Resurrecting Mom's Duster

12 has been the best so far. I’m usually getting 8-10. But to be honest Ive never got the cruise AFR squared away with the Edelbrock.
sweet, thanks. that gives me a rough starting point then. I'll be running EFI so i should get a bit better. But i'll figure it for 12 mpg. I'm not running a spare tire so I have plenty of room for whatever size. Right now, I have a 38 gallon tank from an 84 Ram 350 van shoved up in place and its HUGE but fits.