MG MGB User Manual

THE ENGINE
A
f
‘
l
i
r
H
~A4874
Fig.
A.6
When fitting
valve
guides they
must
be
driven
in
until they
are
the required height
above
the machined surface of the
valve
spring
seating(A)
Grinding and
testing
valves
and
seatings
Each valve
must
be
cleaned thoroughly and carefully
examined for
pitting.
Valves
in
a
pitted condition should
be
refaced
with
a
suitable grinder
or new
valves
should
be
■tted.
Pitted
or uneven
valve
seats must
be
refaced
using
a
grinder
or
cutter,
care
being taken that only the
minimum
quantity
of
metal
necessary
to restore
the
seat
is
removed.
If
the
seats
are very worn
or
damaged refer
to
Section A28.
When
grinding
a
valve
onto
its seating
the
valve
face
should
be
smeared lightly with ■ne-
or
medium-grade
carborundum
paste
and then
lapped
in
with
a
suction
Pitted
valve
seats
should
be
re-faced,
usingServicetools, 18G
25,186
25
A,
18G
174 B,
18G
25
C, 18G 27,18G 28,180
28
A,
18G
28 B, 18G 28
C,
and 18G
174 D
MGB. Issue
7. 80619
grinder
(Service
tool 18G
29).
Avoid the
use
of
excessive
quantities
of
grinding
paste
and
see
that
it
remains
in
the
region
of the
valve
seating
only.
A
light
coil
spring
placed
under the
valve head
will
assist
considerably
in
the
process
of
grinding. The
valve should
be
ground
to
its
seat
with
a
semi-rotary
motion and
occasionally
allowed
to
rise
by
the
pressure
of
the light
coil
spring.
This
assists in spreading the
paste
evenly
over
the
valve
face
and
seat.
It
is
necessary
to
carry
out
the
grinding
operation
until
a
dull,
even,
mat
surface, free
from blemish,
is
produced
on
the
valve
seat
and valve face.
On
completion, the
valve
seat
and
ports
should
be cleaned
thoroughly
with
a rag
soaked
in
paraf■n
(kerosene),
dried,
and then
thoroughly
cleaned by
compressed
air.
The valves
should
be washed
in
paraf■n (kerosene)
and
all
traces
of
grinding
paste
removed.
Fit
a
new
valve packing
ring
when refitting
the
valves
(see
Fig. A.4).
Checking valve
timing
Set
No.
1
cylinder inlet
valve
to
.055
in.
(1.4
mm.)
clearance with the
engine
cold, and then
turn
the
engine
until the
valve
is
about
to
open.
Fig.
A.8
The
notch
in the pulley
approaching the
T.D.C.
position
for
pistons
1 and 4. The inset shows
the
timing scale
5°
marks
The
indicating notch
in
the ■ange
of the crankshaft
pulley
should then
be
opposite
the
longest of the three
pointers
on
the
timing
cover,
i.e.
the
valve
should
be about
to
open
at
T.D.C. and
No.
4
piston
will
be
at
T.D.C.
on
its
compression
stroke.
Do
not
omit
to
reset
the
inlet valve clearance
to
the
recommended clearance (see
‘GENERAL
DATA’)
when the
timing
check
has been completed.
The clearance
of
.055
in.
(1.4
mm.) is
necessary
to
bring the
opening position
of the
valve
to
T D.C. It is
not
possible
to
check
the valve
timing
accurately with the
normal
running
valve
clearance.
Adjusting valve rocker clearances
If
the
engine is
to
give its
best performance
and the
valves
are
to
retain
their
maximum
useful lifeit
is
essential
to
A9
_

MG MGB Specifications

General

Brand	MG
Model	MGB
Category	Automobile
Language	English