What carburetor is shown in these diagrams?

The YFA 1-V carburetor, shown in both non-feedback (Fig. 4.1) and feedback (Fig. 4.2) versions, as used on various in-line six-cylinder models, viewed from the left side.

Where are the idle adjustment screws on the YFA 1-V carburetor?

Both figures label a fast idle adjusting screw near the throttle lever/linkage area and a curb idle adjusting (adjuster) screw located below it on the left side of the carburetor.

How can I tell a feedback YFA carburetor from a non-feedback one?

Per Fig. 4.2, the feedback model has a feedback or altitude solenoid with a wiring pigtail, an A/C throttle solenoid, and a choke pull-down diaphragm; the non-feedback unit in Fig. 4.1 lacks these callouts and instead shows the automatic choke with hot air choke inlet.

What are the high step and kickdown step shown in the inset?

They are positions on the fast idle cam; the inset in Fig. 4.1 shows the fast idle adjusting screw resting against the cam, identifying the high step and kickdown step positions.

What is the EGR wide open throttle dump valve?

It is a component labeled on the lower left side of both YFA 1-V carburetors, called the 'EGR wide open throttle dump valve' in Fig. 4.1 and 'EGR wide open throttle (WOT) dump valve' in Fig. 4.2.

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YFA 1-V Carburetor Diagrams - Feedback & Non-Feedback, Inline Six (Ford Bronco)

Manual page with labeled photos of YFA carburetor showing component callouts

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Service manual page showing labeled photographs of YFA 1-V carburetors with callouts to chokes, levers and adjusting screws.

AI caption September 2010 · Photo 24 of 108

This is page 142 of a printed automotive repair manual showing two labeled illustrations of the Carter/Motorcraft YFA 1-V (one-venturi) carburetor used on various in-line six-cylinder models. Figure 4.1 depicts the non-feedback version of the carburetor viewed from the left side, with callouts identifying the air cleaner bracket, tamper-proof riveted choke cap, hot air choke inlet, automatic choke, fast idle cam (with an inset detail showing the high step and kickdown step of the cam and the fast idle adjusting screw), cam link, throttle lever, fast idle adjusting screw, curb idle adjusting screw, bowl vent tube, and EGR wide open throttle dump valve. Figure 4.2 shows the feedback model of the same YFA 1-V carburetor, also from the left side, identifying the A/C throttle solenoid, tamperproof riveted choke cap, cam link, bowl vent tube, choke pull-down diaphragm, fast idle adjusting screw, EGR wide open throttle (WOT) dump valve, feedback or altitude solenoid (shown with its wiring pigtail and connector), and curb idle adjuster screw. Both figures reference Section 2 of the manual chapter. The page is useful for identifying carburetor components, adjustment screw locations, and distinguishing feedback from non-feedback YFA carburetors on six-cylinder Ford trucks.

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Frequently asked questions

What carburetor is shown in these diagrams?: The YFA 1-V carburetor, shown in both non-feedback (Fig. 4.1) and feedback (Fig. 4.2) versions, as used on various in-line six-cylinder models, viewed from the left side.
Where are the idle adjustment screws on the YFA 1-V carburetor?: Both figures label a fast idle adjusting screw near the throttle lever/linkage area and a curb idle adjusting (adjuster) screw located below it on the left side of the carburetor.
How can I tell a feedback YFA carburetor from a non-feedback one?: Per Fig. 4.2, the feedback model has a feedback or altitude solenoid with a wiring pigtail, an A/C throttle solenoid, and a choke pull-down diaphragm; the non-feedback unit in Fig. 4.1 lacks these callouts and instead shows the automatic choke with hot air choke inlet.
What are the high step and kickdown step shown in the inset?: They are positions on the fast idle cam; the inset in Fig. 4.1 shows the fast idle adjusting screw resting against the cam, identifying the high step and kickdown step positions.
What is the EGR wide open throttle dump valve?: It is a component labeled on the lower left side of both YFA 1-V carburetors, called the 'EGR wide open throttle dump valve' in Fig. 4.1 and 'EGR wide open throttle (WOT) dump valve' in Fig. 4.2.