Hey yall I just became the owner of a 64 chevy step side 1/2 ton short bed with 230 cid. I am in the process of rebuilding the carb. I is a Rochester bv with manual choke. my questions are, what is the idle vent valve for, what is its purpose, and how do I adjust it. I was under the understanding it has something to do with and automatic choke but beings as I am well lets just say an idiot when it comes to carburetors I need help.