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REPLACE
VALVE STEM SHIELDS
OR
VALVE
SPRINGS
(CYLINDER
HEAD NOT
REMOVED)
(1) Set engine basic t i m i n g to T D C and remove A i r
Cleaner.
(2) Remove cylinder head covers and spark plugs.
(3) Remove coil w i r e from d i s t r i b u t o r and secure to
good ground to prevent engine f r o m s t a r t i n g .
(4) U s i n g suitable socket and flex handle at crank-
shaft pulley r e t a i n i n g bolt, t u r n engine so the # 1
piston is at Top Dead Center on the compression
stroke.
(5) Remove rocker arms w i t h rocker shaft and i n -
s t a l l a d u m m y shaft. The rocker arms should not be
disturbed and left on shaft.
(6) W i t h a i r hose attached to adapter tool C-3907
installed i n # 1 spark p l u g hole, apply 620.5 to 689
k P a (90 to 100 psi) a i r pressure.
(7) U s i n g Tool C-3906 or C-4228 compress valve
s p r i n g and remove retainer valve locks and valve
spring.
(8) I n s t a l l seals on the exhaust valve stem and po-
s i t i o n down against valve guides.
(9) The i n t a k e valve stem seals should be pushed
f i r m l y and squarely over the valve guide using the
valve stem as a guide. DO N O T FORCE seal against
top of guide. W h e n
i n s t a l l i n g the valve retainer
locks, compress the s p r i n g only enough to i n s t a l l the
locks.
(10) Follow the same procedure on the r e m a i n i n g 5
cylinders using the f i r i n g sequence 1-6-5-4-3-2. M a k e
sure piston i n cylinder is at T D C on the valve spring
t h a t is being removed.
(11) Remove adapter Tool 3907.
(12) Remove d u m m y shaft a n d i n s t a l l rocker shaft
w i t h rocker arms.
(13) I n s t a l l covers and coil w i r e to distributor.
(14) I n s t a l l air cleaner.
(15) Road test vehicle.
HYDRAULIC TAPPETS
V a l v e t r a i n modifications include roller tappet as-
semblies, a l i g n i n g yokes and yoke retainers.
Roller tappet a l i g n m e n t is m a i n t a i n e d by machined
flats
on tappet body being f i t t e d ( i n pairs)into six
a l i g n i n g yokes. The yokes are secured by an align-
m e n t yoke retainer (Fig. 1).
Before disassembling any p a r t of the engine to cor-
rect tappet noise, read the o i l pressure at the gauge
(install a reliable gauge at pressure sending u n i t ) .
The pressure should be between 207 to 552 kPa (30
and 80 psi) at 2000 R.P.M. I f vehicle has no o i l pres-
sure gauge, check t h e oil level i n the o i l pan.
The oil level i n t h e pan should never be above the
F U L L
m a r k on dipstick, or below the A D D
O I L
m a r k . E i t h e r of these two conditions could be respon-
sible for noisy tappets. Check t h e o i l level after the
Fig. 1 Roller Tappets Aligning Yoke and Retainer
engine reaches n o r m a l operating temperature. A l l o w
5 m i n u t e s to stabilize o i l level, check dipstick.
OIL LEVEL
TOO
HIGH
I f o i l level is above the F U L L m a r k on dipstick, i t
is possible for the connecting rods to dip i n t o t h e o i l
w h i l e engine is r u n n i n g and create foam. Foam i n o i l
pan w o u l d be fed to t h e h y d r a u l i c tappets by t h e o i l
p u m p causing t h e m to lose l e n g t h and allow valves
to seat n o i s i l y .
OIL LEVEL
TOO
LOW
Low o i l level m a y allow o i l p u m p to take i n a i r
w h i c h w h e n fed to t h e tappets, causes t h e m to lose
l e n g t h a n d allows valves to seat noisily. A n y leaks
on i n t a k e side of o i l p u m p t h r o u g h w h i c h a i r can be
d r a w n w i l l create t h e same tappet action. Check t h e
l u b r i c a t i o n system f r o m the i n t a k e strainer to t h e
p u m p cover, i n c l u d i n g the r e l i e f valve retainer cap.
W h e n tappet noise is due to aeration, i t may be i n -
t e r m i t t e n t or constant, and u s u a l l y more t h a n one
tappet w i l l be noisy. W h e n o i l level and leaks have
been corrected, engine should be operated at fast idle
for sufficient t i m e to allow a l l of the air inside of t h e
tappets to be bled out.
TAPPET
NOISE
DIAGNOSIS
(1) To determine source of tappet noise,operate en-
gine at idle w i t h cylinder head covers removed.
(2) Feel each valve s p r i n g or rocker a r m to detect
noisy tappet. The noisy tappet w i l l cause the affected
spring and/or rocker a r m to v i b r a t e or feel r o u g h i n
operation.
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