Some Rochester 2 barrel carburetors use a check ball at the bottom of the accelerator pump well and some don't. This video will explain how you can tell if your carburetor needs the check ball. Don't assume because your check ball was missing that it doesn't need one. The previous re-builder may have left it out, or perhaps it fell out when you were taking the carburetor apart and you didn't notice.
The smaller, aluminum check ball resides at the bottom of the accelerator pump well. The bigger stainless steel check ball goes in the main discharge. There is one kit that has the aluminum check ball as the bigger ball. In this case the bigger ball would go in the accelerator pump well.
https://youtu.be/6U7QW4kYLcM?si=RWa5NJZYzczljrbL
Not a problem. Turn the carburetor over and while heating the outside area of where the check ball resides tap the float bowl on your work bench. Don't over heat so much you melt the bowl. The ball should come out.
This is usually caused by someone putting the large check ball in the pump well instead of the smaller aluminum check ball.
Using a check ball the same size (but stainless steel), put it in the hole and tap it using a brass drift punch to make the hole form to the check ball.
**90-158: 3/16" Steel** in the main discharge
**90-20: 5/32" Aluminum** in the bottom of the pump well