[Ed Snyder]

Originally Posted by jagarra

I have been tracking the MPG on my truck since i have had it, it has finally settled on about 6.2 MPG, OUCH!!!!

I have a 500 CFM Holley on it, recent tune, valve adjustment, runs like a top just horrid mileage. I have the stock 3.54 gearing and a 420 tranny. The entire fuel system was replaced after I bought it

I did try jetting it smaller than what came with carb, mileage went down to 6.1, so I put the stock jets back in, went up to 6.27. I can go smaller as I bought 2 sets, each going down one notch from stock. I do have a big air cleaner with a paper filter so it is getting a lot of air.

the elevation here is 4450

Lots of things can affect mileage. Some things to check are ignition timing, tire pressure, brakes dragging, and front end alignment. I'm sure others here can suggest more to check. Are you 100% sure the rear end is a 3.54? You should be getting closer to 10 MPG if not better. If it sits for a long time, you could be losing some fuel to evaporation. Lots of hilly driving obviously affects mileage too.