Evinrude 4906B 4HP 1969, Owner'S Manual

Page: 67 / 422

3-26 POWERHEAD
First, soak the piston in a container of
very hot water for about ten minutes.
Before pressing the wrist pin into place,
hold the piston and rod near the cylinder
block and check to be sure both will be
facing in the right direction when they are
installed.
Pack the wrist pin needle bearing cage
with needle bearing grease, or a good grade
of petroleum jelly. Load the bearing cage
with needles and insert it into the end of the
rod.
Slide the rod into the piston boss and
check a second time to be sure the slanted
side of the piston is facing toward the
exhaust side of the cylinder and the hole in
the rod is facing upward.
Now, assume a sitting position and lay a
couple towels over your lap. Hold your legs
tightly together to form a cradle for the
piston above your knees. Set the piston
between your legs with the
LOOSE
side of
the piston facing upward. Now, drive the
wrist pin through the piston using a drift pin
with a shoulder. The drift pin will fit into
the hole through the wrist pin and the
shoulder will ride on the end of the wrist
pin. Use sharp hard blows with a hammer.
Your legs
will
absorb the shock without
damaging the piston. If this method is used
on a regular basis during the busy season,
your legs will develop black-and-blue areas,
but no problem, the marks will disappear in
a few days.
Continue to drive the wrist pin through
the piston until the groove in the wrist pin
for the lockring is visible at both ends.
Install the retaining spring wire or truarc
ring onto each end of the wrist pin.
Install ing the rod and wrist pin bearing into the
piston.
DRIFT
PIN
HOLDING
BLOCK
Install the wrist pin using
a
holding block.
F ill the piston skirt with a rag, towel,
shop cloths, or other suitable material. The
rag will prevent the rod from coming in
contact with the piston skirt while it is
laying on the bench. If the rod is allowed to
strike the piston skirt, the skirt may become
distorted.
Assemble the other pistons, rods, and
wrist pins in the same manner. Fill the skirt
with rags as protection until the assembly is
installed.
Installing the wrist pin without an arbor press. The
piston can be held in your lap as described in the text.