Slant 6 Gas Mileage

Well not sure what to add. But are you sure you are figuring it correct? Are your brakes dragging? What kind of numbers did you get before the rebuild? Drove mine 350 to Rod Run in Pigon Froge TN last year and got 23mpg. stock bottom end, Holley 4bbl with a header. 3.73 gears in an 8 1/4 rear, with the A/C used part time.