Gas Mileage query Holley 318

What do you folks down there have for alky in the gas? Alky reduces mileage because it takes more of it to properly burn. What do you have for a camshaft? HUGE difference

Any idea on your head/ piston combo? Very low compression ratio is not going to help.

And with others, play with timing and jetting. Look at the plugs. "If you are serious" you might consider a wide band O2 setup which last I knew were around $200 US

"Back in the day" a stock B body 318 single exhaust say, 67--70 ish year could pull 18-20 mpg if driven carefully

I swapped a 71 (hi compression) stock 340 into my 70 RR around ?73? and that thing got 17 with headers, 3.54 Dana, 4 speed