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Cannot solve problem with '39

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  • Cannot solve problem with '39

    1939 Ford Deluxe Coupe, 85 hp. V8. Holley 94 rebuilt carburetor, 59000 miles showing, but odometer is not working. Non ethanol gas is used.

    Heads were removed for inspection. Engine appears to have never been overhauled based on inspection of pistons and valves. Pistons and valves heavy with dry carbon. Nothing wet around piston/valves. All pistons stamped STD and do not wiggle, do not appear to be loose. No wear sign around cylinder walls, no ridge at top of cylinder. There is evidence the intake manifold has been removed at one time. ??? Compression test run from 77 to 89. Engine does not knock, sounds like a Singer at idle.

    Car starts and idles well enough but does not run well particularly under load. As I shift through the gears it runs progressively worse as speed/rpm’s increase. When I accelerate in first gear about the time to shift to 2nd it’s rough, shift into second and it runs pretty good until it’s time to shift to third when its rough again. At steady speed is porpoises badly. With footfeed on floorboard it begins to stall and gets progressively worse until it would stall out. It does not backfire. Carburetor leaks a little. Not sure where the body is leaking.

    The electrical system has been overhauled: new plugs (two sets of H12) gapped at .025, new plug wires, rebuilt coil from Skip, new condenser, new points, new rotor (Ford Script) new distributor caps, gaskets, new ignition switch, etc. Plugs torqued to 25 lbs. Head nuts torqued to 50lbs.

    The carburetor has been taken down twice in an effort to solve the problem. New kits were used both times and great diligence was used to clean and properly adjust the carb based on sound and experience. Vacuum line is clear. Fuel line is clear from tank to carb and properly filtered.

    I am receiving conflicting information from people I respect who have a good degree of mechanical knowledge about old cars. Their experiences range from Porsches to Packards, and one has lifetime experience with Early Ford V8’s. We all are nearly as old as the car for what that’s worth!

    One suggest “the engine should be overhauled. It’s old, its background is unknown. Most cars from this era are due for overhaul at 60 to 70,000 miles. There probably is a ring problem and/or bad valves. Everything else has been tried and not solved the problem. It’s time for overhaul.”

    Others suggest “it is a lack of air. There is not enough air to properly burn the fuel being delivered. Most likely is the carburetor, more specifically the Venturi. Could even be a rag left in the intake, but there is an air restriction. The marginal compression readings are not bad enough to cause the degree to which the car runs so poorly.”

    What is your take on the situation? Thanks for your response.

  • #2
    My take is you need to do some real diagnosing. If the engine runs good at idle with no missing, smoking or blowby, i am thinking its ignition or fuel. Why you were told the motor needs an overhaul is beyond me with what your describing. Adding your general location to your profile may assist you in getting someone close by to help. It seems some are offering the shot gun approach, which never really works.

    Have you checked fuel pressure and spark when the problem is occurring??

    Oh and welcome to the forum!!
    3~ Tudor's & 1~ Coupe
    Henry Ford said,
    "It's all nuts and bolts"
    "Start by doing what's necessary; then do what's possible; and suddenly you are doing the impossible."

    Mitch's Auto Service ctr


    • #3
      First, WELCOME to VFF W1964

      In your description you make no mention of fuel pump. Is it stock on the rear of the intake manifold, or has it been changed to electric?

      You do not need an overhaul with the compression reading you have, but I do believe your head torque is a bit light, and since you did have the heads off, who/which gaskets did you use, and have did you check the compression before or after changing the head gaskets?

      Also something that could be a cause, what/which intake manifold do you have? And did you check it for surface flatness, both top and bottom, and what did you torque that down to and which gasket did you use?

      Without listening to the car driving there are several possibilities of what could be wrong. As I have asked, if you can answer, that might help narrow it down a bit more.

      And as Mitch said, help us help you with some type of location. We surely don't need an address, but at least a town and state please. If I am close, I am retired and available for help. I love those V8 85s.

      Do you know what jets are in the 94?
      You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!


      • #4
        This could be a symptom of a plugged exhaust-muffler. Mice love em.



        • Mitch
          Mitch commented
          Editing a comment
          Welcome John

        • DaWizard
          DaWizard commented
          Editing a comment
          Hey John, WELCOME to the VFF !!

          Excellent observation John. It is true that a plugged exhaust will cause high speed troubles.

      • #5
        Use your vacuum gauge to determine if the exhaust is plugged.


        • #6
          Looks like the original poster may have flown the coupe!
          The plugged exhaust is a real possibility.
          A couple others would be collapsing fuel line (hose) restricting flow or poor venting of the fuel tank.
          With the takeover of unleaded fuels across our great nation, I've started to rely on just a little bit of technology for some of the tougher ones. An Innovative Motorsports Wideband O2 sensor ::

          will tell you if you're going lean or rich.
          We may never know what his problem is or was..
          Regards - Randy
          Randy's Rod Shop
          1933 Ford Tudor "Bugsy"


          • #7
            You know, I'm glad you brought this back up Randy. I was thinking, in my early days we used to have the spring loaded butterfly valves at the exhaust connections and the springs could be weak enough to restrict the flow, or if running stock exhaust, the crossover could be blocked as well.
            You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!


            • #8
              DA - Are you talking about a heat riser valve like the one pictured here?
              I can't tell you how many of those I have to replace or try and break loose over the years when they rusted themselves tight.. When they rusted up, it was only a matter of time before the exhaust crossover port in the intakes would plug up...
              You do not have permission to view this gallery.
              This gallery has 1 photos.
              Regards - Randy
              Randy's Rod Shop
              1933 Ford Tudor "Bugsy"


              • #9
                Randy, THAT is exactly what I was referring to! I too have removed a few of those in my days.
                You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!


                • Mitch
                  Mitch commented
                  Editing a comment
                  they were used up through the 70's

              • #10
                I read your description of work done on ignition system. All good but didn’t see “new coil” Skip probably did but might want to check. Not sure if Skip uses new or rebuilds. No reflection on Skip as from reading threads know he’s good. Just sounds to me like you might have a bad coil or condenser. I’ve had a couple go bad on me & when they start to fail sounds a lot like your description then progressively with less & less rpm under load they cause the engine to run rough & stall. Just a thought


                • #11
                  condenser or advance. Send the dist to Bubba.
                  Paul in CT


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