Have a question for those of you who might know. On my '27 Coupe there is a rod going from inside the cab to the carb bowl. I originally thought that this was a petcock and turned fuel on for the carb. But after fooling with it I found out it actually affects how the engine runs. Is this a fuel mixture valve also. If I shut it off of course no fuel get's to the carb but if I open it to much the engine acts as if it's flooding. About half way is where it runs the best.
It's the adjustment for the main jet, you find it on all T's. Seems like you've got the adjustment about right - While running on a straight road at even speed screw it in to lean until it runs bad, open it up until it again runs bad, then turn back to the mid point in between
When starting on a cold day you may open the carb adjustment a little - when the engine has warmed up some you can return it to the usual setting.
When travelling in the mountains differing heights may also cause a need for adjustments of this rod that controls a needle in the carb.