MODEL 859 CARBURETOR -Updraft

CHAPTER IV

A. DESCRIPTION 1. DESIGN

The Holley carburetor model 859 is a single barrel updraft carburetor with a side air inlet. It is designed for engines where overhead space is limited, as in the Ford six cylinder cab-over-engine truck. This carburetor contains many of the same engineering features found in the Holley downdraft units. The main fuel flow is metered by a fixed jet which has been individually flow tested to insure proper calibration of the carburetor. The added fuel for high power output is delivered by a fully automatic vacuum piston type of power enrichment system. The accelerating pump incorporates a spring over-riding feature to prolong the discharge of fuel for smoother acceleration. The carburetor is fully sealed and balanced. All air bleeds and vents are supplied with filtered air from the air cleaner, giving added protection against the accumulation of foreign matter in these passages. The float chamber is vented to the carburetor air inlet, maintaining balanced air pressures in the carburetor to assure proper fuel metering. A sump and a drain plug at the bottom of the float chamber simplify the removal of any water which may condense in the fuel tank and enter the carburetor. This carburetor also contains interconnected passages which produce a balanced vacuum for control of the spark advance of a Holley pressure distributor.

2. APPLICATIONS

This carburetor model is manufactured in two sizes, the 859-FS series and the 859-H series. The smaller 859-FS series

used on the Ford 226 cubic inch six cylinder F-5 C.O.E. truck engine has a 1-732 inch venturi and a standard two bolt 1-1/4 inch S.A.E. mounting flange with a 1-916 inch throttle bore. The larger 859-H series used on the Ford 254 cubic inch six cylinder F-6 C.O.E. truck engine has a 1-1/4 inch venturi and a standard two bolt 1-1/2 inch S.A.E. mounting flange with a 1-1116 inch throttle bore. Since these carburetors are alike in design, both the 859-FS series and the 859-H series will be included in this chapter.

Note;   The list numbers of carburetors applicable to each vehicle (model and year) may be found in the current Holley Carburetor Parts Catalog - Ford, Mercury, and Lincoln division. (Section II, Division C.) 3.   MAJOR SUBASSEMBLIES

Model 859 carburetors are composed of two major subassemblies; the upper body assembly and the lower body assembly. The cast iron upper body contains the throttle plate, idle speed and mixture adjusting screws, a removable venturi, and the fuel inlet valve which is operated by twin floats suspended from the upper body. The die cast lower body contains the removable fuel metering parts, the float chamber, the accelerating pump, and the carburetor air inlet with a manually operated choke plate.

4.   LINKAGES, LEVERS, ETC.

The linkages and levers on this model are designed to function smoothly and with a minimum of wear. The throttle lever has

a ball and socket type connection to the ac-