engine CHEVROLET CAMARO 1967 1.G Chassis Repair Manual
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Page 264 of 659
BRAKES
5-31
POWER BRAKES
INDEX
General Description 5-31
Maintenance
and"
Adjustments 5-31
Inspection . ... 5_31
Lubrication 5-31
Bleeding Instructions . . . 5.31
Air Cleaner Service . . . , 5.31
Page
Component Replacement 5-31
Power Brake Cylinder ......* 5-31
Removal . . 5-31
Disassembly and Assembly See Overhaul Manual
Installation . . . . 5-31
GENERAL DESCRIPTION
The Power Brake Unit is a self-contained hydraulic
and vacuum unit, utilizing manifold vacuum and atmos-
phere pressure for its power.
This unit permits the use of a low brake pedal as well
as less pedal effort than is required with the conventional
(nonpower) hydraulic brake system. Only two external
line connections are necessary -
one
a vacuum connection
from manifold to check valve located on front shell; the
other, a hydraulic connection from the main cylinder
outlet directly into the hydraulic system. The unit is
mounted on the engine side of the fire wall and directly
connected to the brake pedal.
MAINTENANCE AND ADJUSTMENTS
INSPECTIONS
1.
Check vacuum line and vacuum line connections as
well as vacuum check valve in front shell of power
unit for possible vacuum loss.
2.
Inspect all hydraulic lines and connections at the
wheel cylinders and main cylinder for possible
hydraulic leaks.
3.
Check brake assemblies for scored drums, grease
or brake fluid on linings, worn or glazed linings,
and make necessary adjustments.
4.
Check brake fluid level in the hydraulic reser-
voirs.
The reservoirs should be filled to the levels
shown in Figure 8.
5. Check for loose mounting bolts at main cylinder and
at power section.
6. Check air cleaner filter in power piston extension
and replace filter if necessary.
7. Check brake pedal for binding and misalignment
between pedal
-and
push rod.
LUBRICATION
The power brake unit is lubricated at assembly and
needs no further lubrication other than maintaining
normal reservoir fluid level. The reservoir should be
filled as described in this section.
BLEEDING INSTRUCTIONS
The power system may be bled manually or with a
pressure bleeder as outlined in this section. Use only
GM
Supreme 11 Brake Fluid or equivalent. Do not use the
power assist while bleeding. The engine should not be
running and the vacuum reserve should be reduced to
zero by applying the brake several times before starting
the bleeding procedure.
AIR CLEANER SERVICE
Servicing of the air cleaner is recommended and the
element replaced when restriction becomes severe
enough to affect power brake response. At any other
time, if cleaning of the filter is felt necessary, it should
be shaken free of dirt or washed in soap and water and
thoroughly dried.
COMPONENT REPLACEMENT
POWER BRAKE CYLINDER
Removal
1.
Remove vacuum hose from vacuum check valve.
2.
Disconnect hydraulic lines at main cylinder.
Disconnect push rod at brake pedal assembly.
Remove nuts and lock washers securing power unit
to fire wall, and remove power unit from engine
compartment.
3.
4.
NOTE:
Chevy
to fire wall.
has a three stud attachment
Repair procedures for the power cylinder are outlined
in the Brake Section of the Overhaul Manual-for service
of the main cylinder refer to applicable portion of
"Standard Brakes" in this manual.
Installation
1.
Mount the power brake assembly in place and install
the attaching nuts and lock washers.
2.
Attach vacuum line to check valve.
3.
Secure hydraulic lines to main cylinder.
4.
Attach push rod to brake pedal assembly, and check
operation of stop light.
5. Bleed brakes as outlined in this section.
CAUTION: After replacing the unit on the vehi-
cle,
start the engine and allow vacuum to build
up before applying the brake.
CHEVROLET CHASSIS SERVICE
Page 266 of 659
SECTION 6
ENGINE
CONTENTS
OF
THIS SECTION
Page
Engine Tune Up
6-1
Torque Sequence
Engine Mechanical
(In
Line)
6-12
Special Tools
. .
