From Hallett Aero Motors Corp, in Inglewood, CA., we know the Hallett H-526 that was built in 1928.

“Hallett H-526”

-It had 7 air-cooled, radial cylinders. It gave 130 hp at 1,800 rpm.

-It had two Zenith carburetors and Splitdorf magnetos.

-Other information gives us Hallett as the Hallett Manufacturing Co. in Los Angeles, and their engine with seven radial cylinders giving 130 hp.

“Hallet, 130 HP, front view”