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Rochester B, BC, BV Carburetor Check Ball Placement

Rochester B Check BallThe Rochester 1 barrel carburetor (B, BC, or BV) can use either 1 or 2 check balls.

This particular carburetor only uses 1 check ball. There is only 1 hole in the pump well (A). This is the discharge hole. Gas is fed by running over the rib (B) into the well.

Some 1 barrel’s require 2 check balls. These will have 2 holes at the bottom of the well. 1 for fuel entry and 1 for discharging. This type will use an aluminum check ball inside and in the bottom of the well.

The main discharge is (C). This is where the fuel discharges when the accelerator pump is pushed down, accelerating.

Also, at the main discharge (C), the bigger steal check ball sits at the bottom of the hole. The spring and T go above it.

The aluminum ball sits at the bottom of the well, at least the models that use it. When the pump is pushed down, the pressure of the pump holds the ball down and forces the fuel out the exhaust hole into the main discharge. There cannot be anything holding the ball down, or it wouldn’t allow the fuel to fill when the pump is rising. If the fuel is feeding back into the well, then the check ball isn’t sealing. It should be the aluminum ball. Tap the ball lightly with a brass punch to seat it. If by chance the ball is coming out of the hole completely, then look at the return spring to see if it is keeping the ball from coming out. You may have to spread the bottom of the spring out to fit better.
Some of the B’s have the intake ball on the bottom of the float bowl next to the well. A screen fits over the ball. Again it cannot be held down.
Rochester 1 Barrel Parts
Updated on 12/09/2020

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