S&S Cylinder and Piston kits for 1936-'47 big twins feature premium quality U.S. made S&S cylinders and S&S forged 3-7/16" bore 74" pistons. The cylinders are cast from high strength engineering grade grey iron for superior wear resistance and heat dissipation, and are finished with durable gloss black high temp powder coat. These cylinders have been designed to look as much like OEM knuckle cylinder as possible.
S&S® cylinder heads for 1940-’47 OHV big twins are machined for 7/16-20 head bolts and are not compatible with stock 7/16-16 head bolts. If using S&S heads with 37/16" bore cylinders, stock style
hex head bolts for 1948-’65 big twins, part #106-4523 may be used. S&S 35/8" bore cylinders require the use of S&S 1966-'84 style 12 point head bolts part #93-3024, due to clearance issues.
Stock 1930-’78 hex style base nut kit is available in cadmium plate, part #106-4522, for 37/16" bore cylinders only. Stainless raised hex base nuts, part #93-3063-S, are required for 35/8" bore cylinders.