340 Gets Terrible Gas Mileage

Hey guys, brand new to the forum. I just recently (about 30 days ago) bought a 1973 Dart Sport 340. It has a 340 with a performance cam, Edelbrock 650 4 barrel carb, headers with the Torqueflite automatic transmission. The first couple of tanks look like I am getting a little over 6 miles per gallon. This is all city driving but surely I should be getting much better gas mileage.

I'd appreciate comments on what mpg you think I should be getting and where should I start in trying to improve this.

Thanks

Dave

there is something really wrong. What state do you live in?