MODELS 2G-2GC-2GV PAGE 30

Delco

the diaphragm to return to its normal position under spring tension, thereby closing the throttle valves on both end carburetors. The two end carburetors feed fuel and air any time the throttle valves in the center carburetor are opened approximately 60 degrees or more, except during the engine warm-up period.

Service procedures are similar to those described previously. Refer to the "D" Section of the 9X Parts and Service Manual for all adjustment procedures and specifications.

THERMO-LOCKOUT VALVE (Fig. 52)

The choke operates basically the same as the choke on the standard 2-bore carburetor. However, there is a lockout lever located on the front carburetor connected to the choke shaft by a rod. This lockout lever automatically keeps the front and rear carburetors out of operation by locking the throttle valves closed until the engine is thoroughly warm.

CARBURETOR SYSTEMS

All six basic operating systems described previously are used in the center carburetor, while secondary carburetors (front and rear) have only float, main metering and accelerating pump systems.

FIGURE 52

The systems are identical in operation on all three 2-bore carburetor installations except that calibration differences will vary between engine applications.

A temperature controlled valve is used on some applications, in place of the choke lockout linkage, to keep the end carburetors out of operation during the engine warmup period. The valve controlled by engine water temperature shuts off all vacuum applied to the vacuum switch on the center carburetor, until the engine is thoroughly warmed up.

SERVICE

On some three two-barrel carburetor installations the vacuum diaphragm is mounted on the rear carburetor and is connected to the rear carburetor throttle lever by a link. The choke lockout lever is also mounted on the rear carburetor and is connected to the center carburetor choke valve by the lockout rod.

When the engine temperature reaches approximately 145° F the temperature controlled vacuum valve opens, allowing vacuum to be applied to the vacuum switch. The vacuum switch on the center carburetor operates in the normal manner. It opens at approximately 60 degrees of primary throttle travel, applying vacuum to the diaphragm on the front carburetor, which in turn opens both end carburetor throttle valves.

The operation of this type installation is identical with the standard unit previously described. The only differences are in the vacuum diaphragm and choke lockout adjustments which are made on the rear carburetor, instead of the front carburetor.

CARBURETOR TOOLS AND GAUGES ARE AVAILABLE THROUGH UNITED DELCO DISTRIBUTORS

ADJUSTMENT PROCEDURES AND SPECIFICATIONS

Refer to the Delco Carburetor 9X Manual "C" Section for Replacement Parts and "D" Section for Trouble Shooting, Adjustment Procedures and Specifications, for each carburetor model. The adjustments should be performed in sequence listed as applicable to each carburetor model.

The 9X Manual, Carburetor Tools and Gauges, are available through United Delco Suppliers.