Harley Davidson motorcycles 1940 to 1947 inclusive O.H.V. engine / side valve engine. Service Manual - page 3
LEGEND FOR ILLUS. 22 AND 23 O.H.V. ENGINE OILING AND BREATHER SYSTEM
Note: Oil to rocker arms and valve stems is metered
through a fixed orifice in each rocker arm shaft and no adjustment for
more or less oil is provided.
CAUTION: Since oil supplied to overhead fittings is sucked back into
crankcase through push rod covers by crankcase vacuum, it is essential
that push rod covers and rocker arm housings be well sealed to maintain
maximum vacuum and prevent oil leakage. When reassembling push rod
covers, make sure that both ends of covers are properly seated against
cork washers.
