what is the best MPG can you probably get outta a 350 small block for a daily driver? I heard compression ratio is a factor 2 get better gas mileage. what can probably get on mpg, thnx.  

There are man questions that we could have to ask for us to tell you what potential gas mileage you could get. What kind of transmission, how many speeds, rear end ratio, carb or fuel injection, compression ratio, ignition system, right about of carb for engine, headers or stock exhaust, do you have smog and/or air conditioning on your car, weight of the car, tire size, all these questions would need to be answered for us to give you suggestions on how to make it more fuel efficient if at all possible.  

going to a higher compression negates the use of cheep pump fuel....

first is to invest in a fuel mixture display.. they are under 50 bucks to start for simple ones... plus the sensor and bung installation...

if you are building a motor...  cam selection...  over the years i have built a bunch of motors.. and found that a reground cam with the H230 grind on it.. is about best...i have used that grind in a bunch of different motors... and everybody was happy... one guy i swapped out a big rv grind.. H131  and put in the H230 and the E150 /351w went from 11 mpg to 17...  and the van would keep up with traffic... rv cams were designed when 55 was the max speed...  above 55 they run out of power...

most cam grinders will know of the H230 grind..  it has been around for years...