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THE ENGINE
A
Fig.
A
.S
Withdrawing a
tappet
with
a •·al•·e
grinding suction
tool. The
adjusting
shim
b Indicated
by the arrow
Section A.19
VALVE
TIMING-CHECKING
AND
ADJUSTING
Eltcessive
stretch in the timing chain or variations in
~ ~p~t
c:leara.nccs "'ill
have a con.sidemble effect on
tbe
valve
timing and cause the performance of
the
car
to
ruft'er. The valve timing should
thc.
r efore be checked
at
regular intervals and adjusted
if
necessary.
Fig.
A.6
The use of a dial indical()r
to
clreck the
ro/w:
liming.
The indicator
needle
has mo'Wd in an anti-elockwbt:
direction, showing a total tappet displa«mt:nt
of
·074
in.
(1·882
mm.)
in
this example
l>IGA
(Twin Cam).
Issue
4
27765
Proceed
as
follows.
Remove
the
c:amshoft
covers and check the tappet
clearances as
detailed in
Section
A
.
IS;
adjust
them if
necessary.
Mount a
dial indicator
to a
suitable fixed point on the
cylinder
head
with the
mdi~tor
foot
resting
on
No.
I
inlet valve tappet.
Make
certain that the
cam
is clear of
the tappet and
set
the dial indicator to
'0'.
Tum the engine
until No.
I
piston is
at
T.D.C.
with the valves rocking
(i.e. No. 4 piston at
T .D.C.
on compression stroke)
aDd
line
up
the notch
in
the
cranlcshafi pulley
with
the
pro-
jection
in
the
timing
cover
(see
Fig.
A.
7).
If the
timing
of
the
inlet
camshaft is
correct
the
dial
indicator
will show
that the
tappet
has moved
between
-on
and -o83 in.
(1·831
and 2-108 mm.) (see Fig. A.6).
Fig. A
.1
When the groou in the crankshaft pu/lry coincldu
with the small projection on the timing
case
Nos.
I
and
4
pisto111 au
Ill
T.D.C
Transfer the dial indicator to No. I exhaust
tappet
without moving the engine from T.D.C.
aDd set
the dial
indicator
to '0'. Tum the engine until the tappet has
risen fully
(until
the
cam
is
clear
of
the tappet) and check
the displacement.
This
should be within
the
tolerance
shown
above for the
inlet
tappet.
If
the timing
is incorrect it
can
be reset in the following
manner.
Remove
the
timing chain co'-er as detailed in Section
A.21. Knock
back
the
tab washer
on
the
chain
adjuster
securing bolts and
remo\·e
the chain
adjuster. Swing the
adjuster
sprocket fork
clear
of
the timing
chain.
Turn the camshafts until the slots
in the
inner
flanges
line up with
the slou
in
the
front
camshaft bearing
housings. If
the t
iming
chain has been
removed
make
certain
that
the pistons are half-way down the bores,
otherwise
there
is
danger
of
the valves
fouling
the piston
A
.9
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