Chevrolet 70 1969 Series, Shop Manual

Page: 672 / 913

SEC T IO N 6
ENGINES
C O N T EN T S OF THIS SEC T IO N
Page
V6 Gasoline Engine O v e r h a u l.............................................. 6-1
6A -V 6 GASOLINE ENGINES
IN D E X
Page
General Description V6 Gasoline E ng in e s............... 6-1
Engine O v e r h a u l................................................................ 6-4
Disassem bly...................................................................6-4
A sse m b ly ...........................................................................6-24
Fuel Pump O v e rh a u l......................................................6-37
C arburetor O v e rh a u l......................................................6-38
GENERAL DESCRIPTION
Chevrolet 6-cylinder 60 degree, V-type engine has two
banks of cylinders with overhead valve mechanism. En­
gines used in vehicles covered in this manual are designat­
ed as 401M and 478M.
Figure 1 shows typical accessory installation on 478M
engine. Sectional and cut-away views of typical V-6 e n ­
gine are shown in Figures 2 and 3.
The paragraphs which follow describe the various en­
gine components under respective headings. Unless other­
wise indicated, the descriptions apply to all V-6 engines.
CYLINDER BLOCK AND CRANKCASE
Cylinder block is cast integral with crankcase.
A flange is provided at botto m of crankcase skirt
for attaching oil pan.
Both the crankshaft and the camshaft are supported in
cylinder block. Four camshaft bearings are pressed into
bores in block, while crankshaft bearings are insert type
locked in place by bearing caps which are interference fit
in broached seats in block casting.
Cylinder bores are not directly opposite each other, but
are staggered with separate crankpin for each connecting
rod.
Drilled passages carry lubricating oil from oil pum p to
the various moving parts of engine as described later
under “ Lubrication System.”
Cylinder blocks are cast with space for coolant co m ­
pletely surrounding each cylinder from top to bottom.
Core holes, bearing bores, and other openings are closed
with plugs or plates.
CRANKSHAFT AND BEARINGS
Crankshafts for the 4 0 1M and 478M engines have
forged crankshafts with Tocco-hardened bearing journals.
All crankshaft bearing surfaces are carefully ground and
Figure 1— Typical V -6 , M o d e l 4 7 8 M E n gin e
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L