Hey Leonard;
I gotta think your truck should do better than that.
To get the best mileage advance your timing as far as it will go before pinging. Turn your dizzy about 1/16 of a turn CCW and drive it down the road a little with your foot in the throttle. If you don't hear any pinging repeat the 1/16 turn and do it agan. Eventually you'll begin to hear a little pinging sound (pre-ignition, or what we used to call "spark knock"). At that point turn the dizzy back (CW) 1/16 and lock it down.
Make sure your tires are all inflated properly.
How "mild" is that cam?
Are you running the stock rear gear? A 4:11 will really pull your mileage down on the highway.
Good luck and keep us posted.
