Engine Data - Westerbeke W70GA Service Manual

ENGINE DATA
DESCRIPTION
The engine is a "Square" type with a total displacement of
2184cc. It is a watercooled, four cylinder engine with a belt-
driven overhead cam (OHC).
The main specifications are as follows:
COMBUSTION CHAMBER TYPE Multi-sphere type
BORE X STROKE 86mm x 94mm
TOTAL DISPLACEMENT 2184cc
COMPRESSION RATIO 8.6
COMPRESSION PRESSURE 11.5 kg/cm2- 270 rpm
CYLINDER.BLOCK
The cylinder block construction is an integral design where
the block and cylinder liners are cast as one piece. The
cylinder walls are double honed for a fine, precision surface.
The cylinder block is deep-skirted with chambered cross
sections to reduce noise. There are five main bering journals
for crankshaft support.
,1
CYLINDER HEAD
This WES'IERBEKE engine is an overhead cam (OHC),
cross-flow design. The rocker
arm
assembly bolts
independently to the head, rather than using the head bolts.
This makes it possible to remove the cylinder head without
disassembling the rocker
arm
assembly (and vice-versa)
resulting in improved serviceability. The intake and exhaust
ports
are located
on opposite sides of the cylinder head
(cross-flow) and the intake ports are designed to swirl the
incoming fueUair mixture.
CRANK MECHANISM
The piston is a tapered
type
with a recessed combustion
surface, specifically designed for the engine. The piston pin
is offset Imm to the thrust side (direction of lateral pressure
durillg combustion stroke) to decrease knocking noise.
On
the crankshaft, the outside of the balance. weight is made
thicker to improve the effectiveness of a single,weight,
reducing the conventional eight weights to four.
As a result, the inertial weight is reduced, improving epgine
response.
End play of the crankshaftis restricted
~y
a
~t
·
bearing at the No.3 main bearing journal.
'·
VALVE MECHANISM
The valve mechanism employs the overhead camshaft
(OFIC). The rocker arm is offset against the exhaust stem to
prevent carbon damage and irregular.
The valve spring is of the double coil type with unequal pitch
inner and outer springs. It is necessary to set the shorter
pitched side toward cylinder head at the time of installation.
The end play of the camshaft cannot be adjusted. Positioning
of the camshaft and cylinder head are determined by the
flange on the cam.
The adjustment of the belt is carried out by the tensioner and
tension spring.
INTAKE AND·EXHAUST SYSTEM
Both intake
and exhaust manifolds·are
of aluminum,
consisting of an independent
branch,
pipe for each pair
of
cylinders.
COOLING SYSTEM
A
centrifugal water pump is incorporated in the cylinder
block, driven by the timing belt A wax type thennostat is
employed to
ensure
proper temperature control. Cooling is
provided by a belt driven raw water pump and a heat
exchanger.
LUBRICATION SYSTEM
A
crescent
type
oil
pump
is driven
directly by
the crankshaft
to
feed oil under pressure.
The
oil
fiher
is.:ijill-tlow
and
a
spin -on
type.
FUEL SYSTEM
The carburetor
is
a
down-draft, one stage, single
barrel
and the
fuel
pump
is an electromagnetic type, It performs the
pumping
:function
through
the reciprocating motion of a plunger.
A mechanical belt driven governor connected the
to
throttle arm
of
the carburetor
controls the
engine
rotational
speed,
power
output
ands torque.
·Nm:
For "additional tnjormati0n, refer to the. ·
.ENGWGENERATOR SPECIFICATIONS in'.this 11f21"ual
MEASURING EXHAUST BACK PRESSURE
PSI
GAUGE
Exhaust systems normally produce resistance
to
the flow
of
·exhaust gases, causing back-pressure. Back-pressure
must
be
kept within a certain limit.
Check
the back-pressure before
. the generator
is put back into service.
To test exhaust pressure, connect either a
water
column or
PSI tube.to the test
part
on the exhaust elbow as shown.
ChCck ~e exhaust back-pressure before the generator
is put
into service.
Measure
the back-pressure after the engine has
reached its nomial operating temperature, and
at
the point
where it
is
about
to
reach its rated load at either 1500 rpm
(for SOHz applications) or 1800
rpm
(for 60Hz appli'i.ations). •
Back-pressure
should not exceed 1.5 psi (0.11 kg/cm
J.
A water column can
be
made
by taping
one end
of
a clear
plastic tube along a yardstick lll!d.
fittin~
the other end of the
tube
with a l/4".NPf pipe fitting._. . · • . · ·
Back-pressure
should
nof exceed 27in (69cm)
·of water
ui
the
water column.
Engines & Generators
3
/·
,,
NiEASURiNG
EXHAUST .BACK
P-5SURE