Chevrolet CHEVY VAN G10 SERIES Service Manual page 176

ENGINE FUEL 6M-2
1. Thoroughly w arm -up engine. If th e engine is cold, allow
to run for at least 15 m inutes.
2. Inspect to rq u e o f carbureto r to intake m anifold bolts and
intake m anifold to cylinder head bolts to exclude the
possibility o f air leaks.
3. Inspect m anifold heat contro l valve (if used) for freedom
o f action and correct spring tension.
ROCHESTER AAV, 2GV AND 4M ADJUSTMENTS
F A S T I D L E A D JU S T M E N T S (F IG S . IC , 2 C A N D 3 C )
R O C H E S T E R M V A N D 4 M V
N O T E : The fast idle adjustment must be set w ith
transmission in "N e u tra l."
1. Position fast idle lever on high step o f fast idle cam.
(Second step on 4MV)
2. Be sure choke is properly adjusted and in wide open
position — engine warm.
3. Set fast idle to specified rpm as follows:
a. A djust fast idle screw on R ochester 4MV (Fig. 2C).
b. Bend fast idle lever as required on R ochester MV to
specified speed (Fig. 1C).
Manual Choke
1. Use same procedure as above except in S tep 1 ro tate the
fast idle cam clockwise to its highest position.
CHOKE ROD (FAST IDLE CAM) ADJUSTMENTS
MV (Fig. 4C)
A utom atic choke m odels w ith steps on fast idle cam. With
fast idle adjustm ent m ade:
INSERT SCREWDRIVER IN
SLOT IN CAM FOLLOWER
BEND FOLLOWER IN OR
OUT TO ADJUST
HOLD LEVER AT
THIS POINT WITH
TOOL OR PLIERS
FAST IDLE CAM STEPS
FAST IDLE ADJUSTMENT
Fig. 1C —Fast Idle Adjustm ent (Rochester M V )
PRELIMINARY CHECKS (ALL CARBURETORS)
EXTERNAL ADJUSTMENTS (ALL CARBURETORS)
CAM FOLLOWER ON
nnvi i u
SPECIFICATIONS
4. Check and adjust choke as required, using procedures
specified in this section.
5. A djust idle speed and idle m ixture as outlined in Section
6
, " Engine T une-up" and at the end of the carburetor
group in this section un d er, "A dditional E xternal S et­
tings and A djustm ents."
1. Place fast idle cam follow er on second step o f the fast
idle cam and hold firm ly against the rise to the high step.
2. R o tate ih o k e valve tow ard direction o f closed choke by
applying force to choke coil lever.
3. Bend choke rod at point show n to give specified opening
betw een the lower edge o f choke valve (at center of
valve) and inside air horn wall.
©
INSERT SCREW DRIVER
IN SLOT IN CAM FOLLOWER
LEVER. BEND LEVER
IN OR OUT TO ADJUST TO
SPECIFIED R.P.M.
HOLD LEVER
TOOL OR PLIERS WHEN
BENDING TO PREVENT
DISTORTION
Fig. 3C —Fast Idle Adjustm ent (Manual Choke)
ROTATE FAST IDLE CAM
CLOCKWISE TO
HIGHEST POSITION
SET CURB IDLE
R.P.M. TO
SPECIFICATIONS
C H E V Y V A N SH O P M A N U A L