It is the "Comet Engine Corp." in Madison, WI, the manufacturer of at least three 7-cylinder radial engines.

-In 1928, the 7-D model appears. This air-cooled engine gave 150 hp and had a displacement of 612 cu.in.

-Also in 1928, appears the 7-RA that gave 130 hp.

-And in 1929 came out the 7-E that gave 165 hp with the same displacement as the 7-RA.

"Comet"

-The above drawing is complemented with this photograph of the Comet engine, manufactured in Wisconsin around 1929.

"Comet engine with frontal exhaust manifold"

-This engine had a half-desmodromic valve actuation system, acting with a single push-pull control rod and a single rocker arm.

-Therefore the valves were aligned, the front one with the rear one.