Operation Of A.b. Valve; California Type A.i.s.; Emergency Air Relief Valve; Air Pump Air Cleaner - Datsun 620 Series 1977 Service Manual

The
non
California type operates
as
follows
secondary
air
is
sucked
through the air pump
air cleaner into
the air
pump
driven
by
the crank
pulley It is
then discharged through
the
check valve
to the
air
gallety where
it is distributed
to
each exhaust porL
The
secondary
air is then
injected
from
the
injection
nozzle
into
the
exhaust port
near
the exhaust valve
The
air
relief
valve opens
only
when
the
discharge
pressure
of
the air
pump
surpasses the
spring
force of
the air
relief valve during high speed
opera
tion When the air relief valve
opens
the
secondary air is discharged in
to
the
carburetor
air c1eaner
The
anti
backfire
valve
opens when
the intake manifold
vacuum
reaches
a
predetermined
value
during
decelera
tion
and permits fresh
air
to
now
into
the intake manifold from the air
cleaner
f
I
Jl
rn
l
I Air
pump
2 Air pump air
cleaner
3
Emergency
air relief valve
4
Air relief
valve
riu
Qj
j
I
@
Emission Control
System
To intake
manifold
The California
type includes in
addition
to
the
components of the
non
California
type
an
air
control
valve and
an
emergency
air relief valve
The
air
control
valve
opens
when
the
sum
of
the air pump
discharge
pressure and the intake
manifold
vacu
um applied
to the
diaphmgm
reaches
a
predetermined
level
and
discharges
the
secondary
air into the air cleaner
When
the pressure
becomes low
the
valve doses with the
spring
force
of
3
5 Air cleaner
6 Check valve
7
Air gallery
pipe
8
Carburetor
EC 13
To intake
manifold
Air
diSlcharge
to
intake manifold
Secondary
air
EC297
Fig
EC 23
Operation of
A B
lve
the air control valve
and
stops
dis
charging
the
secondary
air
F i g u r e
EC 25
When the intake manifold
vacuum
applied
to
the
diaphragm reaches
a
predetermined
level E A R valve
operates to
discharge
the secondary
air
into
the
atmosphere When the
pres
sure
becomes
high the valve closes
by
spring tension
of E
A
R valve
and
stops discharging the
secondary
air
fl
t
9 Air control valve
10
Injection
nozzle
II
Exha l
t manifold
12 Anti backfire valve
EC780
Fig EC
24
California type A I S