Left Side Engine Case

Knucklehead left side engine case is sand cast as original, number boss is blank. The case has updated design to accept 1940-1954 case bushing.
The serial number pad is 5/16" wide and 2-1/4" long, and the 1936-42 pads features two lugs on the pad as on 1936-1940 models. Case must be fit to builder's right hand case. Fitting the case to your existing case may require machining and/or adding material on motor mount surfaces, beside the deck height of the cylinder spigot area. This is not a "bolt on " component. Deck height must be milled to fit. Accepts 61" flywheels. Case set required line lapping of the main case races. Order case race available separately. Baffles cast in at cylinder base area. *NOTE: Left side cases accept standard case race. **NOTE: Short rib case used 1936 - mid 1961. Last 1941 production thru 1947 have the high rib, for the added strength needed for 74 cubic inch. *NOTE: It is important to match case to the existing case. It will require machine work and possible welding of addtional material for final fitting.