Engine Mechanical (V8)
6-24
Page
6-39
6-40
ENGINE TUNE UP
INDEX
Page
General Description
. 6-1
Mechanical Checks and Adjustments
6-1
Spark Plug Removal
6-1
Test Compression
6-1
Service and Install Spark Plugs
6-2
Service Ignition System
6-3
Service Battery
and
Battery Cables
6-5
Service Delcotron
and
Regulator
6-5
Service
Fan
Belt
6-5
Service Manifold Heat Valve
6-5
Tighten Manifold
6-5
Service Fuel Lines
and
Fuel Filter ..........
6-6
Service Cooling System
6-6
Check and Adjust Accelerator Linkage
6-6
Service Crankcase Ventilation
6-6
Service
Air
Injection Reactor System
6-6
Choke Adjustment
6-7
Page
Instrument Cheek-Out
6-7
Instrument Hook-Up.
. 6*7
Check and Adjust Dwell
6-7
Check Dwell Variation
6-7
Check and Adjust Timing
6-8
Adjust Idle Speed
and
Mixture
6-8
Additional Checks and Adjustments
. 6-8
Testing Crankcase Ventilation Valve
. 6-8
Testing Cranking Voltage
6-8
Cylinder Balance Test
. 6-8
Battery
6-8
Ignition
; 6-8
Carburetor
6-11
Fuel Pump
6-11
Cooling System
. 6-11
Cylinder Head Torque and Valve Adjustment
..... 6-11
GENERAL DESCRIPTION
The engine tune up
is
important
to the
modern automo-
tive engine with
its
vastly improved power and perform-
ance.
The
higher compression ratios, improved electri-
cal systems
and
other advances
in
design, make today1 s
engines more sensitive
and
have
a
decided effect
on
power, performance and fuel consumption.
It
is
seldom advisable
to
attempt
a
tune up
by
correc-
tion
of one or two
items only. Time will normally
be
saved
and
more lasting results assured
if the
technician
will follow
a
definite
and
thorough procedure
of
analysis
and correction
of all
items affecting power, performance
and economy.
The tune
up
will
be
performed
in
two parts.
The
first
part will consist
of
visual and mechanical checks and
ad-
justments;
the
second part will consist
of
an instrument
checkout that
can be
performed with
any one of the
units
of service equipment available
for
this purpose. Always
follow
the
instructions provided
by the
manufacturer
of
the particular equipment
to be
used.
Additional checks
and
adjustments
are
included
in the
latter part
of
this section
for use as
required. Many
of
these operations
can be
used
to
isolate and correct trou-
ble located during
the
tune up. Where conditions
are
UB-
covered requiring major corrective action, refer
to the
appropriate section
of
this manual
or the
Passenger
Chassis Overhaul Manual
for
detailed service informa-
tion.
Typical illustrations
and
procedures
are
used except
where specific illustrations
or
procedures
are
necessary
to clarify
the
operation. Illustrations showing bench
op-
erations
are
used
for
clarification however
all
operations
can
be
performed
on the
vehicle.
MECHANICAL CHECKS
AND
ADJUSTMENTS
Spark Plug Removal
Remove any foreign matter from around spark plugs
by
blowing
out
with compressed
air,
then disconnect wires
and remove plugs.
Test Compression
(Fig. 1)
The compression check
is
important because
an
engine
with
low or
uneven compression cannot
be
tuned success-
fully.
It is
essential that improper compression
be cor-
rected before proceeding with
the
engine tune
up.
1.
Remove
air
cleaner
and
block throttle
and
choke
in
wide open position.
2.
Hook
up
starter remote control cable
and
insert
compression gauge firmly
in
spark plug port.
CAUTION: Whenever
the
engine
is
cranked
CHEVROLET
C*
IS SERVICE MANUAL
Page 267 of 659
ENGINE 6-2
remotely at the starter, with a special jumper
cable or other means, the primary distributor
lead must be disconnected from the negative
post on the coil and the ignition switch must be
in the "ON" position. Failure to do this will
result in a damaged grounding circuit in the
ignition switch.
3.
Crank engine through at least four compression
strokes to obtain highest possible reading.
4.
Check and record compression of each cylinder.
5.
If one or more cylinders read low tor uneven, inject
about a tablespoon of engine oil on top of pistons
in low reading cylinders (through spark plug
port).
