Chevrolet 70 Series 1970, Service Manual

Page: 420 / 841

53 AND 71 SERIES DIESEL ENGINES 6C-23
the speed control le v e r reach es the end
of its tra v el (stop under the governor
cover). T his w ill resu lt in a slight
step-up in effort required to m ove the
speed control le v e r to its maximum
speed p osition and a deflection in the
fuel rod (fuel rod deflection can be
se e n at the bend).
(4) If the rack is too tight, back off the inner
adjusting sc rew sligh tly and tighten the
outer adjusting scr ew .
NOTE: A fter the No. 1 on 6 -7 1 , or 1L and 1R
on V
8
engine, injector rack control le v e r is c o r ­
rectly se t, it must not be changed throughout the
adjustm ent of the rem aining injector rack control
le v e r s , sin c e it is se t to the governor.
g. On V
8
en gines, p osition the 1R cylinder as
d escrib ed in Steps e and f p reviou sly. Repeat the
check on 1L and 1R a s outlined in Step f.
NOTE: Both in jector control racks (lL a n d lR )
should be the sa m e.
h. With governor control le v e r held in "FULL-
FUEL" p osition, note rotary m ovem ent of No. 1 or
1L and 1R on V
8
engine in jector rack to lev er
coupling. P r e s s u r e of fin ger tip w ill produce a
tendency to rotate, but coupling should not be
lo o se . A ll rem aining in jector rack control le v e r s
m ust now be adjusted to the sam e "feel" at coup­
ling to ensure sam e amount of fuel injected into
each cylinder at "FULL-LOAD” a s follow s:
NOTE: On V
8
engines after 1L and 1R have
been s e t so they a re alike the rem ainder of in jec­
tor control racks on either cylinder head can be
adjusted from the front to the r e a r . On In -lin e en­
gine after No. 1 is p rop erly se t the rem aining can
be se t from front to r ea r.
i. Hold governor control le v e r in "FULL-
FUEL” p osition. Adjust No. 2 in jector rack control
le v e r 2L or 2R on V
8
engine by turning down inner
adjusting scre w until the injector rack has moved
to "FULL-FUEL" p osition . T his can be noticed as
the coupling pick s up. Turn the outer adjusting
sc r e w until it bottom s ligh tly on the injector con­
tr o l tube. Then alternately tighten both inner and
outer adjusting sc r e w s .
NOTE: When the se ttin g s a re co rrect the racks
of the in jectors must be snug and the sam e tension
on the ball end of th eir r e sp ec tiv e rack control
le v e r s when checked with screw d riv er o r fin g ers
(fig s. 12 and 13).
j. R echeck the No. 2 and No. 1 injector rack
couplings on In -lin e engine with screw d riv er or
fin ger tip to check rotary m ovem ent, or recheck
the 2L and 1L on V
8
engine.
k. If No. 1 in jector rack coupling now fe e ls
lo o se , No. 2 injector rack coupling is too tight.
C orrect No. 2 injector rack adjustment by lo o se n ­
ing inner adjusting sc r e w and tightening outer
adjusting scre w .
1. If No. 2 injector rack coupling fe e ls lo o se ,
c o r r e ct by loosening outer adjusting sc r e w sligh tly
and tighten inner adjusting screw .
m, When No. 2 injector rack coupling "feels"
the sam e a s No. 1, repeat th is procedure (opera­
tion s h, i, j, k, and
1
) on a ll rem aining injector
ra c k s. That is , com pare No. 3 injector rack coup­
lin g with No. 1, e tc ., until a ll control racks are
properly adjusted.
NOTE: An accurate rack settin g in "FULL-
FUEL" p osition w ill r esu lt in balanced injection
throughout the en tire operating range. T herefore,
a "rough" idle after tune-up c a lls for a check of
governor, in jectors and related con trols. Do not
attem pt to change rack position with engine idling
o r operating at any position with engine idling or
operating at any sp eed . When one rack is adjusted
"in" m ore than the o th ers, only that one in jector
rack can reach "FULL-FUEL" position. A s a r e ­
su lt, maximum output of the engine w ill be reduced.
n. On V
8
engines, turn the id le speed adjust­
ing sc r e w in until it p ro jects 3/16" from lock nut
to perm it starting engine (fig. 14).
0 . Connect throttle and stop linkage to gov­
ernor co v er, making su re it is properly adjusted
a s d escrib ed in ENGINE FUEL SYSTEM (
6
M) of
th is manual.
p. In stall rocker arm co v er and gasket.
ADJUST MAXIMUM NO-LOAD SPEED
A fter positioning the injector rack control
le v e r s , s e t the maximum engine speed a s follow s:
NOTE: B e su re the buffer sc r e w p ro jects 5/8"
from the lock nut to prevent in terferen ce w hile ad­
justing the maximum n o-load speed.
1. L oosen the high sp eed spring retain er lock
nut (fig. 15), using a spanner wrench.
2. With the engine running at operating tem p­
erature and no-load on the engine, p lace the speed
Figure 14—Idle Speed Adjustment (Typical)
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL