Chevrolet 70 Series 1970, Service Manual

Page: 520 / 841

ENGINE FUEL SYSTEM 6M-27
Figure 16—Removing Injector from C ylinder Head
INJECTOR INSTALLATION
NOTE: R efe r to "Engine M aintenance and
Tune-up" in Section 6C of th is manual.
B efore in stallin g an in je c to r in an engine, r e ­
move the carbon d eposits from the beveled se a t of
the in jecto r tube in the cylinder head. T his will
a s s u r e c o r re c t alignm ent of the in jecto r and p r e ­
vent any undue s tr e s s e s fro m being ex erted ag ainst
the sp ra y tip.
Use in jecto r tube bevel re a m e r J-5 2 8 9 -9 , to
clean the carbon fro m the in jecto r tube. E x ercise
c a re to rem ove ONLY the carbon so that the p ro p e r
cle a ra n c e betw een the in jecto r body and the cylin­
d e r head is m aintained. P ack the flutes of the re a m ­
e r with g re a s e to re ta in the carbon rem oved from
the tube.
In stall the in je c to r in the engine a s follows:
1. R efe r to fig u re 15 and in s e rt the in jecto r
into the in je c to r tube. Be s u re the dowel pin in the
in je c to r body re g is te r s w ith the dowel pin hole in
th e head. Next, position the in jecto r ra c k control
le v e r so the low er end of the le v e r engages the in­
je c to r ra ck .
2. In stall the in je c to r clam p, special w asher,
and nut. Tighten the nut to 20 to 25 foot-pounds
to rq u e. Then, check to m ake s u re the clam p does
not in te rfe re with the in je c to r follow er sp rin g o r
the exhaust valve sp rin g s.
NOTE: Check the in je c to r ra c k for fre e m ove­
m ent. E x cess torque can cause the in je c to r control
ra c k to s tic k o r bind.
3. Move the ro c k e r a rm assem b ly into p o s i­
tion and tighten the ro c k e r a rm b ra ck et b olts to
50 to 55 foot-pounds torque on 53 S e rie s and 90 to
100 foot-pounds to rq u e on 71 S e rie s.
IMPORTANT: On fo ur-v alv e cylinder heads,
th e re is a p o ssib ility of dam aging the exhaust
valves if the exhaust valve bridg e is not re stin g
on the ends of the exhaust valves when tightening
th e ro c k e r shaft b ra c k e t b olts. T h erefo re, note the
position of the exhaust valve b rid g e before, during,
and a fte r tightening the ro c k e r shaft b ra ck et b olts.
4. Rem ove th e shipping cap s. Then align the
fuel lin es and connect them to the in je c to r and the
fuel connectors. Use socket (J-8932-01) and a
to rq u e w rench to tighten the connections to 12 to
15 foot-pounds to rq u e.
CAUTION: DO NOT exceed the speci­
fied torque. Excessive tightening will
twist or fracture the flared end of the
fuel line and result in leaks. Lubricating
oil diluted by fuel oil can cause serious
damage to the engine bearings.
5. A fter in stallin g injector(s) in the engine,
p e rfo rm a com plete engine tune-up a s outlined in
Section 6C of th is m anual. However, if only one
in je c to r has been rep laced , and the o th er in je c to rs
and governor adju stm ent has not been disturbed,
it w ill be n e c e s s a ry to adjust the valve cle a ra n c e
and tim e the in jecto r, also to position the in jecto r
ra c k con tro l le v e r only on the in jecto r which has
been rep laced , except the num ber one cylinder. If
the num ber one in je c to r (which is the in jecto r se t
to governor) is rem oved it w ill be n e c e s s a ry to
loosen a ll in je c to r ra c k s c re w s and r e s e t the con­
tro l ra c k a s d esc rib ed in Section 6C of th is m anual
under "Engine M aintenance and T une-up."
INJECTOR TESTING
If inspection does not re v e a l any ex tern al dam ­
age, then a s e r ie s of te s ts should be m ade to de­
te rm in e the condition of the in je c to r to avoid un­
n e c e ss a ry overhauling.
An in jecto r th at p a s s e s a ll of the te s ts outlined
following may be con sid ered to be sa tisfa c to ry fo r
s e rv ic e , o th er than the visual check of th ep lu n g er.
However, an in jecto r that fa ils to p a s s one o r m ore
of th e te s ts is u n satisfac to ry and the fa u lts should
be c o rre c te d .
In jecto r C ontrol R ack and P lun ger
Movement T est
Check to se e if the plunger w orks freely in its
bushing and w hether the control ra c k m oves back
and fo rth fre e ly .
P lac e the inj ec to r in the in j ecto r te s te r (J - 9787)
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL