I'm guessing on my 71 bored 30 over, cam'd, other preformance acc.'s old 3 speed, and a stock 3.07 gear ratio I get about 12 in town

took it for its first road trip since the drivetrain restoration this weekend and got 12mpg through the 4 days. fuel injected, 350/350 with a 3.08 rear end

My old 402/th400/qjet/crane hmv-272 cam/4.1 rear/9.50x16.5 bias would get 10.5mpg around home and 13.5mpg highway@55mph, 3200lb slidein camper it would get 8.5-9.5mpg highway no head wind.
Since the rebuild same cam/engine combo but a new edelbrock 1411 carb and HEI, best sofar was 11mpg, average around home 9.5mpg, towing a 5500lb travel trailer around home 6.75mpg. Thinking of going back to the QJET.

Probbaly no better than 5mpg.

About 12 with a crate 350 th350 and 3:73 gears..

'69 K20, 350/265 Hi-Torque + Q-jet + stock ramshorns w/ dual exhaust + 33" tires + SM465 4-speed + 4:55's = 11mpg

Hence, the 50 gallon auxillary tank in the bed . . .

On our recent trip to Boykin Springs Park, about 64 miles each way, the truck got there on a quarter tank and we returned on another quarter. 128 miles on half a tank of gas, or I guess about 7.5 gallons of gas. 128 divided by 7.5 equals around 17.06 miles per gallon. The truck is totally stock from factory, 307 V-8, 2bbl carb, 3 speed column shift and no air. I was running 4 brand new tires and just had an alignment done as well.