Crank engine several times and recheck
compression.
• If compression comes up but does not necessarily
reach normal, rings are worn.
• If compression does not improve, valves are
burnt, sticking or not seating properly.
• If two adjacent cylinders indicate low compres-
sion and injecting oil does not increase compres-
sion, the cause may be a head gasket leak between
the cylinders. Engine coolant and/or oil in cylin-
ders could result from this defect.
NOTE: If a weak cylinder cannot be located
with the compression check, see "Cylinder Bal-
ance Test" under "Additional Checks and Adjust-
ments" in this section.
Service and Install Spark Plugs (Fig. 2)
1.
Inspect each plug individually for badly worn elec-
trodes,
glazed, broken or blistered porcelains and
replace plugs where necessary. Refer to spark plug
diagnosis information presented in Section 6Y for an
analysis of plug conditions.
2.
Clean serviceable spark plugs thoroughly, using an
abrasive-type cleaner such as sand blast. File the
center electrode flat.
3.
Inspect each spark plug for make and heat range. All
plugs must be of the same make and number.
4.
Adjust spark plug gaps to specifications using a
round feeler gauge.
PORCELAIN
INSULATOR
INSULATOR CRACKS
OFTEN OCCUR HERE
CENTER ELECTRODE
[FILE FLAT WHEN
ADJUSTING GAP-
[DO NOT BEND!
(PROPER GAP)
(BEND TO ADJUST GAP)
CAUTION:
adjust gap.
Fig.
2 - Spark Plug Detail
Never bend the center electrode to
Always adjust by bending ground or
side electrode.
If available, test plugs with a spark plug tester.
Inspect spark plug hole threads and clean before in-
stalling plugs. Corrosion deposits can be removed
with a 14 mm. x 1.25 SAE spark plug tap (available
through local jobbers) or by using a small wire brush
in an electric drill. (Use grease on tap to catch
chips.)
ADJUST DWELL
ANGLE SETTING OR
POINT OPENING
Fig.
1 - Checking Compression
Fig.
3 - Distributor (In Line)
CHEVROLET CHASSIS SERVICE MANUAL
Page 268 of 659
ENGINE
6-3
(ROUND) Y~~fll^H
CENTRIFUGAL
A ^k
ADVANCE--jflgKpl
MECHANISM
UB|
CAM
KSK^2
LUBRICATOR
VlSMi
REPLACEMENT
^BK
-^ADJUST
SQUARELY
AND
JUST
TOUCHING
LOBE
OF
CAM
/ROTOR
HBB
__
I^BH^F
?
(SOUARE)
^K^ I /—
CAM
jKft^J / LUBRICATOR
H^T^
CAUTION!
QV NEVER
OIL
•L-^
CAM LUBRICATOR-
REPLACE
WICK
WHEN
NECESSARY
LATERAL
MISALIGNMENT
PROPER
LATERAL ALIGNMENT
Fig.
4- Distributor (V8)
CAUTION: Use extreme care
-when
using tap to
prevent cross threading. Also crank engine sev-
eral times to blow out any material dislodged
during cleaning operation.
7. Install spark plugs with new gaskets and torque to
specifications.
NOTE:
The following are some of the
greatest causes of unsatisfactory spark plug
performance.
•
Installation of plugs with insufficient torque to
fully seat the gasket.
•
Installation of the plugs using excessive torque
which changes gap settings.
•
Installation of plugs on dirty gasket seal.
•
Installation of plugs into corroded spark plug hole
threads.
8^ Connect spark plug wiring.
Service
Ignition System
1.
Remove distributor cap, clean cap and inspect for
cracks, carbon tracks and burned or corroded ter-
minals. Replace cap where necessary.
2.
Clean rotor and inspect for damage or deterioration.
Replace rotor where necessary.
3.
Replace brittle, oil soaked or damaged spark plug
wires.
Install all wires to proper spark plug. Proper
positioning of spark plug wires in supports is impor-
tant to prevent cross-firing.
4.
Tighten all ignition system connections.
5. Replace or repair any wires that are frayed, loose or
damaged.
