BALL AND BALL CARBURETORS: Model SV-33; Model SV-26; Model S-1;

This carburetor is termed a "two-stage, two-quality type' of carburetor. The following illustrations and text will explain its action and adjustments.
Operation: Through a given range of throttle-opening all the gas is drawn through the first-stage throttle at the top. The capacity of the first stage is sufficient to take care of all level road speeds up to approximately 40 or 45 miles per hour.
Fig. 1 shows how the second stage is brought into action by opening the main throttle (first-stage throttle, 1006) to its extreme position. The cam arm, integral with the main throttle shaft, coming into contact with the roller on the arm of the second-stage throttle shaft (to the left of M) causes the second-stage throttle to open under additional pressure (the spring (573) holds the second-stage throttle closed).
The resultant action is to draw an additional or secondary supply of gas mixture through the second-stage throttle through metering screw (H), through a nozzle to the right of (H).
Fig. 1 Amp the main or primary throttle closed. The dotted lines (Fig. 1) show the main throttle lever fully open and the cam arm (M) of main throttle shaft holding the second-stage throttle open.
Briefly speaking, the first stage furnishes all that is desired in what might be called the touring range, giving ideal economy and ample power for all ordinary purposes up to 40 or 45 miles per hour.
The secondary stage supplies everything desired over and above the first stage in the form of added acceleration, power, and speed.
Some of the features claimed for this carburetor by its manufacturer are as follows:
1. An automatic economizer or step-up, by means of which the mixture of fuel and air gives maximum economy when the car is running at constant speeds, and maximum power when accelerating, climbing hills, or pulling through heavy roads or sand.
2. A new idling arrangement, much easier to adjust, giving better idling, and very slow running.
3. A new and exclusive choke mechanism which gives an ideal mixture throughout the whole range of performance during the warming-up period in cold weather.
= Two-stage refers to the two distinct carburetors that arc foun4in every Ball & Ball carburetor; one, the primary carbu-
retor, is a small carburetor under the main throttle valve anti-operates under all conditions except closed main throttle. t i
The other, termed the second-stage, or high-sp4d carburetor, is an auxiliary carburetor which comes into action onl when the main throttle valve is opelted beyond approximately of its range.
Two-quality refers to the effect of the automalik economizer, or step-up on the primary carburetor mixture.
With the automatic economizer valve closed, the mixture is lean for economy. With the economizer valve open, the mixture is rich for power.
Idling Adjustment
The mixture for closed throttle running or idling is controlled by the idling adjusting screw (L). Screwing it in reduces the air, giving a richer mixture.
The arrow on the head of the screw usually points upward when the screw is turned all the way in. With the engine in good condition the proper adjustment should be obtained within one-quarter to three-quarters of a turn open from the closed position.
The best and most stable idle will be obtained with a mixture as rich as possible without rolling with the spark retarded.
If there is a weak cylinder or if the spark is too far advanced the engine will roll as with too rich an adjustment.
If after smooth running has been obtained by means of the adjusting screw the engine idles too fast, turn the stop screw (T) on the throttle lever to obtain the desired speed.
Fig. 1. Side view of Ball & Ball model SV-33 carburetor used on the Studebaker "Big Six."
Dotted lines show the main, or primary throttle lever wide open and earn arm (M) of main throttle lever holding the second-stage throttle open.

Metering Screws
As soon as the main throttle blade is opened wide enough to give.ft speed of 10–12 miles per hour, the idling adjustment's influence becomes nil.
Calibrated metering screws then control the quality of the mixtures, both in the primary and in the second stage respectively. Each metering screw carries a number of its head indicating the size of its orifice, larger numbers meaning richer mixtures.
. Another feature of this carburetor is the method of changing the setting for seasonal conditions. The fuel to the primary carburetor is metered by the screw at (B). This is interchangeable with an extra meterin screw placed in a lug cast on the primary air-her&at (P)

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Carburetor Manuals: Ball & Ball