
HEATER AND AIR CONDITIONING 1A-76
Fig.
112—-Heater Core Removal—Four-Season System (Corvette)
3.
Replace the core case into the car as described
under Heater and Air Distributor Assembly.
COMPRESSOR
The same basic six.cylinder reciprocating compressor
is used in all systems.
Two variations of the basic compressor are used. One,
with a displacement of 12.6 cu. in. is used with the Four-
Season System. The second model, having displacement
of 10.8 cu. in. is used with the Universal and All-Weather
Systems.
AH Systems
Removal
1.
Purge the refrigerant from the system.
2.
Remove connector attaching bolt and connector. Seal
connector outlets.
3.
Disconnect electrical lead to clutch actuating coil.
4.
Loosen brace and pivot bolts and detach belt.
5. Remove the nuts and bolts attaching the compressor
brackets to the mounting bracket.
6. Before beginning any compressor disassembly, drain
and measure oil in the compressor. Check for
evidence of contamination to ..determine if remainder
of system requires servicing. Compressor Servicing
information is located in the Chassis Overhaul
Manual.
Installation
1.
li oil previously drained from the compressor upon
removal shows no evidence of contamination, replace
a like amount of fresh refrigeration oil into the com-
pressor before reinstallatLon. If it was necessary to
service the entire system because of excessive con-
tamination in the oil removed, install a full charge of
"fresh refrigeration oil in the compressor. (See
Checking Compressor Oil Charge under Checking
Oil)
2.
Position compressor on the mounting bracket and
install all nuts, bolts and lock washers.
3.
Install the connector assembly to the compressor
rear head, using new "O" rings.
4.
Connect the electrical lead to the coil and install
and adjust compressor belt.
5. Evacuate and charge the system.
6. Leak test the system and check for proper operation.
Fig.
113—Heater Hoses^-Four-Season System (Corvette)
CHEVROLET CHASSIS SERVICE MANUAL

CORVETTE BODY 1B-28
Fig. 63—Spare Tire Mount
1.
Cover
2.
Strap Assembly
3. Strap Assembly
Pivot Bolt
Swivel Bolt Nut
Swivel Lock Bolt
Swivel Bolt
Bracket
7. Swivel Bolt Pin
8. Tray
9. Lock Case
10.
Lock Cover
1.
Panel Roof Trim
2.
Panel Retaining
Screw
3. Washer
4.
Chart Molding
5. Screw - Rear
Quarter Trim
Panel Retaining
Fig.
64—Rear Body Trim
6.
"J"
Nut - Rear
Quarter Trim
Panel Retaining
7. Panel Assembly - Rear
Quarter Trim
8. Cover - Rear Lower
9. Cement - 3M-1711
or Equivalent
plastic body panels. The general area around the welding
operation should be protected with wet asbestos or any
other like method (several thicknesses of aluminum foil
makes an excellent heat shield if out of the way of direct
flame).
Straightening of steel parts while still in body must be
done with care. When applying hydraulic jacks or like
equipment which operates by exerting force, bear in
mind that the part being used to brace the stationary end
of tool must be able to withstand such usage and that
fiber glass parts, though tougher than steel, will not yield
or "take a set" as with steel parts, so naturally they
cannot be "straightened". If poor alignment exists due
to collision or other physical damage, check steel re-
inforcements in cowl, roof and sill areas (fig. 69) with
care.
Tracing line of damaging force and checking body
carefully for broken bonds and cracks before, during
and after repairs will pay off repeatedly.
Small cracks and faults in bonds and panels will usually
grow larger if left unattended.
REPAIR PANELS
Body repair panels are illustrated in Figures 66
through 70. Those shown are typical of panels which are
available through Chevrolet parts sources. Procedures
which may be used for installing panels are explained in
the following pages.
Figure 71 illustrates various bonds which will be en-
countered during repair procedures. The legend for
Figure 71 cites typical applications for bonds shown.
CHEVROLET CHASSIS SERVICE MANUAL