Us
CORRECT
LATERAL MISALIGNMENT BY
j BENDING
FIXED CONTACT SUPPORT
[NEVER
BEND BREAKER LEVER
Fig.
5 - Point Alignment
Magnetic
Pulse(Breakerless)
Distributor
There are no moving parts in the ignition pulse ampli-
fier, and the distributor shaft and bushings have perma-
nent type lubrication, therefore no periodic maintenance
is required for the magnetic pulse ignition system. Refer
to Section 6Y for an analysis of problems and/or repair
procedures encountered on the Transistorized (Magnetic
Pulse) ignition system.
Standard
(Breaker Point) Distributor
(Figs.
3 or 4)
1.
Check the distributor centrifugal advance mechanism
by turning the distributor rotor in a clockwise direc-
tion as far as possible, then releasing the rotor to
see if the springs return it to its retarded position.
If the rotor does not return readily, the distributor
must be disassembled and the cause of the trouble
corrected.
2.
Check to see that the vacuum spark control operates
freely by turning the movable breaker plate counter-
clockwise to see if the spring returns to its retarded
position. Any stiffness in the operation of the spark
control will affect the ignition timing. Correct any
interference or binding condition noted.
3.
Examine distributor points and clean or replace if
riecessary.
DO
NOT SUCK
IN
TOO MUCH
ELECTROLYTE
TAKE
READING
AT
EYE LEVEL
Fig.
6 - Testing Specific Gravity of Battery
CHEVROtET
CHASSIS SERVICE MANUAL
Page 269 of 659
ENGINE 6-4
• Contact points with an overall gray color and only
slight roughness or pitting need not be replaced.
• Dirty points should be cleaned with a clean point
file.
Use only a few strokes of a clean, fine-cut con-
tact file. The file should not be used on other
metals and should not be allowed to become
greasy or dirty. Never use emery cloth or sand-
paper to clean contact points since particles will
embed and cause arcing and rapid burning of
points. Do not attempt to remove all roughness
nor dress the point surfaces down smooth.
Merely remove scale or dirt.
• Clean cam lobe with cleaning solvent, lubricate
cam lobe with "Delco Remy Cam and Ball Bearing
Lubricant" or its equivalent and rotate cam lubri-
cator wick 1/2 turn.
• Replace points that are burned or badly pitted.
NOTE: Where prematurely burned or badly
pitted points are encountered, the ignition sys-
tem and engine should be checked to determine
the cause of trouble so it can be eliminated.
Unless the condition causing point burning or
pitting is corrected, new points will provide no .
better service than the old points. Refer to
Section 6Y for an analysis of point burning or
pitting.
• Check point alignment (fig. 5) then, adjust distri-
. butor contact point gap to .019" (new points) or
.016"
(used points). Breaker arm rubbing block
must be on high point of lobe during adjustment.
NOTE: If contact points have been in service,
they should be cleaned with a point file before
adjusting with a feeler gauge.
• Check distributor point spring tension (contact
Fig. 8 - Manifold Heat Control Valve (In Line)
point pressure) with a spring gauge hooked to
breaker lever at the contact and pull exerted at 90
degrees to the breaker lever. The points should
be closed (cam follower between lobes) and the
reading taken just as the points separate. Spring
tension should be 19-23 ounces. If not within
limits,
replace.
Excessive point pressure" will cause excessive
wear on the points, cam and rubber block. Weak
point pressure permits bouncing or chattering,
resulting in arcing and burning of the points and
an ignition miss at high speed.
4.
Install rotor and distributor cap. Press all wires
firmly into cap towers.
Fig. 7 - Checking Fan Belt Tension
Fig. 9 - Manifold Heat Control Valve (V8)
CHEVROLET CHASSIS SERVICE MANUAL
Page 270 of 659
ENGINE
6-5
Service Battery and Battery Cables
1.
Measure the specific gravity of the electrolyte in
each cell (fig. 6). If it is below 1.230 (corrected to
80°F.) recharge with a slow rate charger, or if de-
sired, further check battery.
2.
