Gas Mileage is poor

[data89]

As the originator of this post, I want to add that the next tank fill showed a 12.12 mpg. It would seem that is as good as it gets. I'm going to make a third check, next fill up and then quit. Thanks for all the input, I feel better now.

[hpcgmc]

I drove my 67 shortbed all through high school and college- between about 1977 and 1991 (took awhile to get out of college).

I put a 283 with a Qjet 4 barrel out of 66 Chevelle in it in about 1983. I had 31" tires on it for most of this time. Straight freeway at 60 mph (speedo read 50) I would get 16-18 mpg. I've got my old "logbook" somewhere, I'll double check when I find it. I remember calculating that every 5 mph faster I drove, it cost me 1 mpg.