My Holley 1945 carburetor for my 1986 D150 with the slant six engine does not have a pump discharge weight or ball. Is it supposed to have these parts? The shop manual shows these parts for the carb. What would happen without these parts? I can't find any replacement parts online. Does someone know where I can get them?

Also I have a problem that sometimes when I start the truck it won't idle. It will rev up but has a very rough idle and eventually stalls. The fix is to remove the needle valve and reinstall it. I have replaced the needle valve several times with new parts and yet the problem continues. Any ideas as to what is wrong? There never is any debris in the needle valve. It is if the slow running circuit is blocked, the floats are sticking or the needle valve is sticking. Again, this only happens occasionally.