This port on the Rochester 2 Jet is typically covered with a clean out plug so many people miss it. "It is an emissions device. My perception is that it was installed to limit the amount of fuel going to the main metering circuit so that, even if jet size was increased, the actual volume of fuel could not exceed the original jet specs.

Presumably, they did not expect that any of us might be smart enough to look under the "funny-lookin' plug" and back it out a little more, or remove it entirely." ~Jeff Dreibus @ The Old Carb Doctor; Nebo, NC.

We don't have manufacturer specs on this little adjustment needle and recommend you leave it alone, otherwise it'll take some trial and error to get it back in shape.