During a search, I found the following comment on Rochester B's at this
Land Rover website :
"There is a pressure valve inside the carburetor body that consists of a steel ball and a spring. There is a metal rod across the top of the opening to keep the parts in place. A rebuild kit comes with a new ball and spring. Be advised that the spring rate is different than the original and replacing it can cause problems. Leave this pressure valve alone if you can when rebuilding the carburetor If you need to open up the passage reuse the old spring."
I don't know if it will help anyone, but more info. never hurts.
