noob needs help with mileage - only 10 MPG!

my 65 valiant average 17-18 with a burnt exhaust valve on cylinder 1 and points. Something to check there is a flapper valve on the exhaust manifold just below the intake. If it sticks shut you have a very large exhaust restriction which will severly hurt fuel economy. The board over at www.slantsix.org is less active than here, but there are a lot of people over there with slant specific experience.