Evinrude 4906B 4HP 1969, Owner'S Manual

Page: 66 / 422

Therefore, the rod and piston MUST be
assembled correctly in order for the as-
sembly to be properly installed into the
cylinder. Soak the piston in a container of
very hot water for about ten minutes.
Heating the piston will cause it to expand
ever so slightly, but enough to allow the
wrist pin to be pressed through without
dif
f
icul
ty,
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 cape
with needle bearing grease, or a
goal
grade
of petroleum jelly. Load the bearing caze
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 a'nd the hole in
the rod is facing upward.
Place the piston and rod in the arbor
press with the LOOSE or stamped "Lit side of
the piston facing UPWARD. Press the wrist
pin through the piston and rod. Continue to
press the wrist pin through until the groove
in the wrist pin for the lock ring is visible on
both ends of the pin.
Remove the assembly
from the arbor press. Install the retaining
ring onto each end of the wrist pin. Some
models have a wire ring, and others have a
truarc ring. Use a pair of truarc pliers to
install the tr uar c ring.
Fill the piston skirt with a rag, towel,
shop cloths, or other suitable material. The
The slanted side
of
the piston
MUsr
face the
exhaust port and the sharp edge face the intake port.
RODS AND PISTONS 3-25
WORD
IIlOOSE-'
Wrist pin entering the piston from the
1/
LOOSE"
side.
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.
Alternate Assembling Method
If an arbor press is not available, the
piston may be assembled to the rod in much
the same manner as described for disas-
sembling.
Heating the piston in hot
water to
expand the metal
slightly as an assist
to
installing the wrist pin.