Valve Service; Valve Seats; Oversize Valve Guides; Valve Lifters - Tecumseh SPECTRA 37 Service And Repair Manual

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b) VALVE SERVICE
Clean all parts and remove carbon from valve heads and
stems. If valves are in usable condition, grind or cut the
valve faces to 45 degrees angle using tools 26990002
and 26990001. Replace valves if they are damaged,
distorted or if the margin is ground to less than 1/32" (0.8
mm) (Fig 74).

Valve seats

Valve seats are not replaceable. If they are burned or
pitted they can be reground using a grinding stone or
Neway Valve Reseater. Seats are ground at an angle of
46 degrees to a width of 3/64" (1.2 mm).
The recommended procedure to properly cut a valve seat
is to use the Neway Valve Cutting System, which consists
of different degree cutters. (88841013).
First use the 31 degree cutter to clean and narrow the
seat from the top toward the centre (Fig 75).
Second use the 46 degree cutter to cut in the seat to a
width of 3/64" (Fig 76).

Oversize valve guides

Valve guides are permanently installed in the head. If
they become worn excessively they can be reamed to
accommodate a 1/32" oversize valve stem.
You are recommended to bring guide diameter to 7 mm
and then ream with reamer 670283 (670328 for exhaust
valve guide). After oversizing the valve guide - the seats
must be re-cut to align with the valve guides.

Valve lifters

It is a good practice not to interchange lifters, even though
they are identical, once a wear pattern has been
established.
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Fig. 74
Fig. 75
Fig. 76
92