S&S Cycle Big Twin Oil Pump Kits - Manual (Page 7)

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B. Use .125” (1/8”) drill bit to drill pressure relief hole
into gear cavity. See Picture 11. Apply grease to
bit and both sides of case and withdraw drill
frequently during procedure to clear chips.
CAUTION - Do not perform Step 3 on stock 1936-1969
crankcases or any crankcase with angled tappet
screen. Drilled passage will intersect tappet screen
oil passage resulting in loss of oil pressure. Loss of
oil pressure will likely result in serious engine damage
due to inadequate lubrication.
4. Optional Crankcase Modification - 1948-1962
Using #31-6001 cast or #31-6040 billet pump body,
or 1966-1969 using #31-6001 or #31-6073 cast pump
body - Plug and Redrill Crankshaft Feed Hole.
NOTES
● Objective of this modification is to alter 1948-1962
and 1966-1969 crankcases to 1973-later style oiling.
With this oiling system heads and lifters get primary,
unrestricted oil supply first. Lower end main and rod
bearings get secondary, low pressure oil after top end is
supplied. This modification is recommended only if
hydraulic lifters are used.
● 1948-1969 style S&S crankcases feature special
machining leaving installation of plug as described in
Section 4-D only step required to complete modification.
● 1963-1965 and other Panheads with outside oilers
cannot utilize Step #4, Optional Crankcase Modification,
due different oil supply system.
CAUTION - If performed on “outside oiler” Panheads,
modification described in Step 4 will result in oil
starvation to top end and extensive engine damage.
A. Wrap masking tape around .203" ( 13 ⁄
64
") drill bit .850"
from point to use as depth guide. Carefully drill hole in
Picture 12 .850" deep. See Pictures 12 and 13.
NOTE - Drill size is very close to hole size and may tend
to distort hole if drill is not steadied.
CAUTION - Distorting hole may cause poor thread fit
after hole is tapped.
B. Using 1 ⁄
4
-20 tap, carefully tap hole deeply enough
for 1 ⁄
4
-20 set screw provided in kit to bottom out
with screw head .540” to .600” below gear cover
gasket surface. See Pictures 14 and 15. Remove
tap periodically and install set screw to check depth.
NOTE - Do not tap hole deeply enough for set screw to
block tappet screen oil feed passage.This will restrict oil
supply to lifters and cylinder heads.
CAUTION - Restricted oil supply may cause extensive
engine damage.
C. On 1948-1952 crankcases blow air into
intersecting hole in pump gasket surface to
remove chips. On 1953-1969 crankcases
remove oil plug and lifter screen filter assembly
and blow air into passage to remove chips. See
Picture 16.
NOTE - Before blowing chips out, set screw must be
removed to allow them to escape.
WARNING - Compressed air and particles dislodged
by compressed air are potentially harmful. Wear
protective goggles when using compressed air and
always direct air stream away from yourself and
others nearby.
D. Apply Loctite to threads of 1 ⁄
4
-20 set screw provided
and install to depth of .540” to .600” below gear
cover gasket surface.
Picture 14 Picture 16 Picture 15