MG MGB User Manual

A
THE ENGINE
Fig.
A.l7
The
lobe clearance
should
not
exceed
.006
in.
(.152
mm.)
when the
oil
pump
rotors
are
in the
positions illustrated
Reassembly
is
a
reversal
of
the
dismantling
procedure
noting
the following
points:
1.
Lubricate
all
parts
with
clean
engine oil.
2.
Ensure
that the
outer
rotor
is installed
in
the
pump
body
with
its
chamfered
end
at
the
driving
endof
the
rotor
pocket
in
the
pump
body.
3. After
reassembling
check
the
pump
for
freedom
of
action.
Section
A.l3
MAIN
AND
BIG-END
BEARINGS
Unless
the
bearing
journals
are
badly
worn
the
big-end
bearings
may
be
renewed without
removing
the crankshaft.
To
renew
the
main
bearings
it is
necessary
to
withdraw
the
crankshaft.
Liners
are
used for
both
the
main
and the
big-end
bearings, which
are
of the
shimless
type
and
therefore
non-adjustable.
Big—end
bearings
Drain
the
engine
oil
and
remove
the
sump
as
in Section
A.ll.
As the bearings
are
of the
shimless
type
it is essential that
no
attempt
should
be made
to
adjust
bearings
which
are
worn.
Always ■t
new
bearings
in
place of
worn
parts.
If the
crankshaft
journals
are
found
to
be
in
a worn
condition
it is
advisable
to
■t
a
Service crankshaft,
complete with
main
and big-end
bearings,
as
supplied
by the
Factory.
Both the
big~end
and
main
bearing
liners
are
located
in
the
bearing housings
by
a
small
tag
on one
side of
each
half-bearing;
it
should
be
noted
that
the
bearings
are
fitted
so
that the
tags
come on
the
same
joint edge of the
bearing
housing,
although
on
opposite
corners.
To detach
the big-end
bearings,
bend down
the
locking
strips
so
that
the
bolts
may
be
removed.
Remove
the
connecting rod
caps
and
extract
the
bearings.
Care should
be taken
to
see
that
the bearing
journals
are
thoroughly
cleaned before
installing
new
bearings.
No
scraping is
required,
as
the
bearings
are
machined
to
give
the
correct
diametrical
clearance
of
.0016
in.
(.04
mm.).
IA.16
.a"
Main bearings
Remove
the
engine
from
the
car
and
remove
the ■ywheel
and clutch,
the
timing chain (Section
A.lO),
the
sump
and
strainer
(Section
A]
l)
and the
rear
engine
mounting plate.
Note
that
a
thrust
washer
is
fitted
on
each
side of
the
centre main
bearing
to
take
the
crankshaft
end-thrust.
These
thrust
washers
each
consist
of
two
semi-circular
halves,
one
having
a
lug
which
is
located
in
a recess
in
the
detachable
half
of the
bearing
and the
other
being
plain.
Before
re■tting
the
crankshaft
check
the
end-■oat
(see
‘GENERAL
DATA’)
and
select
and ■t
new
upper
and
lower
thrust
washers
as
required. The
washers
are
available
in standard
thickness
and
.003
in.
(.076
mm.)
oversize.
Remove
the
two
bolts
and locking
plate
securing
the front
main
bearing
cap
to
the
engine
front
bearer
plate.
Remove
the
main
bearing
cap
retaining
nuts
and locking
plates
(early
engines)
or
the
self-locking
nuts
and plain
washers (later
engines).
When ■tting
new
bearings
no
scraping
is
required
as
the
bearings
are
machined
to
give
the
correct
diametrical
clearance
of
.001
to
.0027
in.
(.025
to
.067 mm.).
In the
case
of
a
‘run’
bearing
it
is
always
essential
to
clean
out
thoroughly
all
the
oilways
in
the
crankshaft
and block,
wash
out
the
engine
sump
with
paraf■n (kerosene),
and
clean
the
oil
pump
and
sump
strainer
to
ensure
that
no
particles of
metal
are
left
anywhere
in
the
lubricating
system.
The
rear
main
bearing
cap
horizontal
joint
surfaces
should
be
thoroughly
cleaned
and
lightly
covered
with
Hylomar
J
ointing Compound
before
the
cap
is
fitted
to
the
cylinder
block.
This
will
ensure
a
perfect
oil
seal
when
the
cap
is
bolted
down
to
the
block.
Re■t
each
main
bearing
and
cap,
re■tting
the
thrust
washers
in their
correct
positions
at
the
centre
main
bearing
with
the
oil
grooves
away
from
the
bearing.
The
connecting
rod big-end
bearing
locating
tags
(A)
and
grooves
(B). The
figures
(C) indicate
the
cylinder
from
which
the
rod
and
cap were
removed
MGB.
Issue3.
1329

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English