Hi,
I'm in the middle of carb rebuild, and using the online Rochester B manual as a guide. Check out the page that shows a pump screen and retaining clip being installed:
http://chevy.tocmp.com/booklets/5020mts15.htm My carb does not seem to have this feature. It is off a 216 from a '51 3600. I note that my carb actually is the odd Rochester "C" that was discussed elsewhere on Stovebolt. Is it possible this feature was left off?