Page 71
214-28 Valve gear, B201 and B202
Setting the valve and crankshaft
When the pistons in No. 1 and No. 4 cylinders are
at top dead centre, the 0° mark on the flywheel
must be in line with the timing mark on the clutch
cover (or end plate if the clutch cover has been
removed).
When the timing marks on the camshafts are in
line with those on the bearing caps, the inlet and
exhaust valves for No. 1 and No. 4 cylinder are
i” closed.
Saab 900
Page 72
Valve gear, B201 and B202 214-29
As the valves open, they extend beyond the cylin-
der head and into the zone in which the pistons
move (combustion chamber). Consequently, an
alteration in the setting of the crankshaft and
valve gear may result in the valves and other vital
components in the engine being damaged.
The timing gear comprises sprockets and a
chain. The chain has two guides, one fixed and
one pivoting. The pivoting guide maintains the
tension in the chain, assisted by an hydraulic
chain tensioner.
The camshaft sprocket is guided by means of a
dog on the shaft. Each sprocket has 38 teeth and
is secured to the camshaft by a centre bolt.
The crankshaft sprocket incorporates a keyway
to locate it on the crankshaft. The sprocket,
which has 19 teeth, is secured by the centre nut
for the crankshaft pulley,
The chain is an endless, single chain with 126
links. The diameter of the rollers is 6.35mm
(0.25 in).
Page 73
214-30 Valve gear, B201 and B202
Removing the valve guides
(performed from above)
1 Before removing the valve guides, flush the
cylinder head with hot water.
2 Withdraw the valve guides using special tool
and pull rod 8393811, spacer 8393829
and nut 83 93 845.
Jackscrew
Pull rod
Spacer sleeve
Nut
OWN
1 Jackscrew
2 Pull rod
3 Spacer sieeve
4 Nut
5 Valve guide
To refit
1 Insert the valve guide from above and apply
the tool from below.
2 Before fitting the guides, flush the cylinde:
head with hot water and cool the guides by
immersing them in cold water.
Jackscrew
1
2 Pullrod
4 Stop
5 Nut
6 Valve guide
Saab 900
Page 74
Valve gear, B201 and B202 214-31
3 Fit the guides using special tool and pull rod
8393811, stop 8393837, 8390379 ana
nut 83 93 845,
4 Centre the tool in the valve seat and, using
the tool, draw the guide into its correct posi-
tion, as shown.
1 Jackscrew
2 Pull rod
3 Stop
4 Centring sleeve
5 Nut
6 Valve guide
Sa Run the 7.0-mm_ undersize reamer,
83 93944, through the guide.
b Follow up with the 7.0-mm H7 valve guide
reamer.
i Saab 900
Page 75
214-32 Valve gear, B201 and B202
Valve seats
For recutting the valve seats, use the cutter kit
comprising a T-wrench, pilot 83 93 928 and cut-
ters 8393936, Neway types 28645° and
27060°.
,
V)
Ss
Q
5
Valve seat angles for inlet and exhaust valve
seats: 45°.
Recutting angle: 60°.
Width of inlet valve seat: 1-1.5mm
(0.0394 -0.0591 in)
Width of exhaust valve seat: 1.25-1.75mm
(0.0492 - 0.0689 in)
(See drawing)
Inlet
Valves
Inlet valve face angle: 44.5°
Valve head diameter: 32 + 0.1mm
(1.26 + 0.004 in)
:
Exhaust valve face angle: 44.5° baie
(The contact surface of the valve hasa
0.006-mm (0.0002-in) coating of ste!lite.)
Valve head diameter: 29 + 0.1mm
(1.14 + 0.004 in}
i N.B.
Only a limited amount of material can be re-
moved from exhaust valve seats, since the stel-
i lite coating must be preserved as far as possible.
Consequently, if the valve seat is badly pitted,
the valve should be replaced.
Saab 900
Page 76
Valve gear, B201 and B202 214-33
Checking the valve clearance
(Cylinder head removed)
The valve clearance is checked relative to the
working range of the cam follower.
The checking values for the valve clearance are
19.5 + 0.05mm (0.77 = 0.002in) minimum,
and 20.5 + 0.05mm (0.81 + 0.002in)
maximum.