Connect a voltmeter across the battery terminals and
measure the terminal voltage of the battery during
cranking (disconnect the coil primary lead at the
negative terminal during this check to prevent engine
from firing). If the terminal voltage is less than 9.0
volts at room temperature, approximately 80°
±
20°
F.,
the battery should be further checked. See
Section 6Y for further tests.
3.
Inspect for signs of corrosion on battery, cables and
surrounding area, loose or broken carriers, cracked
or bulged cases,- dirt and acid, electrolyte leakage
and low electrolyte level. !Fill cells to proper level
with distilled water or water passed through a
"demineralizer".
The top of the battery should be clean and the bat-
tery hold-down bolts properly tightened. Particular
care should be taken to see that the top of the battery
is kept clean of acid film and dirt. When cleaning
batteries, wash first with a dilute ammonia or soda
solution to neutralize any acid present and then flush
off with clean water. Keep vent plugs tight so that
the neutralizing solution does not enter the cell. The
hold-down bolts should be kept tight enough to prevent
the battery from shaking around in its holder, but
they should not be tightened to the point where the
battery case will be placed under a severe strain.
To insure good contact, the battery cables should
be tight on the battery posts. Oil battery terminal
felt washer. If the battery posts or cable terminals
are corroded, the cables should be cleaned separately
with a soda solution and wire brush. After cleaning
and before installing clamps, apply a thin coating of
petrolatum to the posts and cable clamps to help
retard corrosion.
If the battery has remained undercharged, check
for loose or defective fan belt, defective Delcotron,
high resistance in the charging circuit, oxidized
regulator contact points, or a low voltage setting.
If the battery has been using too much water, the
voltage output
is-
too high.
Service Deicotron and Regulator
The Delcotron and regulator tests during tune up con-
sist of the above battery tests; the condition of the battery
indicating further tests and adjustments as outlined in
Section 6Y.
Service Belts (Fig. 7)
Inspect belt condition.
Check and adjust if necessary for correct tension of
belt, as follows:
• Using a strand tension gauge, check the belt tension.
• Adjust belt until the specified tension is reached.
(See Tune Up Chart.)
Service Manifold Heat Valve (Figs. 8 or 9)
Check manifold heat control valve for freedom of oper-
ation. If shaft is sticking, free it up with GM Manifold
Heat Control Solvent or its equivalent.
NOTE: Tap shaft end to end to help free it up.
Tighten Manifold
Tighten intake manifold bolts to specifications in the
FLAME
ARRESTOR
FLAME
ARRESTOR
NON-VENTED\
CAP
V\ VALVE
CLOSED
POSITIVE (283 & 327)
POSITIVE
(IN LINE)
POSITIVE
(327)
POSITIVE
(396 & 427)
Fig.
10 -
Crank case
Ventilation Systems
CHEVROLET CHASSIS SERVICE MANUAL
Page 271 of 659
ENGINE 6-6
CHOKE VALVE
COMPLETELY
CLOSED
PULL UPWARD ON
ROD TO END OF
TRAVEL
BEND ROD
TO ADJUST
ROD IN BOTTOM
OF SLOT
BOTTOM OF
ROD SHOULD
EVENWITH
TOP OF
HOLE
CHOKE VALVE
CLOSED
BOTTOM OF
ROD SHOULD
BE EVEN WITH
TOP OF HOLE
TOP OF ROD
SHOULD BE EVEN
WITH BOTTOM
OF HOLE (CHOKE
CLOSED)
^..BEND ROD TO
ADJUST
_PULL DOWNWARD
ON ROD TO CON-
TACT STOP
L6 (TYPICAL)
V8 327-275 HP
V8 350-295 HP
BEND ROI
TO ADJUST
PULL UPWARD ON
ROD TO CONTACT
STOP ON BRACKET
ALL V8 (EXCEPT 327-275 HP
AND 350-295 HP)
Fig.
11 - Remote Choke Adjustment
sequence outlined on Torque Sequence Chart. A slight
leak at the intake manifold destroys engine performance
and economy.
Service Fuel Lines and Fuel Filter
1.
Inspect fuel lines for kinks, bends or leaks and cor-
rect any defects found, • • •
2.
Inspect filter and replace if plugged.
NOTE:
If a complaint of poor high speed per-
formance exists on the vehicle, fuel pump tests
described in Section 6M should be performed.
