Tecumseh HH100 Handbook page 30

VALVE REMOVAL PROCEDURE FOR VALVE-IN-
HEAD ENGINES.
The following is necessary for cylinder head disassembly.
REMOVAL OF ROCKER ARM HOUSING PARTS.
Locate the piston at top dead center for easier access
in servicing the valve train. After removing the rocker
arms by removing the retaining rings, it may be necessary
to loosen the locknut and back off the adjusting screw
before pulling off the rocker arms. NOTE: Rocker
arm shaft is not an inseparable unit from the rocker
arm housing and should not be removed from the
housing.
UPPER VALVE
LOWER VALVE
SPRING CLIP
SPRING CAP
VALVE SPRING
REMOVAL OF VALVE SPRINGS. Use a valve spring
compressor tool, part No. 670237A to compress the
valve spring and remove the valve retainers. Be sure
piston is at T.D.C. The valve cap is then taken off
for removal of the spring. When reinstalling the valve
cap and retainers after valve servicing, it may be
necessary to hold both valves in their seats until
the springs, cap, and retainer have been installed
on the valve stems. Access can usually be gained
through the exhaust and intake manifold in the head.
RETAINERS HELD BY SPRING
TENSION AGAINST THE CAP
CAP
28
PUSH RODS
ROCKER ARM SHAFT
RETAINER
VALVE SPRING
COMPRESSOR TOOL
PART NO. 670237A
REMOVAL OF ROCKER ARM HOUSING. Remove
rocker arm housing by removing the retaining cap
screws. The valve spring retainer cupped side must
be facing in the up position.
A white Teflon "O" Ring is used under the valve spring
retainer on the exhaust valve. The regular black rubber
"O" Ring is used under the valve spring retainer on
the intake valve. Be careful not to switch rings, or
damage may result.
Remove head to remove the valves - Reverse procedure
for reassembly.
VALVE SPRING
RETAINER
ROCKER ARM HOUSING RETAINING SCREWS,
WASHERS AND SEALING "O" RINGS
ROCKER ARM SHAFT. The rocker arm shaft is not
a replaceable part. The rocker arm housing, rocker
arm shaft and screw are an inseparable assembly.
ROCKER
ARM SHAFT
RETAINING
SCREW
VALVE SPRINGS FREE LENGTH
FOR 8 HORSEPOWER AND LARGER ENGINES
(EXCEPT VALVE-IN-HEAD ENGINES). Valve springs
should be replaced when an engine is overhauled.
Weak valve springs will spoil the best overhaul job.
Valve spring free length should be checked. Comparing
one spring with the other can be a quick check to
notice any difference. If a difference is noticed, carefully
measure free lengths and strength of each spring.
See specifications.
Check valve spring free length, it should be 1.885''
(47.879 mm). If both ends are not parallel, replace
with new springs.
"O" RING
CHAMFER