My 340 getting 6 mpg

Miles are miles guys. My speedo not working is 100% irrelevant

You dont have to be a mathematician to know that I drove 81 miles combined. 62 yesterday and 19 today and my brand new fuel tank that is 18 gallons, (which i filled up completely full before my day out yesterday) my brand new fuel guage is saying my tank needs a refill speedo or not now im getting 5 miles to the gallon

Did i get on it a couple times. Well duh ! But i dont believe 1 or 2 pulls to 4500rpm can really affect your mpg that drastically

But we did suceed in getting the motor to make more power
Other than the carb and tune that you are already addressing, the cam overlap is where I would look for fuel consumption related to the engine.