Originally posted by lt1s10
the big tube is a vent that goes to the charcoal canister for the gas vapors. it looks like to me the choke is open, if not the spring in the choke housing reg. it. i think you are taking a pic of the secondary butterflys. the choke butterfly is the small one at the top of the carb. the big betterflys are spring loaded and opens according how much air is pulled across them when you open the carb all the way up.
i went back and looked that is a manual choke on that carb, and the only rod you would need to make it work is on there, its the little rod going up to the butterflys.