Pontiac Fiero 1988 Service Manual page 326

2.8 LITER V-6 ENGINE P CARLINE 6A2-1
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SECTION 6A2
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C O N T E N T S
G E N E R A L D E S C R I P T I O N
6A2-1
E N G I N E
LUBRICATION . .... 6A2-2
O N C A R SERVICE
Engine Assembly 6A2-7
Powertrain Mounts .................................... 6A2-7
Rocker Arm Cover 6A2-10
Intake Manifold
6A2-12
Exhaust Manifold 6A2-12
Valve Mechanism 6A2-14
Valve Stem Oil Seal and/or
Valve Spring ........................................... 6A2-15
Valve Lifters 6A2-16
Cylinder Head 6A2-17
Torsional Damper 6A2-18
Crankcase Front Cover 6A2-18
Oil Seal (Front Cover) 6A2-19
Timing Chain & Sprocket .......................... 6A2-19
Camshaft 6A2-20
Oil Pan 6A2-20
Oil Pump 6A2-21
Connecting Rod and Main Bearings 6A2-21
Pistons, Rings & Connecting Rods 6A2-21
Crankshaft .................................................. 6A2-22
S P E C I F I C A T I O N S
6A2-22
"FOR VEHICLES SOLD IN CANADA AND
EQUIPPED WITH NON-CLOSED LOOP ENGINES, ALSO
REFER TO THE APPROPRIATE CANADIAN SERVICE
MANUAL SUPPLEMENT."
GENERAL DESCRIPTION
C Y L I N D E R B L O C K
The cylinder block is made of cast alloy iron and
has 6 cylinders arranged in a "V" shape with 3
cylinders in each bank. The cylinder banks are set at
a 60° angle from each other.
The right bank cylinders (1, 3, 5) are on the rear
of the car. Cylinders (2, 4, 6) left bank, are on the
bulkhead side of the car.
Four main bearings support the crankshaft,
which is retained by bearing caps that are machined
with the block for proper alignment and clearances.
C Y L I N D E R H E A D
The cast alloy iron cylinder heads have individual
intake and exhaust ports for each cylinder. Valve
guides are integral and rocker arms are retained on
individual threaded studs.
C R A N K S H A F T & B E A R I N G S
The crankshaft is cast nodular iron, with deep
rolled fillets on all six crankpins and two center main
journals. Four steel backed aluminum bearings are
used, with # 3 bearing being the end-thrust bearing.
C A M S H A F T & D R I V E
The camshaft is cast alloy iron with tapered 13.2
mm wide lobes, offset from the lifters and tapered to
provide positive valve lifter rotation. The camshaft is
supported by four journals and includes a
distributor/oil pump drive gear. A 3/8" pitch chain
drives the camshaft through a hardened sintered iron
sprocket. The crankshaft sprocket is also hardened
sintered iron, and is pressed onto the nose of the
crankshaft. A rubber snubber is used to dampen chain
motion.
P I S T O N S & C O N N E C T I N G R O D S
The pistons are cast aluminum, with steel struts,
using two compression rings and one oil control ring.
The piston pin is offset 1.5 mm toward the major thrust
side. This allows a gradual change in thrust pressure
against the cylinder wall as the piston travels its path.
Pins are chromium steel and have a floating fit in the
pistons. They are retained in the connecting rods by a
press fit.
Connecting rods are made of forged steel. Full
pressure lubrication is directed to the connecting rods
by drilled oil passages from the adjacent main bearing
journal.
V A L V E T R A I N
A very simple ball pivot-type rocker train is used.
Motion is transmitted from the camshaft through the
hydraulic lifter and push rod to the rocker arm. The
rocker arm pivots on its ball and transmits the
camshaft motion to the valve. The rocker arm ball
locates on a stud, threaded into the head, and is
retained by a nut. The push rod is located by a guide
plate held under the rocker arm stud, assuring that the
rocker arm operates in the plane of the valve.
I N T A K E M A N I F O L D
The intake manifold for vehicles equipped with
MPFI is a three-piece cast aluminum unit. It centrally
supports a fuel rail with 6 fuel injectors. Refer to
Section 6C3 for MPFI sub-assembly removal.