The throttle plates in each carburetter are on a common spindle and the synchronising
linkage between the corburetters ensures that the throttle plates in each carburetter
open an identical amount. It should be remembered that
one barrel supplies one
cylinder only, since the inlet tracts are not interconnected. Apart from the throttle
linkage, the carburetters are identical, and each carburetter
is,
in effect, two
carburetters with duplicated main jets, idling jets, etc.
However,
whilst each barrel has an accelerator pump jet, there
is
only one diaphragm
type accelerator pump per carburetter, and
this feeds both jets. To facilitate cold
storting a progressive starting device is fitted, discharging mixture into both barrels
on the engine side of the throttle plates.
The
idling jets, main and air correction
jets, together with their emulsion tubes, are accessible after removing the small
rectangular cover secured with screws to the top of the
flwt chamber cover.
A
common flwt chamber
is
incorporated in each carburetter with twirl floats, to
reduce the effects
of fuel surge, actuating o single needle valve which incorporated
o damping device to prevent the needle from chattering on its
seat. The
floolh
straddle the centrally located jets, their position reducing the effects of the fuel
surge which occurs when cornering, braking and accelerating.
A
gauze filter is
fitted between the fuei entry point in the carburetter cover and the
flwt
chamber.
The followin
g
operating details apply, for simplification purposes, to one barrel
of
a
carburetter. The supply to the other barrel
is
the same.
Fuel
from
the tank is delivered to the banio,
(2)
then through the fllter
(1)
to
the
flout
chamber, via fhe needle valve
(15)
and its seat
(14).
The fuel level
k
detenlned by the
flwt
(17).
The float chamber
is
vented to the atmosphere at
(4).
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