Your 1939 Sportwin has a bore of 1.75" and a stroke of 1.375" for a piston displacement of 6.6 cubic inches. It develops 3.3 horse power @ 3,500 RPM. The fuel tank holds 6.5 pints, the oil to gas mix is 1/3 of a pint to the gallon (1 to 24 ratio) The 132584 shear pin is a3/16" diameter number 3 shear Aluminum rod 15/16" long. The two bladed aluminum semi-weedless propeller has a diameter of 7.5" and pitch of 6". The gears are lubricated by Grease as he cork seals are not the best, but better than nothing. Hope this helps . . . 😀
You will note that the 121020 feeler gauge in the tool kit shown o page 4 has a spark plug end of 0.025" & breaker point end of 0.020"
Starting and operating instructions
The factory specified Champion H10J spark plug has been replaced by there CJ8 – check website for latest numbers
The float may be replaced by modifying Mercury 1395-8983 (NAPA 18-7308)
Carburetor specifications –