FRONT SUSPENSION ,3-13
6. Carefully lower the inner end of the control arm.
Tension on the spring will be removed before the
spring can be removed from the vehicle.
7.
Remove the spring.
Installation
1.
With the suspension set up as in Step 2 of the disas-
sembly procedure, insert a block of wood between the
upper control arm and the spring tower to keep the
arm up out of the way.
2.
Set the spring in place on the crossmember after
checking on proper positioning necessary.
3.
Install the steel bar and wood block as shown in Fig-
ure 20 and lift the control arm up until the inner
pivot cam bolt can be installed. ,
4.
Install the outer cam and loosely install the lock
washer and nut
5.
Set the cam bolt on the mark scribed during the re-
moval procedure and hold in this position while tight-
ening the nut (See specifications at the end of this
book).
6. Replace the strut rod to lower control arm nuts,
bolts and lock washers, the stabilizer bar link, the
shock absorber, the tie rod end, and the wheel and
tire.
7.
Lower vehicle to floor and install the shock absorber
upper stem retaining nut retainer and grommet.
8. Check the camber adjustment.
Chevelle and Camaro
Removal
1.
With an open end wrench hold the shock absorber up-
per stem from turning, and then, remove the upper
stem retaining nut, retainer and rubber grommet.
2.
With the car supported by the frame so that the con-
trol arms hang free, remove the wheel and tire as-
sembly (replace one wheel nut to retain the brake
drum),
shock absorber, and stabilizer bar to lower
control arm link.
4.
5.
Fig.
21 - Front Spring Removal - Chevelle & Camaro
Place a steel bar (fabricated as shown in Figure 19)
through the shock absorber mounting hole in the
lower control arm so that the notch seats over the
bottom spring coil and the bar extends outboard be-
yond the end of the control arm and slightly toward
the front of the car.
With a suitable jack or hoist lift up slightly on the
end of the bar.
Remove the lower ball stud cotter pin and attaching
nut and remove the ball stud from the knuckle.
ALTERNATE METHOD
Fig.
22 - Removing or Installing Front Coil Spring - Corvette (Typical)
CHEVROLET CHASSIS SERVICE MANUAL

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

ENGINE 6-15
2.
Install rocker arms, rocker arm balls and rocker
arm
nuts.
\
Tighten rocker arm nuts until all lash is
eliminated. .
3.
Adjust valves when lifter is on base circle of cam-
shaft lobe as follows:
a. Mark distributor housing, with chalk, at each cyl-
inder position (plug wire) then disconnect plug
wires at spark plugs and coil and remove distri-
butor cap and plug wire assembly (if not previ-
ously done).
b.
Crank engine until distributor rotor points to
number one cylinder position and breaker points
are open. Both valves on number one cylinder
may now be adjusted.
c. Back out adjusting nut until lash is felt at the push
rod then turn in adjusting nut until all lash is re-
moved. This can be determined by checking push
rod side play while turning adjusting nut (fig. 2L).
When play has been removed, turn adjusting nut
in one full additional turn (to center lifter
plunger).
d. Adjust the remaining valves, one cylinder at a
time,
in the same manner.
4.
Install distributor cap and spark plug wire assembly.
5.
Install rocker arm cover as outlined.
6. Adjust carburetor idle speed and mixture.
VALVE LIFTERS
Hydraulic valve lifters very seldom require attention.
The lifters are extremely simple in design readjustments
are not necessary, and servicing of the lifters requires
only that care and cleanliness be exercised in the han-
dling of parts.
Locating Noisy Lifters
Locate a noisy valve lifter by using a piece of garden
Fig.
2L - Valve Adjustment
hose approximately four feet in length. Place one end of
the hose near the end of each intake and exhaust valve
with the other end of the hose to the ear. In this manner,
the sound is localized making it easy to determine which
lifter is at fault.
Another method is to place a finger on the face of the
valve spring retainer. If the lifter is not functioning
properly, a distinct shock will be felt when the valve
returns to its seat.
The general types of valve lifter noise are as follows:
1.
Hard Rapping Noise--Usually caused by the plunger
becoming tight in the bore of the lifter body to such
an extent that the return spring can no longer push
the plunger back up to working position. Probable
causes are:
a. Excessive varnish or carbon deposit causing
abnormal stickiness.
b.
Galling or "pickup" between plunger and bore of
lifter body, usually caused by an abrasive piece
of dirt or metal wedging between plunger and
lifter body.
2.
Moderate Rapping Noise--Probable causes are:
a. Excessively high leakdown rate.
b.
Leaky check valve seat.
c. Improper adjustment.
3.
General Noise Throughout the Valve Train—This
will, in almost all cases, be a definite indication of
insufficient oil supply, or improper adjustment.
4.
Intermittent Clicking—Probable causes are:
a. A microscopic piece of dirt momentarily caught
between ball seat and check valve ball.
b.
In rare cases, the ball itself may be
out-of-
round or have a flat spot.
c. Improper adjustment.
In most cases where noise exists in one or more lifters
all lifter units should be removed, disasssmbled, cleaned
in a solvent, reassembled, and reinstalled in the engine.
If dirt, varnish, carbon, etc. is shown to exist in one unit,
it more than likely exists in all the units, thus it would
only be, a matter of time before all lifters caused trouble.
Removal
1.
Remove valve mechanism as outlined.
2.
Mark distributor housing, with chlak, at each cylin-
der position (plug wire) then disconnect plug wires at
spark plugs and coil and remove distributor cap and
plug wire assembly.
3.
Crank engine until distributor rotor points to number
one position, then disconnect distributor primary lead
at coil and remove distributor.
4.
Remove push rod covers (discard gaskets).
5.
Remove valve lifters.
NOTE: Place valve lifters in a rack so they
may be reinstalled in the same location.
Installation
1.
Install valve lifters.
NOTE:
Whenever new valve lifters are being
installed, coat foot of valve lifters with Molykote
or its equivalent.
2.
Install push rod covers, using new gaskets, and
torque bolts to specifications.
3.
Install distributor, positioning rotor to number one
cylinder position, then connect primary lead at coil.
4.
Install and adjust valve mechanism as outlined.
CHEVROLET CHASSIS SERVICE MANUAL

