Chevrolet BEAUVILLE SPORTVAN G10 SERIES, Service Manual

Page: 160 / 350

ENG IN E 6-31
a. C rank engine until m ark on torsional dam per lines
up w ith cen ter o r “ O ” m ark on the tim ing tab
fastened to th e crankcase fro n t cover an d the engine
is in th e n um ber 1 firing position. This m ay be
determ in ed b y placing fingers o n th e num ber
1
valve as th e m ark on th e dam per com es near the
“ O ” m ark o n th e crankcase fro n t cover. I f the
valves are n o t m oving, th e engine is in th e n um ber
1
firing position. I f th e valves move as th e m ark
com es up to th e tim ing ta b , th e engine is in num ber
6
firing positio n and sh o u ld be tu rn e d over one
m ore tim e to reach the n u m b er
1
position.
b. W ith th e engine in th e n u m b er 1 firing position as
determ ined above, th e follow ing valves m ay be
adjusted.
E xhaust — 1 , 3 , 4 ,
8
In tak e — 1, 2, 5, 7
c. Back o u t adjusting n u t u n til lash is felt a t the push
ro d th e n tu rn in adjusting n u t until all lash is
rem oved. This can be d eterm ined b y checking push
ro d side play while tu rn in g adjusting n u t (Fig.
8
V).
W hen play has been rem oved, tu rn adjusting n u t in
one full ad ditional tu rn (to cen ter lifter plunger).
d. C rank th e engine one revolution u n til th e poin ter
“ O ” m ark and torsional dam per m ark are again in
alignm ent. This is n u m b er
6
firing position. W ith
th e engine in this p o sitio n the follow ing valves m ay
be adjusted.
E xhaust — 2, 5,
6
, 7
In tak e - 3 , 4 ,
6 ,8
4. Install rocker arm covers as outlined.
5. A djust carb u re to r idle speed.
V A L V E LIFTERS
H ydraulic valve lifters very seldom require a tte n tio n . The
lifters are extrem ely sim ple in design, readjustm ents are n o t
necessary, and servicing o f th e lifters requires only th a t care
and cleanliness be exercised in th e handling o f parts.
Locating Noisy Lifters
L ocate a noisy valve lifte r b y using a piece o f garden hose
appro x im ately fo u r feet in length. Place one end o f the hose
near th e end o f each intake an d exhaust valve w ith th e o ther
en d o f th e hose to th e ear. In this m anner, th e sound is
localized m aking i t easy to determ ine w hich lifter is a t fault.
A n o th er m e th o d is to place a finger on th e face o f th e valve
spring retainer. I f th e lifter is n o t functio n in g pro p erly , a
d istinct shock will be fe lt w hen the valve re tu rn s to its seat.
The general types o f valve lifte r noise are as follows:
1. H ard R apping N oise—Usually caused by th e plunger
becom ing tig h t in th e b ore o f th e lifter b o d y to such an
e x te n t th a t th e re tu rn spring can n o longer push th e
plunger back up to w orking position. Probable causes
are:
a. E x c e s s iv e varnish or carbon deposit causing
abnorm al stickiness.
b. Galling or “ pick-up” betw een plunger an d bore o f
lifter b o d y , usually caused b y an abrasive piece o f
d irt o r m etal wedging b etw een plunger an d lifter
b ody.
2. M oderate R apping Noise—Probable causes are:
a. Excessively high leakdow n rate.
b. Leaky check valve seat.
c. Im proper adjustm ent,
3. G eneral Noise T h ro u g h o u t th e Valve T rain—This w ill, in
m ost cases, be caused b y either insufficient oil supply or
im proper adjustm ent.
4. I n te rm itte n t C lick in g -P ro b ab le causes are:
a. A m icroscopic piece o f d irt m om entarily caught
betw een ball seat an d check valve ball.
b. In rare cases, the ball itself m ay be o ut-of-round or
have a flat spot.
c. Im p ro p er adjustm ent.
In m ost cases w here noise exists in one or m ore lifters all
lifter units should be rem oved, disassem bled, cleaned in a
solvent, reassem bled, and reinstalled in th e engine. I f dirt,
corrosion, carb o n , etc. is show n to exist in one u n it, it m ore
likely exists in all th e units, th u s it w ould only be a m a tte r o f
tim e before all lifters caused trouble.
Removal
1. Rem ove intake m anifold as outlined.
2. Rem ove valve m echanism as outlined.
3. Rem ove valve lifters.
N O T E : Place valve lifters in a rack so they may be
reinstalled in the same location.
Installation
1. Install valve lifters.
2. Install intake m anifold as outlined.
3. Install and adjust valve m echanism as outlined.
V A L V E STEM O IL SEAL and/or V A L V E SPRING
Replacement
1. Rem ove rocker arm cover as o utlined.
2. Rem ove spark plug, ro ck e r arm and push ro d on the
cylinder(s) to be serviced.
3. In sta ll a ir lin e a d a p te r T o o l J - 2 3 5 9 0 to s p a rk p lu g
p o r t a n d a p p ly c o m p re sse d a ir to th e s p a rk p lu g h o le
to h o ld th e valv es in p la ce .
4. Using Tool J-5892 to com press th e valve spring, rem ove
th e valve locks, valve cap and valve spring an d dam per
(Fig. 9V).
5. Rem ove th e valve stem oil seal.
6
. Assemble as follow s:
a. S et th e valve spring and dam per, valve shield and
valve cap in place. The closely coiled end o f the
spring is installed against th e cylinder head.
Com press th e spring w ith T ool J-5892 an d install oil
seal in th e low er groove o f th e stem , m aking sure
th e seal is flat an d n o t tw isted.
N O T E : A light coat o f oil on the seal w ill help
prevent twisting.
b. Install th e valve locks an d release the com pressor
to o l m aking sure th e locks seat p roperly in th e
u p p er groove o f th e valve stem .
C H E V Y V A N S H O P M A N U A L