Tecumseh HH100 Handbook page 31

VALVE INSTALLATION. To reinstall valves, position
valve caps and spring in the valve compartment.
Valve spring free length should be checked and installed
so the dampening coils are located opposite the keepers.
INSTALL PIN Release valve spring tension to lock
cap in place.
FOR 8 HP AND LARGER (EXCEPT VALVE-IN-HEAD)
FREE
LENGTH
1.885"
(47.879 mm)
DAMPENING COILS ON VALVE SPRINGS. The valve
spring should be assembled so the dampening coil
is located to the stationary end of the spring (opposite
the cap and retainers).
VALVE-IN-HEAD SPRINGS. Check valve spring free
length, it should be 1-15/16'' (49.225 mm) long. If
both ends are not parallel, replace with new springs.
SPRING MUST BE SQUARE
FREE
LENGTH
1.938"
(49.225 MM)
FOR VALVE-IN-HEAD ENGINES
VALVE GRINDING. Valve grinding procedures are
the same for all 8 horsepower and other engines.
(Including overhead valve engines). See Chapter
on specifications.
Correct valve grinding procedures are essential to
obtain a satisfactory result.
Face and seat angles must be accurate and the surfaces
must be smooth.
A 1/32" (.787 mm) margin must be left on the valve
head after refacing. The valve without a margin would
burn and distort very rapidly.
Use a "Vee" block and the flat side of a grindstone
to grind valve clearance. The end of the stem must
be flat and true or abnormal wear will occur.
SPRING MUST BE SQUARE
DAMPENING COILS
LOCATED CLOSER
TOGETHER
DAMPENING COILS
LOCATED CLOSER
TOGETHER.
POSITION TOWARD
VALVE BOX.
MARGIN
45°
MUST BE FLAT
STEM
AND TRUE
OVERSIZE STEM
DIAMETER
SEE SPECIFICATIONS
WRONG
IMPORTANT: GRIND FLAT TO OBTAIN
CORRECT VALVE CLEARANCE
VALVE SEATS. Valve seats are not replaceable. If
they are burned or pitted, they can be recut using a
Neway valve and seat cutter. Seats are cut to an
angle of 46°. If the seat is over 3/64'' (1.194 mm)
wide after cutting, use a 30° cutter to narrow the
face.
46° ANGLE
VALVE SEAT IN CYLINDER
VALVE SEAT CUTTING REQUIREMENTS. Cut valve
seats to 46° and valve to 45°. See Specifications.
VALVE SEAT 46°
EXHAUST
VALVE SEAT IN HEAD
VALVE GUIDE DIMENSIONAL CHECK. Check
dimensions per specification requirements, determine
if valve guide clearance is beyond acceptable tolerance.
If valve guide clearance is worn beyond tolerance,
ream valve guide oversize and install 1/32'' (.787
mm) oversize valve, or replace valve guides.
NO MARGIN
1/32"
(.787 mm)
FACE
WRONG
STANDARD STEM
DIAMETER
SEE SPECIFICATIONS
MUST BE FLAT
AND TRUE
ALWAYS DEGLAZE
CYLINDER WALL
SEE SPECIFICATIONS
SECTION FOR
DIMENSIONS
INTAKE
29