My 340 getting 6 mpg

Dana67Dart said
I drove 75 miles last Sunday and used 1/2 tank.

273 2bbl 3.23 gears 215 70 14 tires

3/4 of it was on the interstate at 75 mph
1/4 was on surface

Just over 9 mpg

And I get 18-19 with my 273-4 barrel with a 650 AFB and a 3.23 on the highway.