According to the Johnson motors service manual QD-13 is a 1952. Original list price at $295. It has a two and three eights inch bore and a one and seven eights inch stroke. It is listed as a 10 horse at 4000 RPM. The spark plug would be a champion J-6-J. Cubic inch is 16.6 and it weighs 58 pounds. Hope this helps.
Nice motor!