The Continental O-170 engine is the collective military designation for a family of small aircraft engines, known under the company designation of A50, A65, A75 and A80. The line was designed and built by Continental Motors commencing in the 1940s. It was employed as the powerplant for civil and military light aircraft.Christy (1983) The horizontally opposed, four-cylinder engines in this family are all identical in appearance, bore, stroke, dry weight, and piston displacement. All feature a bottom-mounted updraft carburetor fuel delivery system. The higher power variants differ only in compression ratio and maximum allowable rpm, plus minor modifications. The lower power versions are fully convertible to the higher rated versions.

Design and development

In all models of this family of engines the cylinder heads are of

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

alloy, screwed and shrunk onto

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

barrels.

Spark plug A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/air ...

inserts and intake valve seats are made from aluminum-

bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals (such as phosphorus) or metalloid ...

alloy, while the exhaust valve seats are steel. The engines all employ hydraulic tappets which operate in aluminum guides that are machined into the

crankcase A crankcase is the housing in a reciprocating engine, piston engine that surrounds the crankshaft. In most modern engines, the crankcase is integrated into the engine block. Two-stroke engines typically use a crankcase-compression design, res ...

. The tappets are built from four parts, a cam follower body, cup, cylinder, and piston and operate with clearances of to . The

pushrod A valvetrain is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) into the combu ...

s are steel and feature pressed-in ball ends. Lubricating oil is delivered under pressure from the oil sump to the drive bearings and the crankpins through the crankshaft. The cylinder walls and pistons are spray lubricated. Normal operating oil pressure is 35 psi, with minimum idle oil pressure 10 psi.

Variants

;A50 :, Compression ratio 5.4:1, max rpm 1,900, fuel consumption at cruise 3.8 US gph ;A50-1: ;A50-2: ;A50-3: ;A50-4: ;A50-5: ;A50-6: ;A50-7: ;A65 :, Compression ratio 6.3:1, max rpm 2,300, fuel consumption at cruise 4.4 US gph. The exhaust valves have

stellite Stellite alloys are a range of cobalt-chromium alloys designed for wear resistance. "Stellite" is also a registered trademark of Kennametal Inc. and is used in association with cobalt-chromium alloys. History Stellite was invented by Elwood Hay ...

faces. The pistons have three rings, although some early production A65s had four piston rings.Teledyne Continental Motors: ''Continental Aircraft Engine Operator's Manual'', pages 4-5. Teledyne Continental Motors, FAA Approved December 1980. Continental Form No. X30012 ;A65-1: ;A65-2: ;A65-3: ;A65-4: ;A65-5: ;A65-6: ;A65-7: ;A65-8: ;A65-8F: :A65-9: ;A65-12: ;A75 :, Compression ratio 6.3:1, max rpm 2,600, fuel consumption at cruise 4.8 US gph. The exhaust valves have stellite faces and the connecting rods have a hole drilled in the rod cap to improve lubrication. The pistons have three rings and smaller piston pins. ;A75-1: ;A75-2: ;A75-3: ;A75-4: ;A75-5: ;A75-6: ;A75-14: ;A80 :, Compression ratio 7.55:1, max rpm 2,700, fuel consumption at cruise 5.2 US gph. The connecting rods have a hole drilled in the rod cap to improve lubrication. The pistons have five rings and smaller piston pins. ;A80-1: ;A80-2: ;A80-3: ;A80-4: ;A80-5: ;A80-6: ;A80-8: ;O-170 :Military designation for the A50, A65, A75, A80 family of engines. ;O-170-1: ;O-170-3: ;O-170-5: ;O-170-7:

Applications

;A50 * Aeronca KCA * Aeronca 50C * Aeronca 50TC * Aeronca S50C *

Luscombe 8 The Luscombe 8 is a series of high-wing, side-by-side-seating monoplanes with conventional landing gear, designed in 1937 and built by Luscombe Aircraft. Development The XT8E was developed in 1947 to compete for an U.S. Air Force contract, ...

Piper J-3 The Piper J-3 Cub is an American light aircraft that was built between 1938 and 1947 by Piper Aircraft. The aircraft has a simple, lightweight design which gives it good low-speed handling properties and short-field performance. The Cub is Pi ...

* Piper J-4 * Porterfield CP50 * Porterfield CP55 * Taylorcraft BC * Taylorcraft BCS ;A65 ContinentalA65

;A75 * Bearhawk LSA * Culver LCA * Jodel D.121 * Luscombe 8C * Luscombe 8D * Piper J-4E * Piper J-5 * Piper J-5A * Porterfield 75C * Rearwin Skyranger 175 * Stinson Model 105 (HW-75) ;A80 * Harris Geodetic LW 108 * Piper J-5A-80 *

Shirlen Big Cootie The Shirlen Big Cootie is an American homebuilt biplane that was designed by Roy Shirlen. Design and development The Big Cootie is a modernized version of the Powell PH Racer biplane for homebuilt construction. The aircraft is a single seat bip ...

* Stinson Model 105 (HW-80) * Stinson Model 10 *

Vought V-173 The Vought V-173 "Flying Pancake" is an American experimental test aircraft built as part of the Vought XF5U program during World War II. Both the V-173 and the XF5U featured an unorthodox "all-wing" design consisting of a flat, somewhat disk- ...

Specifications (O-170-3 or A-65-8)

Notes

References