This engine was rebuilt from WWI surplus French Salmson Z-9. The Z-9 was a nine cylinder water cooled radial rated at 230 hp to 280 hp.
Waldo Waterman was the first to convert one of these engines to air cooled. According to Waldo Waterman's book "Waldo", these engines were available for $90 each. Waldo Waterman converted one of the Z-9s to air cooling by cutting off the water jacket and brazing on copper fins. Waldo expected to sale these engines for about $1000. This is to be compared to the cost of a new Wright, which were $5000 and up.
Al Menasco obtained the principal assets of the estate of Art Smith, a warehouse full of 250 WW I surplus Salmson Z-9. Art Smith died February 12, 1926 near Montpelier, Ohio while flying air mail.
Al Menasco made cast aluminum head for his conversion.
Menasco could not get the Menasco-Salmson B-2 to pass the 50 hr full power test required to obtain a ATC. It failed the test five times, getting to 49.5 hr before the crankcase failed on the last test.
Article from Aviation Week July 9, 1928 about the Menasco-Salmson B2
Menasco-Salmson B-2 Applications