Chevrolet 10 Series 1970 Service Manual page 339

the plunger back up to working position.
causes are:
a. E x c essive varnish o r carbon deposit causing ab­
norm al stickiness.
b. G alling o r " pickup" between plunger and b o re of
lifte r body, usually caused by an a brasive piece
of d irt o r m etal wedging between plunger and
lifte r body.
2. M oderate Rapping N oise - Probable causes are:
a. E x c e s s iv e ly high leakdown rate.
b. Leaky check va lve seat.
c. Im p rop er adjustment.
3. G en eral N o ise Throughout the V a lve T ra in - This
w ill, in alm ost a ll cases, be a definite indication of
insufficient o il supply, o r im p ro p er adjustment.
4. Interm ittent C licking - Prob ab le causes are:
a. A m ic ro scop ic p iece of d irt m om entarily caught
between b all seat and check va lve ball.
b. In ra re cases, the ball its e lf may be out-of-round
o r have a fla t spot.
c. Im p rop er adjustment.
In m ost cases, where noise exists in one o r m ore
lifte r s , a ll lift e r units should be rem oved, disassem bled,
cleaned in a solvent, reassem bled, and rein stalled in the
engine. If dirt, varnish, carbon, etc. is shown to exist in
one unit, it m ore than lik e ly exists in a ll the units, thus
it would only be a m atter of tim e b e fo re all lifte r s caused
trouble.
Removal
1. R em ove va lv e m echanism as outlined.
2. M ark distribu tor housing, with chalk, at number one
and number six cylin d er position (plug w ir e ) then
disconnect plug w ire s
rem ove d istrib u tor cap and plug w ire assem bly.
3. Crank engine until d istrib u tor ro to r points to number
one position, then disconnect distribu tor p rim a ry
lead at c o il and rem ove distributor.
4. R em ove push rod c o v e rs (d isca rd gaskets).
5. R em ove va lve lifte r s .
NOTE: P la c e v a lv e lifte r s
may be rein sta lled in the sam e location.
Installation
1. In sta ll va lv e lifte r s .
NOTE: W henever new va lve
installed, polish lift e r fe e t with #600 wet/dry
Fig . 2 L —A ir A d a p te r Tool
Probable
at spark plugs and c o il and
in a rack so they
lifte r s are being
e m ery paper and coat foot of v a lv e lifte r s with
"M o ly k o te " or its equivalent.
2. Install push rod co vers, using new gaskets,
torque to specification s.
3. Install distribu tor, positioning ro to r to number one
cylin der position, then connect p rim a ry lead at coil.
4. Install and adjust va lve
5. Adjust ignition tim ing and carb u retor idle speed and
m ixture.
V a lv e Stem O il Seal a n d /o r V a lv e Spring
Replacement
1. R em ove ro ck er arm co ve r as outlined.
2. R em ove spark plug, ro c k e r arm and push rod on the
cylin d e r(s ) to be s erviced .
3. Apply com pressed a ir to the spark plug hole to hold
the va lv es in place.
NOTE: A tool to apply a ir to the cylin d er is
available through lo c a l jobbers or m ay be manu­
factured. In manufacturing this to o l a AC -46N
spark plug o r its equivalent is recom m ended.
This w ill make the tool u n iversal fo r all C h evro­
let engines. C hisel the spark plug as shown, then
d rive the po rcela in out of the plug by tapping the
center ele ctrod e against a hard block. Using a
3/8" pipe tap, cut threads in the rem aining p o r­
tion of the spark plug and assem ble as shown
(fig . 2L).
4. Using T o o l J-5892 to com press the va lv e spring,
rem ove the v a lve locks, va lve cap (o r ro ta to r) va lve
shield and va lve sp rin g and damper (fig . 3L).
5. Rem ove the va lv e stem o il seal.
6. To replace, set the va lve spring and damper, va lve
sh ield and va lve cap (o r rota tor) in place. The close
co iled end of the spring is in stalled against the c y l­
inder head. C om press the spring with T o o l J-5892
■ \
F ig . 3 L—Compressing V a lv e Spring
ENGINE 6-17
and
m echanism as outlined.
CHEVROLET TRUCK SERVICE MANUAL