Gas Mileage

[Robert5]

I consistently get 18 mpg on ethanol free 90 (usa) octane.
Now it's not a daily driver and no stop and go driving. I have gotten 20 mpg on occassion.
I am fairly gentle on the throttle.

[Go Fleiter]

my best result was 15,7 mpG (15 l/100km): only touring on quiet roads - no traffic - max. speed 56 mph..

I´m satisfied with more realistic + usual mix land/ city with  13,4 mpG (17,6 l/100km)

One exception: one complete tank emptied in only city traffic, lots of red traffic lights etc: 10,2 mpG (23 l/100km)

I don´t drive much Autobahn with speeds up to 85 mls/h and average 75 mls/h, but then I can see the tank needle fall...

With everythig greased, tires filled up and carb and ignition set well You do the optimum.
Greetings from düsseldorf!
Go

[TodFitch]

12 to 18 is the range I'd expect. You will have to have a very light foot on the accelerator to get near 18. If you floor it starting from lights and race up the the next light just to slam on the brakes you'll be closer to 12 or maybe even 10.

Also, speed kills gas mileage: Power needed to maintain a steady speed on level ground goes up as the cube of the speed. Double your speed from 30 MPH to 60 MPH and you'll need 8 times more power which translates into a lot more gas being used.

So, go light footed enjoying the back roads at yesterday's speeds and you can get 18 MPG. Drive it on the freeway/highway at 65 MPH trying to keep up with modern cars and you'll be 10 to 12 MPG.

[Flathead]

What should I expect for  gas mileage?? I'm getting 12.5 mpg.  It's a 51, 217 ci in flathead  with the usual 3 spd trans.  It is a recent rebuild with about 2000 miles on it.  It was from a reputable shop.  It was balance and runs good; plenty of power, no oil burning.  I use only non-ethanol Hi Test. ( I can't get  non -ethanol regular.  I have electronic ignition.  I was hoping for about 18mpg.  Am I dreaming or is something wrong?
What do you think?