Two companies built Sandow engines, beginning with Sandy McManus Inc., of Waterloo, Iowa, organized in 1912, which built Dave Hills’ 1912 6 HP Sandow engine. The company built Sandow, as well as Power King engines, until 1915, when Sandy McManus resigned as company head to pursue “the broader field of automobiles,” according to C. H. Wendel in American Gasoline Engines Since 1872.
The company reorganized as the Interstate Engine & Tractor Co. and morphed into the Plow Man Tractor Co. in 1919, which lasted only until 1920.
Detroit Motor Car Supply Co., of Detroit, also built another line of Sandow-named engines, starting in 1913, with a 2-1/2 HP vertical. It is unrelated to the Sandy McManus Inc. company, and it is unclear how long DMCSC lasted, but apparently not long.
For more on the Sandow engine, go to 1912 6 HP Sandow Stuns at Show.