Franklin Aircraft Engine 4AC-150

The Franklin O-150 (company designation 4AC-150) was an American air-cooled aircraft engine of the late 1930s (first run in 1938). The engine is of four-cylinder, horizontally-opposed layout with a displaced of 150 cubic inches. The first model used a single magneto. This engine has dual magnetos.

This engine was used on a number of light aircraft in the 1930s including:

Aeronca 50 Chief
Piper J-3 Cub
Rose Parakeet
Taylorcraft BF-50

This engine was restored in 2019 to running condition by the students of instructor Paul Agaliotis at Gavilan College’s A&P school of Gilroy, California.

Check out the video of a test run

 

Engine Name
Franklin 4AC-150
Specifications
Manufactured by:Aircooled Motors
Cylinder Configuration
opposed (flat)
Number of Cylinders
4
Bore (inches)
3.625
Stroke (inches)
3.625
Displacement (cubic inches)
149.6
Fuel Type
gasoline
Electrical
magneto with dual spark ignition
Horsepower (max for T.O.)
50
Rated RPM
3,500
Compression Ratio
6.66:1
Cooling System
air-cooled
Dry Weight (lb)
155
Fuel Consumption (gph) 4.4