Knucklehead left side engine crankcase 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 1936-1942 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
Left side cases accept standard case race
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