Service Cooling System
1.
Inspect cooling system for leaks, weak hoses, loose
hose clamps and correct coolant level, and service
as required.
NOTE:
A cooling system pressure test, as de-
scribed in "Additional Checks and Adjustments"
in this section, may be performed to detect
internal or external leaks within the cooling
system.
Check and Adjust Accelerator Linkage
1.
Disconnect accelerator rod at carburetor throttle
lever.
2.
Hold carburetor throttle lever in wide position.
3.
Pull accelerator rod to wide open position. (On ve-
hicles equipped with automatic transmission, pull
through detent).
4.
Adjust accelerator rod to freely enter hole in carbu-
retor throttle lever.'
NOTE:
Accelerator linkage is outlined in de-
tail in Section 6M.
5. Connect accelerator rod at throttle lever.
Service Crankcase Ventilation (Fig. 10}
All engines have either "Positive" or "Closed Positive"
ventilation systems utilizing manifold vacuum to draw
fumes and contaminating vapors into the combustion
chamber where they are burned. Since it affects every
part of the engine, crankcase ventilation is an important
function and should be understood and serviced properly.
In both "Positive" and "Closed Positive" ventilation,
air is drawn through the engine, (through a regulating
valve) into the manifold, drawing' crankcase vapors and
fumes with it to be burned. "Positive" ventilation uses a
vented-meshed cap for clean air intake to the engine,
while . "Closed Positive" ventilation system draws the
clean air from the carburetor air cleaner and has a
nonvented oil filler cap.
1.
Ventilation valve may be checked as outlined under
"Additional Checks and Adjustments".
2.
Inspect for deteriorated or plugged hoses.
3.
Inspect all hose connections.
4.
On closed positive ventilation systems, remove flame
arrestor and wash in solvent then dry with com-
pressed air.
Service Air Injection Reactor System
Inspect air injection reactor system for evidence of
leaks,
deteriorated hoses, cracked air manifolds or tubes
and loose hose clamps. Inspect air injection pump belt
condition and tension. Make all necessary repairs as
outlined in "Section 6T".
Because of the relationship between "Engine Tune Up"
and "Unburned Exhaust Gases", the condition of Engine
CHEVROLET CHASSIS SERVICE MANUAL
Page 272 of 659
ENGINE 6-7
Tune Up should be checked whenever the Air Injection
Reactor System seems to be malfunctioning. Particular
care should be taken in checking items that affect fuel-air
ratio such as the crankcase ventilation system, the car-
buretor and the carburetor air cleaner. Carburetors and
distributors for engines with the Air Injection Reactor
System are designed, particularly, for these engines;
therefore, they must not be interchanged with or replaced
by a carburetor or distributor designed for an engine
without the Air Injection Reactor System.
Choke Adjustment (Fig. 11)
With Remote Choke
1.
Remove air cleaner and check to see that choke
valve and rod move freely.
2.
Disconnect choke r*od at choke lever.
Check choke adjustment as follows:
On all except 275 hp 327 cu. in. engines, hold
choke valve closed and pull rod up against stop. The
top of choke rod end should be 1/2 - 1 rod diameter
4.
5.
above top of hole in choke valve lever.
On 275 hp 327 cu. in. engines, hold choke valve
closed and push rod down against stop on thermostat
bracket. The top of the choke rod should be 1/2 - 1
rod diameter below the top of the hole in the choke
lever.
If necessary, adjust rod length by bending rod at off-
set. (Bend must be such that rod enters choke lever
hole freely and squarely.)
Connect rod at choke lever and install air cleaner.
3.
With Manual
Choke
1.
Remove air cleaner.
2.
Push hand choke knob in to within 1/8" of instrument
panel.
3.
Loosen choke cable at carburetor bracket and adjust
cable through the clip until the choke valve is wide
open.
4.
Tighten cable clamp at carburetor bracket and check
operation of choke valve to ensure full closed and
wide open positions.
INSTRUMENT CHECK-OUT
Instrument Hook Up
Connect vacuum gauge, dwell meter, tachometer and
timing light as recommended by the manufacturer of the
equipment being used.
