Tecumseh ECV100-120 - TECHNICIAN S Handbook page 90

Valve Seats
Valve seats are not replaceable. If they are burned, pitted, or distorted they can be reground using a grinding stone or
a valve seat cutting tool. Valve seats are ground to an angle of 46 degrees. Check the specifications section for proper
width.
The recommended procedure to properly cut a valve seat is to use the Neway Valve Cutting System, which consists
of three different cutters. LEV engines have a small combustion chamber and require the use of a special Neway
cutter #103 for the 46 and 31 degree combination cutter. The 60 degree cutter is Neway cutter #101. The tapered
pilots required are; Neway #100-1/4-1 for the .249 (6.325 mm) exhaust guide, and Neway #100-1/4 for the .250
(6.35 mm) intake guide. Consult the cutter's complete procedure guide for additional information.
NOTE: The valve seats are cast into the engine block at a slight angle on the LEV engines. When reconditioning valve
seats on the LEV engine, the seat cutter will make simultaneous contact with the seat and the aluminum portion of the
engine block. There is no detrimental effect to performance or life of the valve seat or block from the procedure.
First, use the 60 degree cutter to clean and narrow the seat from the bottom to the center (diag. 43).
Second, use the 31 degree cutter to clean and narrow the seat from the top toward the center (diag. 44).
Third or last, use the 46 degree cutter to cut the seat to a width of 3/64" (1.191 mm) (diag. 45).
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Valve Lifters
The valve lifters on some engines are different lengths. The shorter lifter is installed in the intake position and the
longer lifter is installed in the exhaust position. When removing, mark the lifters to install the lifter in the same position
as it was removed from.
Oversize Valve Guides
The valve guides are permanently installed in the cylinder block. If they get worn excessively, they can be reamed
oversize to accommodate a 1/32" (.793 mm) oversize valve stem.
The guides should be reamed oversize with a straight shanked hand reamer or low speed drill press. Refer to the
"Table of Specifications" (Chapter 10) to determine the correct oversize dimension. Reamers are available through
your local Tecumseh parts supplier. Consult the tool section in Chapter 11 for the correct part numbers.
The upper and lower valve spring caps must be redrilled to accommodate the oversize valve stems.
After oversizing the valve guides, the valve seats must be recut to align the valve seat to the valve guide.
CRANKCASE BREATHERS
The breather element and case can be cleaned using
cleaning solvent. Make sure the small drain hole or holes
are clean and installed facing down, so as to allow oil to
return back into the crankcase.
Top Mounted Breather
This type of breather is mounted in the top and rear of
the cylinder block in vertical shaft engines. The check
valve allows positive pressure to be vented through the
element and out the tube. Some engines have the
breather tube connected to the air cleaner assembly (diag.
46).
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