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  • Other: Studebaker V8 mileage

    What am I doing wrong? I have a 1960 champ. Short stepside bed, daily driver. It has the 3spd w/od R2 grind, Carter AFB maybe around 625 cfm (manual choke) I have changed rear end from a 4.09 to now a 3.92

    I am currently getting around 11 mpg

    I have a 1962 lark everything is the same except the rear end is a 3.73 and the lark engine has the WCFB. Last road trip I took was around 23 mpg

    Is the Carter too big? If that is the case is the air flowing through the carb too slow allowing the fuel to fall out of the air when airflow is forced to do that hard 90 at the base of the manifold? Or am I way off? Depending on travel speed I have observed way different vacuum readings at different RPMs. Does one get better economy with the engine spinning over quicker? Like around 2500-3000 RPMs (10-15” vacuum)? (seems like fuel would stay suspended in the air better) or is mileage better at lower RPMs with between 5-8” vacuum?

    I have been throwing around the idea of self learning fuel injection. Does anyone on the forum here run something like this on the daily? What would I expect in terms of a mileage increase? Gas prices are going up. I spend around $100 every week and a half right now. I’m optimistically thinking fuel injection would pay itself off real quick

    anything helps. Thanks in advance


  • #2
    The rear axle might be too tall. Mileage is not linear with RPM. There is a sweet spot.
    RadioRoy, specializing in AM/FM conversions with auxiliary inputs for iPod/satellite/CD player. In the old car radio business since 1985.

    17A-S2 - 50 Commander convertible
    10G-C1 - 51 Champion starlight coupe
    10G-Q4 - 51 Champion business coupe
    4H-K5 - 53 Commander starliner hardtop
    5H-D5 - 54 Commander Conestoga wagon
    56B-D4 - 56 Commander station wagon
    60V-L6 - 60 Lark convertible

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    • #3
      I agree Mr Radio Roy. The engine seems to be the happiest around 2500 RPMs

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      • #4
        If one wants maximum economy, the R1/R2 cam is not the way to go; but that bus has left. You're not likely to reinstall the stock cam.

        What you didn't mention is the compression ratio. Unless the compression is held to at least 9:1, the R cam just makes things worse

        The Carter 625 is really too large for a 289" and the properly tuned WCFB will always get better fuel mileage.

        Tuning for maximum fuel economy is a multi-variable regression analysis and the carburetor and distributor are crude instruments, but can be made less bad. In theory, current generation engines run lower RPM, a wider throttle opening and lower vacuum, which means less pumping loss, but they have direct injection and computer controlled spark. Our carburetor and distributor have to be tuned specifically for that condition. If the distributor vacuum advance falls away, then fuel economy goes down with less vacuum.

        jack vines
        PackardV8

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        • #5
          My 1962 Champ, 289, 4 speed, 4.09 rear end, Carter AFB , dual exhausts. Last time I checked got 8mpg. Sure sounds nice when I floor it and open the 4 barrel!

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          • #6
            Originally posted by rbisacca View Post
            My 1962 Champ, 289, 4 speed, 4.09 rear end, Carter AFB , dual exhausts. Last time I checked got 8mpg. Sure sounds nice when I floor it and open the 4 barrel!
            Exactly the Point, you don't put a 289 with a 625 c.f.m. AFB, R1 Cam V8 in a 3800 pound "Brick" like a Champ and then expect good Mileage.

            What about the Speedometer Gear, is it close enough to get the Odometer within 0.25 Miles of Correct with the Axle Ratio change and modern size Tires?
            StudeRich
            Second Generation Stude Driver,
            Proud '54 Starliner Owner

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            • #7
              What has been done to raise compression,which engine 259 or 289. might want to think about a head shave! Luck Doofus

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              • #8
                I'd expect something around the 12-15 mpg range with a V8 and 1:1 last ratio.......unloaded and driven like a friend

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                • #9
                  Originally posted by jackb View Post
                  I'd expect something around the 12-15 mpg range with a V8 and 1:1 last ratio.......unloaded and driven like a friend
                  For true. Over the 30-year span my C-cab E12 had the 224" V8, T98 4-speed and 4.10 gears, it averaged 12-14 MPG.