Check and Adjust Dwell
1.
Start engine then ch^ck ignition dwell.
.2.
If dwell is not within specifications, adjust dwell as
follows:
V8 ENGINES
• With engine running at idle, raise the adjustment
screw window-and insert an Allen wrench in the
socket of the adjusting screw (fig. 12).
• Turn the adjusting screw as required until a dwell
reading of 30° is obtained. A 2° variation is al-
lowable for wear.
• Close access cover fully to prevent the entry of
dirt into the distributor.
NOTE: If a dwell meter is not available, turn
adjusting screw clockwise until engine starts to
misfire, then turn screw one-half turn in the op-
posite direction to complete adjustment.
IN LINE ENGINES
• Remove distributor cap and recheck point setting.
If dwell is still not within specifications check the
distributor as outlined in Section 6Y.
Check Dwell Variation
Slowly accelerate engine to 1500 rpm and note dwell
reading. Return engine to idle and note dwell reading. If
dwell variation exceeds specifications, check for worn
distributor shaft, worn distributor shaft bushing or loose
breaker plate.
WINDOW
"HEX" TYPE
WRENCH
Fig.
12 - Setting Point Dwell (V8)
Fig.
13 - Ignition Timing Marks
CHEVROLET CHASSIS SERVICE MANUAL
Page 273 of 659
ENGINE
6-8
Check
and
Adjust Ignition Timing
(Fig. 13)
1.
Disconnect
the
distributor spark advance hose
and
plug
the
vacuum source opening.
2.
Start engine
and run at
idle speed
(see
tune
up
chart).
3.
Aim
timing light
at
timing
tab.
NOTE:
- The
markings
on the
tabs
are in 2°
increments
(the
greatest number
of
markings
on
the
"A"
side
of the "O"). the "O"
markings
is
TDC
of
#1 cylinder
and all
BTDC settings fall
on
the
"A"
(advance) side
of "O".
4.
Adjust
the
timing
by
loosening
the
distributor clamp
and
,
rotating
the
distributor body
as
required, then
tighten
the
clamp.
5.
Stop engine
and
remove timing light
and
reconnect
the spark advance hose.
Adjust Idle Speed
and
Mixture
(Fig. 14)
(Except when
equipped with
Air
Injection Reactor System)
1.
As a
preliminary adjustment, turn idle mixture
screws lightly
to
seat
and
back
out 2
turns.
CAUTION:
Do not
turn idle mixture screw
tightly against seat
or
damage
may
result.
2.
With engine running
at
operating temperature (choke
wide open) adjust idle speed screw
to
bring idle
speed
to
specified
rpm
(automatic transmission
in
drive, manual transmission
in
neutral).
3.
Adjust idle mixture screw
to
obtain highest steady
idle speed
(1/4
turn
out
from lean roll).
4.
Repeat Steps
2 and 3 as
needed
for
final adjustment.
5.
Shut down
the
engine, remove gauges
and
install
air
cleaner.
Adjust Idle Speed
and
Mixture
(Fig. 14)
(With
Air
Injection Reactor System)
The recommended adjustment procedure
for Air
Injec-
tion Reactor System equipped engines
is as
follows:
1.
As a
preliminary adjustment, turn idle mixture
screws lightly
to
seat
and
than back
out 3
turns.
CAUTION:
Do not
turn idle mixture screw
tightly against seat
or
damage
may
result.
2.
With engine running
at
operating temperature, choke
wide open,
and
parking brake applied, adjust idle
specified idle speed (automatic
"drive"-manual transmission
in
to
in
screw
transmission
"neutral").
;3.
Adjust idle mixture screw (turn
in) to
"lean roll"
position; then turn screw
out 1/4
turn
(1/4
turn rich
from "lean roll").
The
definition
of
"lean roll" point
is
a 20 to 30 rpm
drop
in
engine speed, obtained
by
leaning
the
idle mixture.
4.
Repeat Steps
2 and 3 as
needed
for
final adjustments.
ADDITIONAL CHECKS
AND
ADJUSTMENTS
Testing Crankcase Ventilation Valve
(Fig. 15) 0
1.