The setting values are 20.0mm (0.78in)
minimum, 20.4mm (0.80 in) maximum, with a
nominal value of 20.2 mm (0.79 in).
The valve clearance is equivalent to the distance
between the end of the valve stem and the cam-
shaft bearing seat. It is checked using tool
83 93 753 {measuring head).
Before the valve clearance can be checked, the
camshafts and cam followers must be removed
(see ‘Dismantling the valve gear earlier in the
section).
Check the valve clearance using tool 8393753
as follows.
Place the measuring head on two of the cam-
shaft bearing seats. Line up the instrument to
read the depth to the end of the valve stem.
Check that when the instrument is displaying the
maximum depth reading of 20.5mm (0.8in) it
actually reaches the end of the valve stem, which
will be confirmed by the fact that the measuring
head does not make contact with the bottom of
the bearing seat closest to the instrument.
Thereafter, check that the contact point of the in-
strument does not touch the end of the valve
stem when showing the minimum depth reading
of 19.5mm (0.77 in).
The valve clearance is correct when the reading
obtained is between the minimum and maximum
values.
Ifthe valve clearance deviates from the specified
checking values, adjustment must be made to
the valve stem or the valve seat: if the value is
lower than the minimum value then the length of
the valve must be reduced; if the value is greater
than the maximum value, then the valve seat
must be milled. The nominal value for adjusting
the position of the valve is 20.2 mm (0.79 in).
tt
fill
TTT
g Ten
708,
=
¥
Saab 900
Page 77
Timing chain, B201 and B202
Timing chain, B201 .......2.. 215-1 Timing chain,B202 ........,. 215-5
Timing chain, B201
M84 and earlier
CM CA: Engine No. E22812 and earlier
IM 1A: Engine No, E57339 and earlier
SM SA: Engine No. E57339 and earlier
The camshaft is driven by a single chain with a
mechanical chain tensioner and a straight chain
guide.
N.B.
Never rotate the crankshaft or the camshaft once
the timing chain has been detached.
A fully open valve can come into contact with a
piston at top dead centre.
To remove or refit the timing chain, the camshaft
and crankshafts must be lined up with their re-
spective timing marks (No. 1 cylinder at top dead
centre).
aiaei/ |
Page 78
215-2 Timing chain, B201 and B202
When removing or refitting the camshaft sproc-
ket, use tool 8393 357 to take the tension off
the chain.
Insert the hook as shown and pul! upwards to re-
lease the chain tensioner.
To fit the chain tensioner
After fitting the tensioner, set it by inserting the y
tool as shown, and rotating it to allow the ten- Wl
sioner to slide back against the chain.
Fit the camshaft sprocket and move the chain on
the sprocket teeth until the marks on the sproc-
ket and bearing cap coincide.
N.B.
The O° mark on the crankshaft must be in line
with the timing mark.
Fit the sprocket bolts compiete with plain
washers.
Warning
If the washers are omitted, the bolts wil!
foul the camshaft carrier,
for camshaft sprocket:
20 Nm (14.8 Ibf ft)
Page 79
Neen
Timing chain, B201 and B202 215-3
M84 onwards
CM CA: Engine No. E22813 onwards
IM IA: Engine No. E57340 onwards
SM SA: Engine No. E57340 onwards
The camshaft is driven by a single chain with a
mechanical chain tensioner, a pivoting guide
and a fixed chain guide.
N.B.
Never rotate the crankshaft or the camshaft once
the timing chain has been detached.
A fully open valve can come into contact with a
| piston at top dead centre.
To remove or refit the timing chain, the camshaft
and crankshafts must be lined up with their re-
spective timing marks (No. 1 cylinder at top dead
centre).
Page 80
215-4 Timing chain, B201 and B202
When removing or refitting the camshaft sproc-
ket, lock the chain in position by inserting the
handle of a suitable screwdriver between the two
parts of the chain as shown.
Resetting the chain tensioner
Press down the outside of the ratchet paw! on the
chain tensioner to render it inoperative. Push in
the chain tensioner by pressing on the chain
guide.
Retain the chain guide in this position, refit the
sprocket and chain and then release the chain
guide, whereupon the tensioner will press
against the chain.
To fit a new chain tensioner
1 Fit the newchain tensioner without removing
the transit lock.