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57 Commander Black sooty tailpipes

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  • Fuel System: 57 Commander Black sooty tailpipes

    Car starts and idles, runs well. No smoke while driving but tailpipes very black and sooty. I believe I have the carb as lean as possible. 259 2bbl, 3sp with overdrive. What correction can I make?

  • #2
    Take a drive on the highway for an hour or so and then see what color the tailpipes are.
    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


    • #3
      Drove and hour and a half to a car show this morning, black.


      • #4
        FWIW, now that wideband O2 sensors and digital readouts are affordable, I no longer try to guesstimate WIGO with carbs. Fifty years of reading plugs and tailpipes are no longer accurate, as today's pump gas doesn't correlate. The O2 sensor will show one just how much he doesn't know about how the carb is really delivering air and fuel.

        The other problem is Studes with miles and age are prone to feed the engine oil on one end and unmetered air on the other. No point in chasing the carb until it's verified the valve stem seals are new, the intake gaskets, distributor vacuum advance, power brake booster, carb gaskets, PCV valve, aren't leaking and the throttle shafts aren't loose in the bores.

        Once those issues are addressed, then perform a cold cranking compression test. Again, if there's blowby, the carb can't really keep the tailpipes clean.

        Most likely, you'll find it's a bit of all of the above.

        jack vines


        • #5
          Sounds right Jack. Carb’s been rebuilt but valve seals original to 51,000 mile car.


          • #6
            Plug reading still does correlate.
            BUT, the reading what the spark plug is telling you requires a different way of reading what it's telling you. Also, reading old (over about 5000 miles) plugs...well, it is sort of a crap-shoot, not overly accurate.
            You need to look for very different things on the plugs to get a reading (leaded gas vs oxygenated gas). More down deep between the plug body and the porcelain, vs the old days of right near the tip. Even the ground strap will show things more than the old days, but again, older (miles wise) spark plugs will not provide a good view of what's happening if the air fuel is more than a little off.

            And yes, what Jack says about the wide band air/fuel gauges is good. But it is another learning. You still need to understand what you are seeing and WHAT to adjust within the carburetor. There is more than JUST jets to deal with. You really need to understand the way they work, or you can get into trouble trying to understand what the A/F gauge is saying, then translating that into changes inside the carburetor(s)

            Tim -
            Do NOT pay any attention to the tail pipe. The spark plug will still tell you what it wants, but thinking the "OLD" (leaded gas) way of reading plugs will not get you anywhere. It's a whole new ball game with oxygenated fuel.
            Trying to read the tail pipe now days depends on the exhaust system itself, the amount of heat retained or cooled within the system. NOT accurate, any way you cut it.



            • #7
              Black sooty pipes could mean there is engine oil being burned. If the soot is black and slimy, then there is an oil consumption problem. If the soot is powdery, then it's gasoline. Have you run a fuel mileage test to see just how much fuel is being used? To me doing a consistent fuel mileage check goes a long way in showing how the engine is performing. Also keep in mind that ignition problems will also deposit soot in the pipes due to a weak spark. Bud


              • #8
                Click image for larger version

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ID:	1721574#4 cylinder example. Autolite 437 plug. Drove 109 miles today, mostly 45-55 mpg. Down about 2qts of oil since last full...145 miles. Previously added 1 1/2 qts after 501 miles of local short trip driving, 15-20 miles per no faster than 40-45.
                Last edited by tim333; 07-29-2018, 08:07 PM.