ENGINE 6-21
CAUTION: Support cover
•
at sealing area.
(Tool J-971 may be used as support.)
Without Cover
Removal
1.
With crankshaft pulley and nub or torsional damper
removed, pry old seal out of cover from the front
with a large screw driver, being careful not to dam-
age the seal surface on the cover.
2.
Install new seal so that open end of seal is toward the
inside of cover and drive it into position with Tool
J-8340 (fig. 13L).
CAMSHAFT
Measuring Lobe Lift
NOTE: Procedure is similar to that used for
checking valve timing.. If improper valve
operation is indicated, measure the lift of each
push rod in consecutive order and record the
readings.
1.
Remove valve mechanism as outlined.
2.
Position indicator with ball socket adapter on push
rod (fig. 14L).
3.
Rotate the crankshaft slowly in the direction of rota-
tion until the lifter is on the heel of the cam lobe.
At this point, the push rod will be in its lowest
position.
4.
Set dial indicator on zero, then rotate the crankshaft
slowly, or attach an auxiliary starter switch and
"bump" the engine over, until the push rod is in the
fully raised position.
CAUTION: 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.
Fig.
15L - Timing Gear Marks
5.
Compare the total lift recorded from the dial indica-
tor with specifications.
6. Continue to rotate the crankshaft until the indicator
reads zero. This will be a check on the accuracy of
the original indicator reading.
7.
If camshaft readings for all lobes are within specifi-
cations, remove dial indicator assembly.
8. Install and adjust valve mechanism as outlined.
Removal
1.
Remove valve lifters as outlined,
2.
Remove crankcase front cover as outlined.
3.
Remove radiator as outlined in Section 13.
4.
Remove grille as outlined in Section 13.
5.
Remove fuel pump as outlined in Section 6M.
6. Align timing gear marks then remove the two cam-
shaft thrust plate bolts by working through holes in
Fig.
ML - Measuring Camshaft Lobe Lift
Fig.
16L - Checking Camshaft Gear Runout
CHEVROLET CHASSIS SERVICE MANUAL

ENGINE 6-36
Fig.
23V - Installing Crankshaft Sprocket
(283,
327
and
350)
8* Draw camshaft sprocket onto camshaft, using the
three mounting bolts. Torque to bolt specifications.
9. Lubricate timing chain with engine oil.
10.
Install crankcase front cover and torsional damper
as outlined.
CAMSHAFT
Measuring Lobe Lift
NOTE: Procedure is similar to that used for
checking valve timing. If improper valve opera-
tion is indicated, measure the lift of each push
rod in consecutive order and record the
readings.
1.
Remove valve mechanism as outlined.
2.
Position indicator with ball socket adapter on push
rod (fig. 26V).
3.
Rotate the crankshaft damper slowly in the direction
of rotation until the lifter is on the heel of the cam
lobe.
At this point, the push rod will be in its lowest
position.
Fig.
25V- Installing Timing Chain
Fig.
24V - Installing Crankshaft Sprocket
(396 and 427)
Fig.
26V - Measuring Camshaft Lobe Lift
CHEVROLET CHASSIS SERVICE MANUAL

