboat manufacturers, in particular Catalina. As Yanmar diesel engines continued to gain in popularity, the Universal Atomic Four gasoline engines continued to lose market share rapidly. By 1989 Yanmar had eclipsed Universal in the diesel auxiliary market with 45% market share to 42% for Universal.
History and Lineage
The Atomic 4 is descended from an earlier Universal Motor Company design called the Utility Four,[4] which was used extensively in World War II by the United States Navy and allies to power lifeboats.[5] The Utility Four was replaced by the Atomic 4 in 1947.[6]
Applications
- Alberg 30
- Bristol 40
- C&C 35
- C&C 27
- C&C 29
- C&C 30
- C&C 33
- C&C 34
- C&C 38
- C&C 39
- Cal 28
- Catalina 27
- Catalina 30
- Catalina 38
- Chance 32/28
- Columbia 33 Caribbean
- Columbia 34
- Columbia 34 Mark II CB
- Columbia 34 Mark II SD
- Corvette 31
- Ericson 27
- Frigate 36
- Grampian 30
- Irwin 27
- Invader 36
- Morgan Out Island 28
- Morgan 34
- Newport 27
- Newport 30
- Pearson 28
- Pearson Triton
- Pearson Renegade
- Ranger 29
- Pearson Ariel
- Pearson Wanderer
- Pearson Vanguard
- Ranger 28
- Ranger 32
- Ranger 33
- Ranger 30
- Redline 41
- Southern Cross 28
- Soverel 36
- Tartan 30
- Tartan 34 C
Specifications
| Engine Type | Four Cylinder, Vertical, 4 Cycle, L-Head |
|---|---|
| Bore | 2 9/16" x 3 1/8" |
| Displacement | 64.46 Cubic Inches |
| Compression Ratio | 6.3:1 |
| Engine Rotation | Counter-clockwise from flywheel end |
| Firing Order | 1-2-4-3 (no. 1 on flywheel end) |
| Reduction Gear Ratio | 2.04:1 or direct 1:1 drive |
| Maximum Operating Angle | ~15 degrees |
| Fuel | regular leaded gasoline (will function on unleaded fuel with precautions) |
| Lubrication Oil | SAE 30 |
| @ RPM | 600 | 1000 | 1500 | 2000 | 2500 | 3000 | 3500 |
|---|---|---|---|---|---|---|---|
| Brake Horsepower: | 5 | 7.3 | 11.9 | 16.2 | 20 | 25 | 30 |
References
- MotorBoating. May 1981. pp. 112–. ISSN 1531-2623.
- MotorBoating. August 1976. pp. 49–. ISSN 1531-2623.
- MotorBoating. November 1965. pp. 52–. ISSN 1531-2623.
- MotorBoating. April 1981. pp. 134–. ISSN 1531-2623.
- Thomas Fleming Day (1942). The Rudder. Fawcett Publications.
- Stan Grayson (1 October 2008). American marine engines 1885-1950. Devereux Books. ISBN 978-1-928862-13-0.