Service Manual
Assembly
Clean
off
any carbon on the valve stem and valve
guide hole. Apply engine oil to the valve and valve
guide. Assemble in reverse of disassembly proce-
dures.
Valve
Spring:
Check valve springs for cracks, worn ends, distor-
tion, and tension.
If
spring ends are worn, check
valve spring retainer for wear. Check for spring dis-
tortion by placing the spring on a flat surface next to
a square. Measure height of spring (A) and rotate it
against square edge to measure distortion (B), see
Figure
11-7.
If
distortion exceeds
0.06
inch
(1.5
mm) replace the spring. Check spring tension
at the valve open position using an accurate valve
spring tester. Replace any valve spring that
is
weak,
cracked, worn, or distorted.
FIGURE
11-7.
MEASURING VALVE
SPRING
Valve
Face
and
Seat
Grinding
Before installing new or used valves, inspect the
valve seats for proper valve seating.
If
used valves
are
reinstalled, the valve stems should be cleaned
and valve faces ground to their specified angles of
45F
Refinish valve
seats
to a
45"
angle. When
refacing valves and seats, remove all evidence of
pitting and grooving.
If
the end
of
the valve stem
is
pitted or
worn,
true
it
and clean
it
up on the refacer
11-6
wheel.
A
very light grind is usually enough to square
the stem and remove any pits or burrs. The valve
guide should be thoroughly cleaned.
If
the valve
guide is worn, or the valve is warped, the necessary
parts must be replaced.
Refinish valve faces to
a
45"
angle on a valve refac-
ing machine. The first cut from valve face must be a
light grinding. Check
if
there is an unevenness of
metal being removed.
If
only part
of
valve's face has
been touched, check to see
if
the valve is properly
seated in the machine or
if
the valve is warped,
worn, or distorted. When cut is even around the
whole valve face, keep grinding until the complete
face is ground clean. Be sure the correct valve face
angle is maintained. When the valve head is
warped, a knife edge will
be
ground (Figure
11-8)
on
part or all of the head due to the large amount of
metal that must be removed to completely reface
the valve. 'Heavy valve heads are required for
strength and
good
heat dissipation. Knife edges
lead to breakage, burning, and pre-ignition due to
heat localizing on the edge.
Replace any valve that cannot be entirely refaced
while keeping a good valve margin (Figure
11-8)
or
is warped, worn, or damaged in any way. The
amount of grinding necessary to true a valve indi-
cates whether the valve head is worn or warped.
WARPED
VALVE
WITH
KNIFE
EDGE
KNIFE
EDGE
GOOD
MARGIN
FIGURE
11-8.
VALVE
HEAD
MARGIN