Hi,This is an old thread but if I could give my two cents.I have a '38 dodge w/the original eng.that has been upgraded to a 234 c.i. Have gotten as much as 32 m.p.g. while on a trip to Detroit to the Inliners conv. Av.25 on the entire trip. It has a 273 Camaro rear & a T-5 O/D trans. Turning around 2000 rpm @ 70 mph. It does 18 mpg in town & has a single b&b carb.You have to change something if you want less rpm & more mpg.Just finished a '51 ford coupe & av. 30.6 mpg on it on the trip to Tulsa...Good luck
