Valves - Tecumseh ECV105 Technician's Handbook

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. 40).
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. 41).
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. 42).
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.
NOTE: If the spring has dampening coils, they always go
toward the stationary surface.
WRONG
RIGHT
MARGIN
1/32"
(.793 mm)
MINIMUM
DIMENSION
STEM
SPRING MUST BE SQUARE
FACE
40
45
0
FACE
41
DAMPENING COILS
LOCATED CLOSER
TOGETHER
42
85