Posted by Mike on 2/18/2013 to Rochester 4G
The Rochester 4 Jet carburetor has two check balls. One (the bigger) check ball is installed in the main discharge. The main discharge check ball is used to plug the discharge when the engine is not accelerating, otherwise the vacuum from the engine will draw fuel through the discharge causing a rich situation.
The 2nd, or other check ball is placed in the bottom of the accelerator pump well. This one is used to plug off the pump well when accelerating. If this check ball was missing, the fuel would simply bleed back into the float bowl instead of going out the main discharge.
Which Check Ball
Your kit will have 2 check balls. The aluminum, or smaller check ball should be at the bottom of the accelerator pump well. The larger check ball will go in the main discharge hole. The spring and T goes above the check ball. The spring simply puts a bit of pressure on the check ball, so it stays shut until there is some fuel pressure pushing it up.
The Check Ball is Stuck
A check ball will get stuck in the accelerator pump well for a couple of reasons. The carburetor may have been sitting for an extended period of time and corrosion may have set in. The other possibility is that the wrong size check ball was put in the wrong hole. The smaller (and sometimes aluminum) check ball goes in the accelerator pump well. The bigger ball resides in the main discharge.
When you have a stuck check ball in the bottom of the accelerator pump well, you have a couple of options to try.
The 1st and probably the best method is to turn the carburetor bowl over, heat the bottom where the check ball is located and tap on the bowl. The ball will most likely come out. Be CAREFUL you don't get the metal too hot. Pot metal in a carburetor will puddle up very quickly and you also don't want to distort the trough where the check ball sits.
The 2nd method is to drill a hole in the bottom of the carburetor opposite to where the check ball is. Drill only big enough so that you can get a stiff wire through to poke the ball out. When done patch the hole with a small amount of JB Weld. Try not to get any in the well, or you may partially plug the accelerator pump circuit. The trick to this method is to locate your hole exactly opposite of the check ball hole.