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  • M.p.g.

    Hi Guys, I just made a 320 mile round trip in the country. My T. Bird breezed all the way there & back. I travelled at 65-70 mph & my fuel consumption worked out to 17 mpg (Imperial), 14 mpg (U.S.) Any of you fellow T.Birders worked out your fuel consumption on a long trip? If so lets compare notes.

    Chris.....From OZ.

  • #2
    I can just get 14mpg at best on a long trip in my '66 T bird- and that's Imperial gallons!

    My F100 with warmed 429 gets 17mpg, maybe I need to get the carb on the T-bird rebuilt?
    A Thunderbirder from the Land of the Long White Cloud.


    • #3
      Chris on both my wife's 58 and my 60 I get 15 mpg ( converted as we are in km in Canada )
      Dano Calgary,Alberta Canada
      Thunderbird Registry
      58HT #33317
      60 HT (Sold )


      • #4
        I also get 15 MPG Imperial with my 1960 352.


        • #5
          Make no mistake, there are a LOT more ponies in your gas that you are not harnessing. Modern cars get at least ten mpg more. Why?

          Modern cars ATOMIZE the gas under 55 PSI (EFI) pressure for a much finer spray and better air mixture.
          Carburetors kinda dribble gas in under negative pressure because they suck gasoline through a verturi.

          Your engine was built to run on leaded gas with NO alcohol. Unleaded gasohol burns differently. Under optimum air:fuel ratio (14.7:1) your classic engine runs hot. To compensate for the heat problem you retard the timing which burns the fuel later and it actually discharges before the burn is complete. This cools the engine AND it loses HP.

          Now we come to a decision: Do we want economy and optimal HP or do we keep our classic engine stock and sacrifice economy?

          All the things a modern engine has can be done to an FE. "FAST" makes a wonderful Electronic Fuel Injection system that replaces your 4100 carb. It uses an oxygen sensor and a high pressure fuel pump to compensate for altitude, temp, etc. I will buy one either today or tomorrow from

          Your heads need hardened exhaust seats and stainless valves. Otherwise your valves will erode and recede. Eventually, you will run into this.

          OR, you can leave well enough alone and suffer terrible MPG and eventual receded valves. Yes, your car's economy is a lot worse than when it was new because the gas and oil back then were formulated differently. Back then, lead deposits used to form around your valves; something new mechanics have never seen. That's why a good long high speed trip made your engine run like a top but constant 'city driving' would load it up again.

          So, modern conditions are dramatically different for our classics. All classics. - Dave
          My latest project:
          CLICK HERE to see my custom hydraulic roller 390 FE build.

          "We've got to pause and ask ourselves: How much clean air do we need?"
          --Lee Iacocca

          From: Royal Oak, Michigan


          • #6
            I'm wondering if other countries have 10% ethanol in their gas, or is it just the U.S.?


            • #7
              I keep records of all my expenses in aCar on my phone. My best in the T'bird is 16.9 MPG, worst is 6.6 MPG. Average is 12 MPG. I don't drive it enough to worry about it.

              My Mazda3 DD has averaged 28.5 MPG over 9 years and my wife drives a Prius, averaging 40 MPG so I'm doing pretty well otherwise.
              DGS (aka salguod)
              1960 Convertible - Raven Black, Red leather


              • #8

                Yes Greg, we do have E10 here. Our Fuels at the regular pumps here in south Australia are 91 unleaded 95 unleaded & premium 98 unleaded octane. As well as the E10 that only the ignorant people use. I use the 98 premium with all my cars. It costs about 14 Cents extra per litre but I get a smoother ride & better Fuel economy. The extra that I pay per Litre makes up for the extra Miles & cleaner for the engine & other fuel related parts. Shortly after I purchased my T.BIRD almost 8 years ago I had my carby pulled apart 'cause it was running lean & I haven't touched it since. In the Suburbs I average around 12-13 MPG.

                Chris.....From OZ.