MAINTENANCE AND ADJUSTMENTS
ENGINE-ELECTRICAL 6Y-19
PERIODIC MAINTENANCE
BREAKER POINT SYSTEM
The distributor breaker points and spark plugs are the
only ignition system components that require periodic
service. The remainder of the ignition system requires
only periodic inspection to check operation of the units,
tightness of the electrical connections, and condition of
the wiring. When checking the coil, test with a reputable
tester.
Breaker type distributors are equipped with cam lubri-
cator and should have the wick replaced at the same time
contact point set is replaced. It is not necessary to
lubricate the breaker cam when using a cam lubricator.
Do not attempt to lubricate the wick - Replace when
necessary. When installing a new wick, adjust its posi-
tion so the end of the wick just touches the lobe of the
breaker cam.
Distributor shaft lubrication is accomplished by a
reservoir of lube around the mainshaft in the distributor
body.
BREAKERLESS SYSTEM
Since there are no moving parts in the ignition pulse
amplifier unit mounted forward of the radiator bulkhead,
and the distributor shaft and bushings have permanent
type lubrication, no periodic maintenance is therefore
required for the breakerless ignition system. The dis-
tributor lower bushing is lubricated by engine oil through
a splash hole in the distributor housing, and a housing
cavity next to the upper bushing contains a supply of
lubricant which will last between overhaul periods. At
time of overhaul, the upper bushing may be lubricated
by removing the plastic seal and then adding SAE 20 oil
to the packing in the cavity. A new plastic seal will be
required since the old one will be damaged during
removal.
Tachometer readings for test purposes can be made on
the primary circuit of the breakerless ignition system in
the same manner as on the conventional ignition system,
however before attempting to connect a test tachometer
into the primary circuit check with your instrument
supplier to insure that satisfactory readings can be
obtained and the breakerless system will not be damaged
by the tachometer that is to be used,
IGNITION COIL CHECK (BREAKERLESS)
The ignition coil primary can be checked for an open
PULSE
AMPLIFIER
IGN. SWITCH WIRE
"("IGN" TERMINAL)
-E3 IJU
12
WHITE-
-20 BLACKf' • 12 WHITE-
Fig.
3i—
Breakerless Ignition System
condition by connecting an ohmmeter across the two
primary terminals with the battery disconnected. Pri-
mary resistance at 75
°F.
should be between .35 and .55
ohm. An infinite reading indicates the primary is open.
For the engine to run but miss at times, the primary
open may be of the intermittent type.
The coil secondary can be checked for an open by con-
necting an ohmmeter from the high tension center tower
to either primary terminal. To obtain a reliable reading,
a scale on the ohmmeter having the 20,000 ohm value
within, or nearly within, the middle third of the scale
should be used. Secondary resistance at 75°F. should be
between
8,000
and 12,500 ohms. If the reading is infinite,
the coil secondary winding is open.
A number of different types of coil testers are avail-
able from various test equipment manufacturers. When
using these testers, follow the procedure recommended
by the tester manufacturer.
tester will properly
NOTE:
Make sure the
check this special coil.
SPARK PLUGS
Should be removed, inspected cleaned and regapped at
tune-up. Defective plugs should be replaced, see Servic-
ing of Units Off the Vehicle.
SERVICE OPERATIONS
DISTRIBUTOR CONTACT POINTS
CLEANING
Dirty contact points should be dressed with a few
strokes of a clean, fine-cut contact file. The file should
not be used for other metals and should not be allowed to
become greasy or dirty. Never use emery cloth to clean
contact points. Contact surfaces, after considerable use,
may not appear bright and smooth, but this is not neces-
sarily an indication that they are not functioning satis-
factorily. Do not attempt to remove all roughness nor
dress the point surfaces down smooth; merely remove
scale or dirt.
Badly burned or pitted contact points should be re-
placed and the cause of trouble determined so it can be
eliminated. High resistance or loose connections in the
condenser circuit, oil or foreign materials on the contact
surfaces, improper point adjustment or high voltages may
CHEVROLET CHASSIS SERVICE MANUAL