Connect tachometer
and
vacuum gauge
as for
idle
speed
and
mixture adjustment.
2.
Set
parking brake, start engine
and
adjust idle speed
and mixture.
3.
Disconnect ventilation hose
at
valve, block opening
of
valve
and
read engine
rpm
change.
4.
A
change
of
less than
50 rpm
indicates
a
plugged
ventilation valve
-
replace
the
valve.
Cylinder Balance Test
(Fig. 16)
It
is
often difficult
to
locate
a
weak cylinder.
A com-
pression test,
for
example, will
not
locate
a
leaky intake
manifold,
a
valve
not
opening properly
due to a
worn
camshaft,
or a
defective spark plug.
With
the
cylinder balance test,
the
power output
of one
cylinder
may be
checked against another, using
a set of
grounding leads. When
the
power output
of
each cylinder
is
not
equal,
the
engine will lose power
and run
roughly.
Perform
a
cylinder balance test
as
follows:
1.
Connect
the
tachometer
and
vacuum gauge.
2.
Start engine
and run at 1500 rpm.
3.
Ground large clip
of
grounding leads
and
connect
in-
dividual leads
to all
spark plugs except
the
pair being
tested.
Divide
the
firing order
in
half
and
arrange
one
half
over
the
other.
The
cylinders
to be
tested together
ap-
pear
one
over
the
other.
L4 Firing Order
V8 Firing Order
1-8-4-3-6-5-7-2
1-6, 8-5, 4-7, 3-2
1-3-4-2
= 1-3
4-2
L6 Firing Order
1-5-3-6-2-4
=
=
1-4. 3-2
1-5-3
6-2-4
1-6, 5-2, 3-4
1-8-4-3
6-5-7-2
4.
Operate engine
on
each pair
of
cylinders
in
turn
and
note engine
rpm and
manifold vacuum
for
each pair.
A variation
of
more than
1
inch
of
vacuum
or 40 rpm
between pairs
of
cylinders being tested indicates that
the cylinders
are off
balance.
Battery
The battery should
be
checked with special testing
equipment
and to the
equipment manufacturers specifica-
tions.
See
Section 6Y
for
complete information
on
battery
tests.
Ignition
The following additional ignition checks
may be
made
with
any of
several pieces
of
equipment available
for un-
covering
the
source
of
engine difficulties.
The
specific
operating instructions
of the
equipment manufacturer
should
be
followed:
Cranking voltage
Ignition switch
Distributor resistance
Secondary resistance
Ignition output
and
secondary leakage
Cranking Voltage
(Fig. 17)
1.
Disconnect coil primary lead
at the
coil negative
terminal
to
prevent engine from firing during
cranking.
2.
Connect voltmeter between primary terminal
of coi|
(resistance wire side)
and
ground.
3.
Operate starting motor.
CHEVROLET CHASSIS SERVICE MANUAL
Page 274 of 659
ENGINE
6-9
ROCHESTER
BV
IDLE
MIXTURE
ROCHESTER
2GV
HOLLEY 2300C
(PRIMARY)
IDLE
MIXTURE
SPEED
HOLLEY 2300
(SECONDARY)
LE IDLE
MIXTURE SPEED
MANUAL CHOKE
CARTER
YF
IDLE
MIXTURE
AUTOMATIC CHOKE
IDLE
MIXTURE
IDLE
SPEED
ROCHESTER
4MV
IDLE
MIXTURE
SIDE INLET
HOLLEY 4150
CENTER INLET
IDLE
MIXTURE
IDLE
MIXTURE
HOLLEY 4160
IDLE
MIXTURE
APPLICATION |
CARBURETOR
IN LINE
153
90
194
120
230
140
250
155
V-8
283
195
210
327
275 300 325 350
350
295
396
325 350
427
385 390 400 425 435
ROCH.
BV
1234
ROCH 2GV
1234
ROCH
4MV
1234
1-2
CARTER
YF
Man.
Auto.
2-4
1234
HOLLEY
4150
Side
Center
HOLLEY
4160
HOLLEY
2300
C Prim.
Sec.
Fig.
14 - Idle Speed and Mixture Screws
CHEVROLET CHASSIS SERVICE MANUAL