493646083 Carburetor

4. CARBURETOR





4-1.
Description
94

4-2.

Carburetor Specifications

94

4-3.

Carburetor Operation

96

4-4.

Inspecting and Adjusting

97
4-1. Description

The carburetor, serving all four cylinders, is of a horizontal-draft Solex type, composed of the following components parts:



Fig. 4-1


4-2. Carburetor Specifications

Item
Specifications
Venturi diameter
Main jet
Main air hole
Slowjet
Slow air jet
24 mm (0.945 in.)
# 105
0.5
# 57.5
1.6
4-3. Carburetor Operation

Float chamber
The float chamber with its needle valve is a vessel receiving the fuel from the fuel pump and holding it up to a certain constant level. The float responds to the up and down movement of fuel surface and actuates
the needle valve.

Slow speed mixture
Referring to Fig. 4 2, fuel flows out of the floatchamber through main jet and reaches slow jet. Slow air jet admits an, metering this air and sends it to the inlet side of slow jet, which meters this mixture of fuel and air into the slow circuit terminating at idle port and bypass port. These two ports open out 10 the main bore, near throttle value.
During idling, the slow speed mixture (coming from slow jet) is sprayed out mainly from idle portand becomes mixed with the air flowing into the main bore. Thus, the air fuel mixture can be made richer or leaner by resetting idle mixture adjusting screw in loosening or lightening direction, respectively, in that order.

High speed mixture
Two circuits come into operation for producing the high speed mixture. One circuit begins with main jet, which meters out fuel from the float chamber. Thisfuel is mixed with the air meteringly admitted by main air hole; this mixing is effected in emulsion tube, The emulsified mixture is then sprayed out into the venturi from main bleed pipe.
The other circuit goes into service when the manifold vacuum falls to mow the diaphragm in the enrich- ment device below the float chamber. As the diaphragm so moves, the valve above it opens to let out fuelthrough the hole provided in the chamber bottom. Enrichment jet meters out this fuel and sends it 10 emulsion tube. From which it flows into main bleed pipe and is sprayed into the venturi.

Acceleration power system
The main device of Titus system is an accelerating pump for making the carburetor respond without delay to the accelerator pedal depressed abruptly while the engine is running in its lowspeed range or is idling. The actuating lever of this pump is linked to the throttle shaft so that, as throttle valve opens quickly, the pump lever pushes up the diaphragm, thereby closing suction ball valve and opening discharge ball valve. Consequently, the fuel in the pump is forced out of pump nozzle into the venturi.

4-4. Inspecting and Adjusting

Jets
Wash the jets clean. Wash the holesin which jets are located, and clear each hole by directing compressed air to it. thereby removing foreign matter, if any.
A clogged slow jet is usually responsible for erratic engine idling. Erratic engine operation in the medium and high-speed ranges and during acceleration is often accounted for by a clogged condition of main jet, main air hole or hole constrictions in the carburetor body.Fig. 4-3

Needle valve
The conical up of needle valve is subject to wear as this tip seats and unseats in the normal operation of the needle valve. When the needle valve is in closed condition. This tip is pushed against the seat by the float.

Inspect the conical tip and seal for evidence of clogging. As necessary, remove the seat and wash it clean. A worn needle, illustrated in Fig.
4-4,must be replaced. Remember, a clogged or poorly seating needle valve is usually account
table for “overflow”.

Fig. 4-4

Choke valve
Cheek to he sure that. when the choke knob is pulled out all the way, the shaft of choke valve in
the carburetor will rotate, and that, when the knob
is pushed in, the shaft will rotate back to original position.



Fig. 4-5 Choke valve (with knob pulled out...