3-30 ENGINE
TOP
NARROWING CUT
•
If the contact area is too high on the valve,
or if
it is too wide,
use the 15° cutter to lower and narrow the contact area.
FINAL
SEAT
CUT
•
If the contact area is too low or too narrow, use the 45° cutter
to
raise and widen the contact area. If the contact area is too
high
or
too wide, use the
15°
cutter to lower and narrow
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
previous cutting operations.
A CAUTION
DO NOT use a 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 fin-
ish.
This
will
provide a soft surface for the final seat-
ing 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
clearance
after the cylinder head has
been
installed. (CZr* 2-5)
Contact area too high and
too
wide on face of valve
I
©^
Contact area too low and
too
narrow on face of valve