340 Gets Terrible Gas Mileage

Lean it out! Guarantee your rich. If you can smell it, It's wasted power. Fatten up the rods....easiest first step on the edelbrocks. I had a 351C in a 57 Fairlane. Erson Hi-Flow 2 cam, headers, Offy 360 intake, 3.5x 9 inch and a Predator PXP (?) Carb. I clocked 5 in town. That carb sucked on the street as it didn't have the street idle circuit of the PXi model. Put my Carter 600 back on and instant low end again and about 50% better mileage 7.5!