1970 LT-1 mpg

Discussion in 'Camaro Questions' started by Mrnmrssmith, Apr 9, 2020.

  1. Mrnmrssmith

    Mrnmrssmith Member

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    Finally got my car out for a cruise, first for this year. Over the winter I tuned up the motor, re build the 780 Holley, got the timing dialled in. Curious what mpg this car gets,( not that it really matters) I filled up with 94 chevron until nozzle shut off, drove conservatively for 46km/29miles, cruising 50-60 mph with about 5 stop lights. Pulled back into the same chevron and filled up again same way could not put anymore fuel in..it took 3.6 litres/.92 us gallon, which is 31-32 mpg or 7.5l per 100km. I have a 700r4 with 4.10 gears. Anyone else achieve these numbers? I realize it’s high for a 50 yr old performance engine, I would not have believed it without seeing for myself.
     
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  2. COPO

    COPO Veteran Member Lifetime Gold Member

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    If your worried about gas mileage with these calculations in an old muscle car then it’s time you need to sell it.
     
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  3. Mrnmrssmith

    Mrnmrssmith Member

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    Not worried, as I stated. Just found it abnormal.
     
  4. wnmech

    wnmech Veteran Member

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    That’s awesome gas mileage my pure stock 71Z28 RS with the Holly 780 carburetor and a turbo 400 with the 373 gears only gets 10-11 MPG. But like COPO said I’m not worried about gas mileage but was also just curious.
     
  5. twestrup

    twestrup Veteran Member Lifetime Gold Member

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    When mine needs gas, I fill it up. Could care less about MPG, just saying. That me.
     
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  6. Mrnmrssmith

    Mrnmrssmith Member

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    I hear ya, I’ve never figured out my mileage before. But doing so, does tell a tale of how your motor is running. Looking forward to more cruising this summer, as I haven’t had this car on the highway much.
     
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  7. tom3

    tom3 Veteran Member

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    Best I ever did with my 70 was 25mpg in back to back fillups. That was built for mid range power and fuel economy. Premium fuel only. More of an experiment than anything else but it actually ran pretty darn good too.
     
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  8. McCune

    McCune Veteran Member

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    In 1985 my 73 Z28 4 speed wit 4:10 gears got 18 MPH on 300 mile hwy drive. Speed limit was 55 and i would push it to 60.
     
  9. badazz81z28

    badazz81z28 Veteran Member

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    MPG is such a dynamic thing...I get way better gas mileage in the Dodge Ram than the wife does...A lot of it is how you drive....

    For starters you have a overdrive transmission. If your light on the pedal and mostly cruising, mileage will be better than stop and go and hammering the gas. You could also question with non stock gears and transmission, the Speedo and such is accurate...that could throw your numbers off.

    I agree with the others, on my Camaro I only pay attention to needle when it’s close to empty.
     
  10. Mrnmrssmith

    Mrnmrssmith Member

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    Absolutely, a lot of factors come into play. I went for this drive with that in mind, which I used gps to track miles...again just curiosity. I also made a few minor changes, tuning, speedometer calibrated and added a vacuum gauge inside. The overdrive definitely makes a big difference, along with the vacuum gauge you can monitor what rpm the motor likes, in turn helps with fine tuning=morepower.
    One time deal...I like my highway speeds to be around 75mph so overall mpg not much of a concern
     

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