This is the 4-cylinder engine of the Nash metropolitan.
The Nash Metropolitan small economy car was introduced in the United States and Canada in March 1954. Buildt in England by Austin to Nash specifications, the 85-in. wheelbase Metropolitan was offered in 2-door hardtop and convertible models.
The popular little Metropolitan (which was to continue through the 1962 model year) underwent major changes for 1956, as the 1500 series replaced the original 1200. In addition to styling improvements, including two-tone paint treatments, the horsepower of the 4-cyl. engine was boosted 24 percent. The final year for the Nash nameplate was 1957 as American Motors decided to drop both the Nash and Hudson names to concentrate on the compact Rambler, the Metropolitan was later sold under the name Austin.
Information taken from http://www.geocities.com