3-30 ENGINE
BOTTOM NARROWING CUT
• If the contact area W is too wide or too low, use the 60° (intake
side only) to narrow and raise the contact area.
FINAL SEAT CUT
• If the contact area W is too low or too narrow, use the 45° cutter
to raise and widen the contact area.
NOTE:
After cutting the 15°, 30° and 60° angles, it is possible that the
valve seat (45°) is too narrow. If so, re-cut the valve seat to the
correct width.
• After the desired seat position and width is achieved, use the
45° cutter very lightly to clean up any burrs caused by the pre-
vious cutting operations.
&
Do not use lapping compound after the final cut is made.
The finished valve seat should have a velvety smooth
finish but not a highly polished or shiny finish. This will
provide a soft surface for the final seating of the valve
which will occur during the first few seconds of engine
operation.
NOTE:
After servicing the valve seats, be sure to check the valve clear-
ance after the cylinder head has been reinstalled. (
!
2-6)
• Clean and assemble the head and valve components. Fill the
intake and exhaust ports with gasoline to check for leaks.
• If any leaks occur, inspect the valve seat and face for burrs or
other things that could prevent the valve from sealing.
)
Always use extreme caution when handling gasoline.
Contact area too low and too
narrow on face of valve
60˚
(Intake only)
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