                  FWIW, how it was driven didn't make a great deal of difference. Heavy truck, small engine, small carburetor, it had to be run pretty hard just to keep up with traffic. On the highway, at 60-65 MPH, the engine was turning 2800 -3000 RPM and the fan noise was harder on the driver than was the RPM on the engine.

                  If a long highway trip was necessary, I'd remove the engine-driven cooling fan. Conventional wisdom says 60 MPH should generate enough air flow through the radiator that the fan wasn't necessary. On this particular C-cab, without the stock four-blade fan, the noise was way down to almost tolerable, but the coolant temperature ran 5 - 10 degrees higher.

                  jack vines
                  Last edited by PackardV8; 03-10-2021, 06:50 AM.
                  PackardV8

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                  • #10
                    392 is for drag racing or putting around the farm. The most cost effective way to change for improving mpg is often changing the diff. You'll need a 330 or so to do better.....or adding od.
                    Last edited by t walgamuth; 03-12-2021, 04:21 PM.
                    Diesel loving, autocrossing, Coupe express loving, Grandpa Architect.

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                    • #11
                      Originally posted by t walgamuth View Post
                      392 is for drag racing or putting around the farm. The most cost effective way to change for improving way is often changing the diff. You'll need a 330 or so to do better.....or adding od.
                      OP has a T86 with overdrive. The 3.92 becomes 2.74 and causes vacuum to drop to 5 - 8"; the reduction in distributor vacuum may part of his problem.

                      jack vines
                      PackardV8

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                      • #12
                        Static compression ratio is 8.5-1. It’s a 289 bored .030. Maybe 294 ci? The 11 mpg is truck only and empty and driven “friendly”. Tires are radials but not way big. Fronts are p215/75r15 and rears are p225/75r15. I am afraid to check mileage while loaded. I was worried about pinging when I rebuilt the motor since I use the cheapest fuel I can. I pull a tandem axle car hauler from time to time. I was worried about starting out with a load with anything less than that 4.09. That 1st is a little steep to take off with a load. I tried to tell myself I would make up for it in mileage. I also was not worried about fuel economy when I did the motor because gas was $1.60-ish a gallon back then.

                        Mr Jack Vines is right. I like the way the truck runs, I really don’t want to change cams. I would however be interested in learning about those offset keys to play with cam timing though. However I don’t think that will help mileage.

                        On the topic of vacuum. . . I assume that all I can do is play with centrifugal springs. Is there anything else I can do? I am running the windowless distributor (I tend to think that it has a better spark curve from the get-go). Are the electronic distributors any better? I might try different vacuum ports on the carb. I don’t remember which one was which between ported and non-ported but I know one of them will cause WAY too much advance at part throttle. I checked it once and it was like maybe 48 degrees btdc between cutting out

                        I just don’t understand how a V8 under 300 cubic inches can get such poor mileage. Feels like “ big block” mileage.

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                        • #13
                          With vacuum that low, the power valve pistons in the carb may not be getting sucked down enough to put the fat part of the metering rods in the jets. Maybe some softer springs?
                          Gord Richmond, within Weasel range of the Alberta Badlands

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                          • #14
                            You have a big thirsty carb, a tall rear-end, a performance cam, really crappy gas, and a pick-up truck. Mileage sounds about what you can expect. Whatever you do to improve mileage will not be cost effective, unless it is to install smaller jets in carb. Do you drive it enough for this to be a $ issue? Low vac is probably due to big carb.

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                            • #15
                              Mr Jeffry Cassel: It is getting quite expensive just to get around. I spend $100 every week to week and a half. I feel that whatever I do will pay for itself in time

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