ENGINE
TUNE-UP
6C-5
adjustment on the vehicle. Whenever possible, a
dwell
meter should be used for better accuracy.
V-8
1. With engine running at Idle, raise the adjusting
screw
window and insert an Allen wrench in the
socket of the adjusting screw.
2.
With dwell meter connected, adjust dwell angle
to 30
degrees
for all V-8 engines. A
2-degree
varia-
tion is allowable for wear. If a dwell meter is not
available,
turn adjusting screw clockwise until en-
gine
starts to misfire, then turn screw one-half turn
in
the
opposite
direction to complete adjustment.
3.
Close access cover fully to prevent the entry of
dirt
into the distributor.
6
CYL
On
6 cyl., adjust point gap with a flat feeler
gauge
to .019" (new) or .016" (used).
TEST
IGNITION
TIMING
AND ADVANCE
1. Attach a timing light and tachometer as shown
in
Fig. 6C-1.
NOTE:
Disconnect
both
hoses
from
dual
acting
vacuum
control
unit.
2. Set parking brake, start engine and run at slow
idle speed (solenoid inactive).
3.
Aim timing light at marks on lower timing
chain
cover and harmonic balancer.
4. Adjust timing as required by loosening clamp
bolt and rotating distributor until correct timing is
indicated,
then tighten clamp bolt.
5. Disconnect timing light.
6. Reconnect distributor spark advance and retard
hoses, then perform idle speed and mixture adjust-
ment. (See Section 6D)
6 Cyl. 4 Bbl.
5°BTDC
6 Cyl. 1 Bbl.
0°TDC
V-8
(All)
9°BTDC
IDLE
SPEED
AND
MIXTURE
1. Connect tachometer to engine. Set parking
brake.
Start engine, allow to idle.
2. With a thoroughly warmed-up engine, check to
see that choke is fully open and carburetor is on slow
idle.
3.
Adjust idle speed and mixture screws to
give
proper
idle speed.
NOTE:
Depress
or
plug
hot
idle
compensator
valve
while
adjusting
all
engines
so
equipped
(6
cyl.
1 bbl.
with
A/C and 6 cyl. 4 bbl.
only.)
Follow
procedures outlined in
EXHAUST
EMIS-
SIONS
SECTION
and adjust idle
speeds
to
settings
given at end of that section.
POSITIVE
CRANKCASE
VENTILATION
All
1968
engines
have the closed positive ventila-
tion systems utilizing manifold vacuum to draw
fumes and contaminating vapors into the combustion
chamber
where they are burned. The crankcase
ventilation system has an important function and
should be understood and serviced properly.
In
the closed crankcase ventilation system, air is
drawn
through the engine, through a regulating valve
and
into the manifold, drawing crankcase vapors and
fumes with it to be burned. The closed positive
ventilation system draws the clean air from the
carburetor
air cleaner and has a nonvented oil filler
cap.
The
P.C.V.
valves are designed specifically for
each engine to control the amount of flow from the
crankcase
to manifold.
VALVES
SHOULD
NEVER
BE
INTERCHANGED
BETWEEN
6 AND 8
CYLINDER
ENGINES.
The
crankcase ventilation valve should be checked
at regular intervals otherwise it
will
become
plugged
and
ineffective.
The
P.C.V.
system should be serviced as follows:
1. Disconnect all
hoses
and blow them out with
compressed air. If any
hose
cannot be freed of
obstructions, replace with new hose.
2. Remove crankcase ventilation valve assembly
from
rubber grommet, and discard.
3.
Clean
crankcase and intake manifold connec-
tors; using care not to allow dirt to enter openings.
4.
Clean
and re-oil ventilation filter in air cleaner.
5. Reinstall
Crankcase
Ventilation System, using a
new
P.C.V.
valve.
6. Adjust carburetor idle to specifications, sec-
tion 6D.
ROAD
TEST
TEST
PERFORMANCE
OF CAR
Observe
performance of engine at low speed, dur-
ing acceleration, and at constant speed.
Check
for
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