[blue4X4]

Sounds about right for what you have. I get about 16-17 gallons, about $35-40.00 a tank and lasts about a week at 17mpg in my 350. You would have to reduce gear ratio, weight, Cubic inches, compression ratio, TBI size, Fuel flow, usually manual transmissions get better milage but hard on the leg around town a lot. Could change over to Diesel fuel. Nothing would help much that wouldnt be costly and something you dont want to sacrifice.

I had a 66 chevelle I customised with a 408ci BB Chevy and tunnel ram w/4.11 gears that got about 8 miles a gallon on Cam 2 fuel. Big motors with big gears get little fuel milage-just the way it is! sorry, I wasnt much help, but if you want better milage you have to give up something a little bit anyway. I would go with some 3.73 gears and next time you buy tires get bigger diameter tread. Some of the other guys in here may know what to change to reduce fuel flow into the TBI. Good Luck!