85
Installation
1. Lube the small end of the LEV/VSK camshaft and a
new cam bushing liberally with oil. (Never reuse cam
bushings once removed).
2. With the strength of your hand, place a new cam
bushing on the corresponding end of the camshaft and
press the bushing into the cam until flush with the
casting.
VALVES
The valves should be checked for proper clearance, sealing,
and wear. Valve condition is critical for proper engine
performance. Valve clearance should be checked before
removal from the engine block if a valve problem is
suspected or when the valves or seats are recut.
Valve clearance (between the valve stem and valve lifter)
should be set or checked when the engine is cold. The
piston should be at T.D.C. on the compression stroke (both
valves closed).
Use a valve grinder or "V" block to hold the valve square
when grinding the valve stem to obtain the proper clearance
(diag. 43).
When servicing the valves, all carbon should be removed
from the valve head and stem. If the valves are in a usable
condition, the valve face should be ground using a valve
grinder to a 45 degree angle. If after grinding the valve face
the margin is less than 1/32 of an inch (.793 mm), the
valve should be replaced (diag. 43).
Valves are not identical. Valves marked "EX" or "X" are
installed in the exhaust valve location. Valves marked "I"
are installed in the intake valve location. If the valves are
unmarked, the nonmagnetic valve (head) is installed in the
exhaust valve location.
To reinstall the valves, position the valve caps and springs
in the valve compartment. If the spring has dampening coils,
the valve spring should be installed with the dampening
coils away from the valve cap and retainer (diag. 44).
Install the valves into the guides making sure the correct
valve is in the proper port. The valve stem must pass through
the upper valve cap and spring. Hook the valve spring
retainer on the groove in the valve stem and release the
spring tension to lock the cap in place. Early models may
have a pin through the valve stem. Compress the spring
and cap and use a needle nose pliers to insert the pin in
the valve stem hole. Release the spring and check that
the pin is locked under the cap.
Emissionized engines have a valve stem seal on the intake
valve which prevents excess oil vapor from entering the
combustion chamber. This vapor would produce an
unsatisfactory exhaust emission and fail today's CARB
and EPA emission standards.
Tecumseh's position on emissionized engines is that
oversized valves are not necessary. The emissionized valve
with the valve stem seal should last the life of the engine.
Therefore, seals for oversized valves do not exist for our
small frame engines. Replacement of this seal is necessary
if valves have been removed for service.
NOTE: If the spring has dampening coils, they always go
toward the stationary surface.
DAMPENING COILS
LOCATED CLOSER
TOGETHER
42
43
44
SPRING MUST BE SQUARE
WRONG
FACE
RIGHT
INTAKE VALVE STEM SEAL (EMISSIONIZED ENGINES)
41
45
LEV/VSK
CAMSHAFT
WITH EXHAUST
MCR
45
0
1/32"
(.793 mm)
STEM
MINIMUM
DIMENSION
MARGIN
FACE
EASY-OUT
LEV/VSK
CAMSHAFT
WITH EXHAUST
MCR
CAM
BUSHING
No.6
PLACE BUSHING
