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  • #16
    Not a coincidence?

    Eric,

    I thought it was not a factor but, given your proposed solution to the problem, maybe it was: Both stalling events occurred immediately after I had stopped to put gas in the tank.

    Cheers,
    Richard, '66 Thunderbird Hardtop, 390FE, Edelbrock Al heads, Comp cam, Street Demon 650 carb. Visit my restoration blog at hwythunder.com.

    Comment


    • #17
      Originally posted by HighwayThunder View Post
      Eric,

      I thought it was not a factor but, given your proposed solution to the problem, maybe it was: Both stalling events occurred immediately after I had stopped to put gas in the tank.

      Cheers,
      Do you have a vented gas cap?

      John
      John Pizzi - Squarebirds Administrator

      Thunderbird Registry #36223
      jopizz@verizon.net 856-779-9695

      http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

      Comment


      • #18
        No, gas cap's not vented. Should I just drill the hole in the cap?

        It's dawning on me that vapor lock may have been the problem the whole time. I'm also planning to re-route the gas line, not so close to the engine heat, and insulate it.
        Richard, '66 Thunderbird Hardtop, 390FE, Edelbrock Al heads, Comp cam, Street Demon 650 carb. Visit my restoration blog at hwythunder.com.

        Comment


        • #19
          Originally posted by HighwayThunder View Post
          No, gas cap's not vented. Should I just drill the hole in the cap?..
          NO! Your original cap was vented and your present cap should be, too.

          You get two choices:
          Vent the tank with a pipe that runs through your trunk and out the filler housing (outside) OR
          Use a vented gas cap.

          A small hole in your filler tube is NOT an option and is dangerous. These cars left the factory with no fuel issues. Get back to 'stock' and you will be good, so buy a vented gas cap. They don't cost much. - Dave
          My latest project:
          CLICK HERE to see my custom hydraulic roller 390 FE build.

          "We've got to pause and ask ourselves: How much clean air do we need?"
          --Lee Iacocca

          Comment


          • #20
            Oh - yea - forgot to mention. Didn't want to drill a hole in my cap because it was the original one.



            Don't believe the OEM cap was vented (at least on the '60)

            When I tried a vented cap I used one similar to this although the tabs hit the license plate flap on the '60 (so I had to bend them down) plus it was a PITA to remove because the side tabs were not very big and that made it hard to twist.




            That filler neck hole - dangerous - probably....but think about this.....

            The OEM 4100 carb has a vent hole on top directly above the front fuel chamber. If either of the floats in the carb stick open - the carb dumps the excess fuel on top of the engine right behind the distributor.

            Fuel + heat + spark = Fire.

            Yep - been there - done that




            So I didn't think the small hole in the filler neck would be any more dangerous than the vent hole on the carb.

            Figure if I see fire back there I'll just put the pedal to the medal and out run it.



            Eric

            (definitely use the hole in the filler tube as a last resort though - hard to fix except maybe with JB Weld)
            Last edited by DKheld; March 13th, 2017, 03:14 PM.

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            • #21
              My post assumed you have a Squarebird but the information I gave about venting still stands. You don't want a pressurized gas tank, ever.

              New cars draw a vacuum on the fuel tank to make sure there is no pressure. They capture and burn those fumes, not because the smell of raw gas is nasty but because it is explosive.

              Your fuel tank should never produce so much pressure that it blows gasoline past your carb's needle valves. Remember, the fuel line delivers liquid gasoline, not fumes. Those little floats cannot stop more than six pounds of pressure, otherwise they spew into the bowls, out the vents, and onto your hot engine.

              If your tank is not vented, to prevent pressure buildup use a vented gas cap. - Dave
              My latest project:
              CLICK HERE to see my custom hydraulic roller 390 FE build.

              "We've got to pause and ask ourselves: How much clean air do we need?"
              --Lee Iacocca

              Comment


              • #22
                Moved Fuel Line, but still get stalls

                Here's a pic of the new fuel line. It's up off the engine and insulated from the heat. Nonetheless after warmed-up and then turned off, the car will stall after restart.

                What I've noticed is that when that happens, the fuel filter will not fill, even with just the fuel pump on (refer to 2nd pic). My theory is that the unfilled part of the filter is a pressurized vapor keeping the filter from filling with liquid.

                What about the carburetor? Could it be I need to put a thermal block between the carb and the aluminum intake manifold?
                Attached Files
                Richard, '66 Thunderbird Hardtop, 390FE, Edelbrock Al heads, Comp cam, Street Demon 650 carb. Visit my restoration blog at hwythunder.com.

                Comment


                • #23
                  Did you ever get a vented gas cap. Remove the cap to relieve the pressure and then see if it will pump.

                  John
                  John Pizzi - Squarebirds Administrator

                  Thunderbird Registry #36223
                  jopizz@verizon.net 856-779-9695

                  http://www.squarebirds.org/picture_gallery/TechnicalResourceLibrary/trl.htm

                  Comment


                  • #24
                    Originally posted by HighwayThunder View Post
                    Here's a pic of the new fuel line. It's up off the engine and insulated from the heat. Nonetheless after warmed-up and then turned off, the car will stall after restart.

