Saab 95 1967, Service Manual

Page: 97 / 610

Starting automatics
plate gradually opens and is wide ope
of approx. 140°F (60°C).
The starting automatics feature a vacuum-regulated piston
which, via a lever, open the choke plate slightly as soon
as the engine has started, thus providin
air and preventing "suffocation".
Furtermore, there is a mechanical device which forces
the choke plate to open, then the vacuum falls due to
remarkable acceleration.
The starting automatics include a step cam chich serves
to increase the idling speed when starting from cold. In
order to engage the fast idle device when starting from
cold, the accelerator pedal must be pressed right down
and then released before an attempt to start is made. This
is necessary in order to release the step cam thus enabling
the latter to take up the position decided by the thermo-
static spring.
The position of the throttle valve is then not governed
by the idling screw any longer but by the position the
stop on the step cam.
n at a temperature
9 sufficient engine
Automatic choke (Modulating choke) as from carburetor
71 TW—JD
USA cars as from carburetor 70 TW—AA
The choke flap is regulated in the same manner as before
by a bimetal spring which reacts to the coolant tempera-
ture.
When the engine is started, a vacuum-actuated piston is
drawn downwards in a cylinder bore and, if the engine is
cold, the choke flap opens somewhat. This is done by a
lever and is necessary in order to supply the engine with
enough air so that it will not "suffocate". The new design
differs from the old one in that there are two slots along
the bore of the cylinder. When the piston descends about
3 mm (0.12”) the inner slot is exposed above the top of
the piston, and when the latter descends a further 4 mm
(0.16") the outer slot is also exposed. Atmospheric air
can then flow through the slots to relieve the vacuum on
the underside of the piston, so that the position of the
choke flap is adjusted to the load on the engine. In the
older type the choke flap opens by about 4.5—5 mm
(0.18—0.20”) with the piston all the way down. The new
type has a longer cylinder bore, so that the choke flap is
wide open when the piston is all the way down.
STARTING
AUTOMATICS
1. Thermostatic spring
2. Vacuum piston
3. Lever .
4. Thermostatic spring lever
5. Vacuum 9855593
6. Fast idle nap dog
7. Step cam
8. Link rod
9. Choke plate shaft
10. Choke plate
200-15