Gas mileage on a 1977 Newport with a 400

Later Model C Bodies - "The Formal Years"

  1. Pclancy

    Pclancy Member FCBO Gold Member

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    Gentlemen:

    I checked for threads on improving gas mileage. Didn't see much. Did I miss them?

    Anyway, I'm not foolish enough to expect good/great mileage from my baby. But she only gets about 10 MPG in mixed city/road driving. Maybe 12 or so on the road.

    Is this to be expected? I see posts where c-body owners talk about numbers much higher, yet with the same engine. I wonder how they do that.

    I recently disconnected my lean burn, moving to an orange box system and keeping the TQ carb. The engine seems to be in good tune. Besides the obvious stuff, like keeping the tires inflated correctly, is there anything I'm missing?

    I'm happy with my baby as she is, but like anyone, if I could get better mileage w/o spending a ton of money, I would do it.

    Ideas?

    Thanks
     
  2. detmatt

    detmatt Old Man with a Hat FCBO Gold Member

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    Loose the spare tire, back seat, all the hardware for your ac, keep no more than a quarter tank in it and ditch the skirts.
     
  3. live4theking

    live4theking Old Man with a Hat

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    Matt,
    That sounds like a pretty hard diet.
     
  4. Ripinator

    Ripinator Senior Member

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    What is your rear-end ratio? If its a 3.23, I think your mileage is pretty typical.

    One thing you could do to improve your mileage slightly is to add one ounce of marine 2-cycle oil - with TC-W3 - to each five gallons of gas. This has the beneficial effect of providing lubrication to the various parts of the fuel system (fuel gauge sender, carb, intake valve seats, etc.). It also provides some lube to the piston ring packs, which results in better compression, thereby increasing your mileage and providing a smoother running engine. I run this stuff in all my cars - even my old Harley - and it works. You can read all about it here:

    Been testing Oil
     
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  5. detmatt

    detmatt Old Man with a Hat FCBO Gold Member

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    What?, it's not like I told him to drill a bunch of holes in his core support.
     
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  6. commando1

    commando1 Mr. Normal FCBO Gold Member

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    Better than I get. Waaaaay better.

    People just refuse to believe there was an era when 10 mpg was the norm.
     
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  7. Mr C

    Mr C Senior Member

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    Yes, C bodies and city driving= poor mileage. I get @ 10 mpg city...sustained Hwy mileage (road trips) up to 18 mpg with my wagon (I don't know why)...only ever managed a best of 16 mpg with C body cars.
    As mentioned rear end ratio will be a big factor.
     
  8. Carmine

    Carmine Old Man with a Hat

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    Keep skirts. Lightweight and improves aerodynamics.

    What is your idea of "road"? 45 mph top streets with occasional stoplights or 75 mph cruise for miles? If it's just a bunch of city traffic, most of your improvement need to come from driving habits.
     
  9. Pclancy

    Pclancy Member FCBO Gold Member

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    What's the best way to see what your rear end ratio is? My vehicle is canadian, and I'm not sure you can use the VIN?
     
  10. Pclancy

    Pclancy Member FCBO Gold Member

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    By road, I meant interstate. Non stop (except for normal breaks) driving at between 60-70. From memory, about 12-13 MPG?

    In the city, 9-10 is what I get. Note, I drive her really easy, rarely if ever allowing the "fuel pacer" to light up.

    I knew mileage would be lousy when I bought the car. So I'm not disappointed. It's just that you read folks (sometimes) claiming much more with the same car/engine, and it make you wonder.
     
  11. detmatt

    detmatt Old Man with a Hat FCBO Gold Member

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    There might be a tag on one of the studs that hold the center section to the housing with the ratio stamped on it. If not the build sheet or fender tag will hold the details depending on what year the car is. You can also get the rear tires off the ground and count how many rotations the drive shaft turns in one full rotation of the tire.
     
  12. Dobalovr

    Dobalovr Well, that was not what I thought it was FCBO Gold Member

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    It's a Canadian car convert it to Imperial Gallons ....you will feel better about it :poke:

    :rofl:

    Better yet Litres/100kms
     
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  13. 67Monaco

    67Monaco Old Man with a Hat

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    How many gallons per mile is more like it....
     
  14. Snotty

    Snotty Senior Member FCBO Gold Member

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    Dump that TQ and get an Edelbrock - you'll see 1-2 MPG better.

    On my 440 I get 8-12. Best I have ever seen was 15.
     
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  15. 1978 NYB

    1978 NYB Warfighter FCBO Gold Member

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    I can get 14-15 mpg on the highway. Day to day around 10-12 mpg.

    Edelbrock 1406 on both of mine.
     
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  16. polara71

    polara71 Old Man with a Hat FCBO Gold Member

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    I always am skeptical of much higher claims than where youre at
     
  17. mr. fix it

    mr. fix it Old Man with a Hat

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    This is where the poly shines boys! 20.5imp mpg on the last rip but you all know that.:thumbsup:
     
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  18. Knebel

    Knebel Senior Member

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    Know what, the mileage pisses me off too. I originally looked for a car with a 318 and found my fury where everything was perfect, except, after only getting 9mpg or so, i cleaned all the crud off the engine and discovered it was a 360, and not a 318 as advertised. Im pissed about it but live with it. Look on amazon for engine oil called Liqui or Lubro Moly MoS2. That makes the engine way smooth and gains a little bit after somewhat 100miles of driving. I have put a 1500$ EFI on my car which also improved mpg close to nothing.
     
  19. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    Sigh.... These cars just don't get good gas mileage. You might be able to bring it up a MPG or two with some tuning and keeping your foot out of the carburetor.

    Anything that you do that involves throwing money at the car will probably never pay for itself. Just do the math sometime and remember that it's a limited use car that you aren't putting enough miles on to justify anything.

    The best thing to do is just not pay attention at the gas pump. Just think about it as money spent on having fun.
     
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  20. jct

    jct Senior Member FCBO Gold Member

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    i love the power on demand feeling from the 383 compared to my lil 1.5L engine D.D.