Buick LeSabre 1965 Service Manual page 52

2 - 3 0 HEADS AND VALVES ENGINE
DRIVE OLD GUIDE OUT
FROM COMBUSTION
CHAMBER SIDE
DRIVE NEW GUIDE IN
FROM TOP SIDE OF HEAD
Figure 2-22—Removing and Installing Valve Guide
guides out from c o m b u s t i o n
chamber side using Driver J-269.
(b) Place cylinder head on hold-
ing fixture with valve cover studs
straight up, remove cover gasket
and clean gasket surface of head.
(c) Place Valve Guide Aligner
J-5240-2 over guide hole in head,
insert the valve guide either end
down, and use Installer J-5240-1
and hammer to drive guide down
into head until the shoulder on
the installer contacts top of the
aligner. See Figure 2-22. Repeat
for each guide.
(d) Use Valve Guide Reamer
J-129-3 to finish ream inlet and
exhaust guides. R e p l a c e m e n t
guides are not finish reamed to
size.
NOTE: On 300 engines with ex-
cessive clearance, ream out guide
.004", and install .004" oversize
valves available through the
parts department. Use Reamer
J-5830-1.
6. Reface valves and true up
valve seats to 45 degrees. Cutting
a valve seat results in lowering
the valve spring pressure and in-
creases the width of the seat. The
nominal width of a valve seat is
3/64" to 5/64" (1/16" average).
If valve seac is over 5/64" after
truing up, it should be narrowed
to specified width by using the
proper 20 degree and 70 degree
cutters.
Improper hydraulic valve lifter
operation may result if valve and
seat have been refinished enough
to allow the end of valve stem to
raise approximately .050" above
normal position. In this case it
will be necessary to grind off
end of valve stem or replace
parts.
The normal height of the valve
stem above the valve rocker arm
cover gasket surface of the cyl-
inder head is 1.540.
7. Lightly lap valves into seats
with fine grinding compound. The
refacing and reseating operations
should leave the refinished sur-
faces smooth and true so that a
minimum of lapping is required.
Excessive lapping will groove the
valve face and a grooved valve
will not seat tightly when hot.
8. Test valves for concentricity
with seats and for tight seating.
Valves usually are t e s t e d by
lightly coating the valve face with
Prussian blue and turning the
valve against its seat. This in-
dicates whether the seat is con-
centric with the valve guide but
does not prove that valve face is
concentric with the valve stem,
or that the valve is seating all
the way around. After making this
test, wash all blue from surfaces,
lightly coat valve seat with blue
and repeat the test to see whether
a full mark is obtained on the
valve. Both tests are necessary
to prove that a proper seat is
being obtained.
9. Reinstall center crossbar in
holding fixture, install valves in
guides, then install valve springs,
caps and keys. Place ends of
springs h a v i n g c l o s e d coils
against cylinder head.
c. Replacement of
Rocker Arms
(401 & 425 cu. in. Engines)
1. Remove cotter pin, flat washer
and spring washer from each end
of the rocker a r m shaft and
remove bolts from brackets. Re-
move rocker arms, brackets and
springs from shaft.
2. Clean and inspect all parts and
replace those that are excessively
worn.
3. A s s e m b l e springs, rocker
arms and brackets on shaft as
shown in Figure 2-23. Note that
the long spring is at middle of
shaft, the valve ends of all rocker
arms s l a n t toward middle of
PLAIN WASHER
SPRING
WASHER
Figure 2-23—Rocker Arm and Shaft
Assembly