                    What I've noticed is that when that happens, the fuel filter will not fill, even with just the fuel pump on (refer to 2nd pic). My theory is that the unfilled part of the filter is a pressurized vapor keeping the filter from filling with liquid.

                    What about the carburetor? Could it be I need to put a thermal block between the carb and the aluminum intake manifold?
                    I doubt your theory re the 'pressurised vapour' however in any event I would have put the filter on that vertical section of fuel line above the fuel pump.
                    If it WAS vapour under pressure in the filter it would vent itself through the carb as soon as the fuel in the fuel bowl dropped its level.

                    I also doubt the necessity to put in a thermal block.

                    My 2 cents worth.
                    A Thunderbirder from the Land of the Long White Cloud.

                    Comment


                    • #25
                      I see Street Demon carbs need a bigger accelerator squirt nozzle when using larger cams and more cubic inches. The standard nozzle is .031 in size. Some of the symptoms you describe are caused by the above nozzle or bad vacuum.

                      Comment


                      • #26
                        Cavitation

                        I noticed that my feed tube to the fuel pump is 5/16". The main tube running under the car is 3/8", and the new tube I installed over the engine is 5/16". I mentioned this to an ME as a possible cause of the problem. He immediately suggested it could be a cavitation problem.

                        "The cavitation phenomena occur in regions where large pressure drops results in the local pressure falling below the vapor pressure, resulting in formation of vapor bubbles. Typically for pumps, cavitation occurs in the suction side of the pump blades, which in turn results in a reduction of effective area of the blade, thereby diminishing the efficiency of the pumps."
                        (SAE, Predicting cavitation in fuel pumps, 03-Jan-2014, http://articles.sae.org/12709/)
                        Causes of Cavitation:
                        "Having the pump at too high of a distance above the fluid source
                        Having too small of a diameter of suction pipe
                        Having too long of a distance of suction pipe
                        Having too many fittings on the suction pipe
                        Handling a liquid with a low vapor pressure
                        Running the pump too fast"

                        (Dale Conway, Pump cavitation diagnosis and control, 2/18/2010, http://www.flowcontrolnetwork.com/qa...nosis-control/)

                        I'm going to replace the 5/16" tubing with 3/8" and re-test.

                        Cheers,
                        Richard, '66 Thunderbird Hardtop, 390FE, Edelbrock Al heads, Comp cam, Street Demon 650 carb. Visit my restoration blog at hwythunder.com.

                        Comment


                        • #27
                          You don't have cavitation, or vapor lock. OEM fuel pumps are diaphragm-type so there is no high speed vanes or blades. We never heard a word about taking John's suggestion in regards to the tank cap. Aside from all that, your car and millions of others worked perfectly fine from the factory and for many years.

                          You MAY have:
                          A restricted pickup screen,
                          A collapsed fuel line,
                          A pinched fuel line,
                          Carb issues.

                          Your engine will run around town nicely with a 1/4" fuel line. - Dave
                          My latest project:
                          CLICK HERE to see my custom hydraulic roller 390 FE build.

                          "We've got to pause and ask ourselves: How much clean air do we need?"
                          --Lee Iacocca

                          Comment


                          • #28
                            Originally posted by HighwayThunder View Post
                            What about the carburetor? Could it be I need to put a thermal block between the carb and the aluminum intake manifold?
                            No it does not. I've run these exact carbs on large mud trucks
                            that the radiator is clogged with mud, truck was pushing 230 and
                            have had zero problems with heat from the carb.

                            Get a cheap electric fuel pump and mount it right in front
                            of fuel tank. I did this due to the "pushrod" that is required
                            for the funky 430 fuel pump actuation.

                            If you want fuel lines to look authentic (on the 430, the
                            upside down fuel pump on top front of engine is a nice
                            conversation piece), you can run fake lines (I did) in
                            and out of pump and "hide" real fuel line coming up back of engine.
                            59-430-HT

                            Comment


                            • #29
                              Stock Ignition?

                              HIGHWAY Thunder,, still stock ignition?? sounds like condenser prob or if electonic , bad ignition module..if you still suspect fuel related,,,you MUST put guages on and t/shoot that system completely. This type of prob can drive you to selling car and the growin Roses for a hobby CHEERS TERRY

                              Comment


                              • #30
                                Originally posted by HighwayThunder View Post
                                ...What I've noticed is that when that happens, the fuel filter will not fill, even with just the fuel pump on (refer to 2nd pic). My theory is that the unfilled part of the filter is a pressurized vapor keeping the filter from filling with liquid...


                                Your float bowls are vented to the carb throat. The floats only close-off supply when enough LIQUID gasoline lifts the floats. A constant flow of gasses will simply vent out past the needle valve as it remains open until the float closes it. - Dave
                                My latest project:
                                CLICK HERE to see my custom hydraulic roller 390 FE build.

                                "We've got to pause and ask ourselves: How much clean air do we need?"
                                --Lee Iacocca

                                Comment

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