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Section 4 Engine Service
Caps must never be switched from one rod to another.er.thano
Frequently, locking devices are installed on the
rod cap to stop connecting rod bolts or cap screws
from loosening in service. One common device
is a thin sheet metal strip with locking tabs. See
Figure 19-19. The cap screw is inserted through
holes in the locking strip, holding it in place against
the rod. After the cap screw is tight, the metal tabs
are bent up against the fl at sides of the screw head.
Self-locking nuts, lock washers, and specially
shaped cap screws are also used to prevent loosen-
ing. The fi nal tightening of the cap screws is espe-
cially important. Always use a torque wrench to
tighten rod fasteners to the exact torque specifi ed
by the manufacturer.
Installing Overhead Valves
Before starting assembly of an overhead valve
cylinder head, inspect valve stems for foreign
material and burrs, which can cause sticking and
damage the new stem seals. Coat the valve stems
with valve guide lubricant. Do not allow the lubri-
cant to contact the valve face, valve seat, or end
of the valve stem. Install the valves in the cylin-
der head, being careful to install the intake and
exhaust valves in their respective guides.
Caution
Caps C Ca a p s must m m us never ne e be e switched i f rom one ro d t o C C C t b i i t h d f d t th
Figure 19-17.
Lubricate the connecting rod bearing surfaces and
the crankshaft journals with assembly lube before
installing the rod cap. A—Assembly lube being applied
to rod cap. B—Rod cap installed on rod.
A
B
Figure 19-18.
Connecting rod cap installation. A—If the cap is turned
180°, the rod bore will be offset. B—The match marks
on the rod and cap signal correct assembly.
A B
Incorrect
correct
Cap
reversed
Match
marks
Figure 19-19.
A locking plate is often used between the connecting
rod cap and cap screws. (Tecumseh Products Co.)
Match marks
Locking plate