Classic/Antique Car Repair: Fuel mileage-Quadrajet, chevy c, fuel mileage

Question
I have a 84 Chevy C-20 PU with 1978 350 eng, with quadrajet carb.
Seems to run good but cant get over 10 mpg no matter what I've tried. What can I do to increase mileage? I'm open to anything that works. Thank in advance for your time and help

Answer
10 miles per gallon for a C 20 is not bad mileage. Before assaulting the carburetor check the rear end gears. If there is a tag on the rear end that will make it easy if there is no tag connect a tach to the engine and check the RPM at 60 miles per hour in high gear. Let me know and we will go from there. Also what size and type tire do you have?
Brad