
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 

ENGINE 6-19
OIL SEAL (REAR MAIN)
Replacement
The rear main bearing oil seal can be replaced (both
halves) without removal of the crankshaft.
NOTE:
 Always replace the upper and lower
seal as a unit. Install with the lip facing toward
the front of the engine.
1.
 With the oil pan removed, remove the rear main
bearing cap.
2.
 Remove oil seal from the groove by lifting the end
tab (fig. 7L) then clean seal groove.
3.
 Lubricate the lip and O.D. of a new seal with engine
oil. Keep oil off the parting line surface. Insert
seal in cap and roll it into place with finger and
thumb,
 using light pressure so beads on seal O.D.
are not cut by seal groove at cap parting line. Be
sure tabs on seal are properly located in cross
grooves.
4.
 To remove the upper half of the seal, use a small
hammer to tap a brass pin punch on one end of seal
until it protrudes far enough to be removed with
pliers (fig. 8L).
NOTE:
 Always clean crankshaft surface re-
moving all foreign deposits before installing a
new seal. Also clean seal groove.
5. Lubricate the lip and O.D. of a new seal with engine
oil. Keep oil off the parting line surface. Gradually
push with a hammer handle, while turning crank-
shaft, until seal is rolled into place. (Similar to in-
stalling a main bearing.) Be careful that seal bead
on O.D. is not cut. Compress seal towards crank-
shaft as much as possible.
6. Install the rear main bearing cap (with new seal) and
torque to specifications. Be sure cross seal tabs
are in place and properly seated.
CRANKSHAFT PULLEY AND HUB
(Chevy II with L4 Engine)
Removal
1.
 Drain radiator and disconnect upper and lower radi-
ator hoses at radiator.
2.
 Remove radiator core as outlined in Section 13.
3.
 Remove fan belt. Remove crankshaft pulley from
pulley hub.
4.
 Install puller Tool J-6978 to pulley hub with two
3/8"
 x 2" and one 5/16" x 2" bolts and remove hub
then remove puller tool.
Installation
1.
 Coat oil seal contact area on hub with engine oil
position hub over crankshaft and key and start hub
into position with a mallet. Using Tool J-5590 drive
onto crankshaft until it bottoms against crankshaft
gear.
NOTE:
 Crankshaft extends slightly through hub
and a tool is necessary to drive hub completely
into bottomed position.
2.
 Install pulley onto hub.
NOTE:
 There are two 3/8" holes and one
5/16" hole that must be matched on hub in order 
Fig.
 9L - Removing Torsional Damper
to properly position timing mark.
3.
 Install fan belt and adjust using strand tension gauge.
4.
 Install radiator as outlined in Section 13.
TORSIONAL DAMPER
Removal
1.
 Remove radiator core, as outlined in Section 13.
2.
 Remove fan belt and (if so equipped) accessory drive
pulley and belt.
3.
 Install Tool J-6978 to damper and turn puller screw
to remove damper (fig. 9L). Remove tool.
Installation
1.
 Coat front cover oil seal contact area of damper with
engine oil.
CAUTION: It is necessary to use installer
Tool J-22197 to prevent the inertia weight sec-
Fig.
 10L - Installing Torsional Damper
CHEVROLET CHASSIS SERVICE MANUAL 

ENGINE 6-26
6. Remove lifting device and lifting adapter then install
rocker arm covers as outlined.
7.
 On synchromesh equipped vehicles, install clutch
cross-shaft engine bracket, then adjust and connect
clutch as outlined in Section 7.
8. Connect:
• Speedometer cable.
• Shift linkage at transmission.
• Transmission cooler lines (if so equipped).
9. Install propeller shaft.
10.
 Remove jack stands and lower vehicle.
11.
 Connect: \ '
Power steering pump lines (if so equipped).
Vacuum line to power brake unit (if so equipped).
Exhaust pipes at manifold flanges.
Accelerator linkage at pedal lever.
Fuel line at fuel pump.
Engine cooler lines (if so equipped).
Oil pressure gauge lines (if so equipped).
12.
 Connect wires at:
Coil
Oil pressure switch
Temperature switch
Delcotron
Starter solenoid
13.
 Install pulley, fan blade and fan belt as outlined in
Section 6K.
14.
 Install radiator and shroud as outlined in Section 13.
15.
 Install and adjust hood as outlined in Section 11.
16.
 Connect battery cables.
17.
 Fill with coolant, engine oil and transmission oil,
then start engine and check for leaks.
18.
 Perform necessary adjustments and install air
cleaner.
INTAKE MANIFOLD
Removal
1.
 Drain radiator and remove air cleaner.
2.
 Disconnect:
Battery cables at battery.
Upper radiator and heater hose at manifold.
Accelerator linkage at pedal lever.
Fuel line at carburetor. ;
Wires at temperature sending switch and coil
(both sides).
Power brake hose at carburetor base.
Spark advance hose at distributor.
Crankcase ventilation hoses (as required).
3.
 Remove distributor cap and mark rotor position with
chalk. Remove distributor clamp and distributor,
then position distributor cap rearward clear of
manifold.
4.
 Remove coil.
5.
 Remove manifold-to-head attaching bolts, then re^
move manifold, (with carburetor on) from engine and
discard gaskets and seals.
6. If manifold is to be replaced,,transfer:
Carburetor and carburetor mounting studs.
Temperature sending switch.
Water outlet and thermostat (use new gasket).
Heater hose adapter.
Choke coil.
Installation
1.
 Clean gasket and seal surfaces of manifold, cylinder 
heads and block.
2.
 Install manifold end seals on block as shown (fig.
2V).
3.
 Install side gaskets on cylinder heads using sealing
compound around water passages (fig. 2V).
4.
 Install manifold bolts, and torque to specifications in
the sequence outlined on the Torque Sequence Chart.
5.
 Install coil.
6. Install distributor with the rotor pointing at the chalk
mark, then install distributor cap.
NOTE:
 If the crankshaft has been rotated while
the distributor was removed, time distributor to
number 1 cylinder as outlined in Section 6Y.
7.
 Connect:
Battery cables at battery.
Upper radiator and heater hose at manifold.
Accelerator linkage at pedal lever.
Fuel line at carburetor.
Wires at temperature sending switch and coil
(both sides)!
Power brake hose at carburetor base.
Spark advance hose at distributor.
Crankcase ventilation hoses (as required).
Fill with coolant, start engine, check for leaks and
adjust timing and carburetor idle speed and mixture.
EXHAUST MANIFOLD
Removal
NOTE:
 If equipped with "Air Injection Reactor
System", remove air manifold and tubes as out-
lined in Section 6T.
1.
 Disconnect battery ground cable.
 -
2.
 Disconnect and remove Delcotron (as required).
3.
 On 396 and 427 cu. in. engines, remove spark plugs
Fig. 2V - Intake Manifold Gasket and Seal Location
CHEVROLET CHASSIS SERVICE MANUAL