Choke Geometry Help

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  • joe_db
    Afourian MVP
    • May 2009
    • 4544

    Choke Geometry Help

    My engine has always been a little slow to start for the first start of the day. After that, it starts right up. I always attributed that to me running the gas out at shutdown.
    Lately it had gotten much worse, with the December weather the engine could be chilly in the morning. Also the choke cable was getting very hard to pull. I decided some investigation was in order and discovered the choke cable had broken internally and I had no choke at all. I guess it is a miracle the engine could start even with difficulty on a cold morning. Choking the engine by hand it starts more or less instantly now, cold or hot, fuel run out or not run out
    I ordered a new Moyer cable and installed it. It turns out I have a geometry issue. The choke cable feeds through a clamp and then it goes through the little arm at activates the choke. The illustration shows the angle of the cable, the red line is choke OFF and the purple line is choke ON. The choke cannot make it all the way to full on, it tries to make the cable take a sudden bend it just won't do. I get a range of motion from off to maybe 2/3s choke. For an updraft carb in winter, it needs to be 100% choke.
    So before make some big mess, is there an easy way to change this geometry? What I am looking for is making the full on lever position farther forward, giving more distance from the cable clamp.
    Attached Files
    Last edited by W2ET; 01-01-2022, 12:57 PM.
    Joe Della Barba
    Coquina
    C&C 35 MK I
    Maryland USA
  • JOHN COOKSON
    Afourian MVP, Professor Emeritus
    • Nov 2008
    • 3501

    #2
    You need adjust the fixed arm. There is a screw that holds a sort of circular plate in place - that is where the adjustment is.
    I scribed a line on the plate and carb body with diamond tip pencil before disassembly so I could line up the fixed arm correctly after doing a carb overhaul so I didn't have to guess the correct position when I reassembled the carb.

    ex TRUE GRIT

    Comment

    • joe_db
      Afourian MVP
      • May 2009
      • 4544

      #3
      This one?
      That seems easy enough.
      Attached Files
      Last edited by joe_db; 12-18-2021, 12:19 PM.
      Joe Della Barba
      Coquina
      C&C 35 MK I
      Maryland USA

      Comment

      • JOHN COOKSON
        Afourian MVP, Professor Emeritus
        • Nov 2008
        • 3501

        #4
        I think it's the or these. It's been a few years since I've done this. The little circular plate that has the fixed arm attached needs to be rotated.
        If necessary the angle that the choke cable approaches the carb will need to be adjusted so there are no tight bends in it.
        Also the movable arm should not touch the fixed arm when the choke is fully closed.

        ex TRUE GRIT

        PS: A crumpled rag under the work area will catch the small parts you are going to drop.
        Last edited by JOHN COOKSON; 12-18-2021, 12:32 PM.

        Comment

        • joe_db
          Afourian MVP
          • May 2009
          • 4544

          #5
          Thanks!
          And thanks to Moyer for getting me the cable fast! Do NOT cheap out on these, pretty much every single other kind of cable will corrode and die on you.

          A general note - this was a frog boiling issue. Between the cable getting worse and the temperatures dropping, the first start of the day just kept getting a little worse. The A4 is NOT a hard to start engine, so if it is something is wrong somewhere.
          Joe Della Barba
          Coquina
          C&C 35 MK I
          Maryland USA

          Comment

          • JOHN COOKSON
            Afourian MVP, Professor Emeritus
            • Nov 2008
            • 3501

            #6
            If you need choke adjusting instructions let me know.

            ex TRUE GRIT

            Comment

            • Dave Neptune
              Afourian MVP, Professor Emeritus
              • Jan 2007
              • 5115

              #7
              The "pivot" on the end of the choke arm should minimize the wire cable flexing. And what John said for adjustments.

              Dave Neptune

              Comment

              • joe_db
                Afourian MVP
                • May 2009
                • 4544

                #8
                I sort of got it. The nut that holds the lever arm (purple) can be loosened to make the adjustment I wanted. It is farther out now so the choke can be pulled all the way on.
                The problem is the "pivot" does NOT pivot (see black arrow). That causes bad geometry, but now I have it at the full-open setting, not the full-closed. I actually did not realize that thing could pivot! Once I get that pivoting my troubles should be over.
                Attached Files
                Joe Della Barba
                Coquina
                C&C 35 MK I
                Maryland USA

                Comment

                • Dave Neptune
                  Afourian MVP, Professor Emeritus
                  • Jan 2007
                  • 5115

                  #9
                  The end of the choke arm should have a pivoting pin with a set screw to hold the choke cable in place. That piece may not be what you have from the looks.

                  How does the cable attach?

                  Dave Neptune

                  Comment

                  • Marian Claire
                    Afourian MVP
                    • Aug 2007
                    • 1769

                    #10
                    Not sure about late model carbs but I know that on the early carb you can adjust the choke attachment to work with the cable coming from any direction. Looks to me like rotating the fixed arm counterclockwise a bit along with the adjustment you made would give you a straighter approach and a little more travel distance. My fixed arm and the moveable arm are almost in a straight line on the MC.

                    Dan S/V Marian Claire
                    Last edited by Marian Claire; 12-19-2021, 09:58 AM.

                    Comment

                    • JOHN COOKSON
                      Afourian MVP, Professor Emeritus
                      • Nov 2008
                      • 3501

                      #11
                      Originally posted by Marian Claire View Post
                      . Looks to me like rotating the fixed arm counterclockwise a bit along with the adjustment you made would give you a straighter approach and a little more travel distance. My fixed arm and the moveable arm are almost in a straight line on the MC.
                      Dan S/V Marian Claire
                      This is the ideal set up. On some boats (such as my ex Cat 27) it was necessary to modify to achieve this. The cable was suspended in space between the cockpit and carb until I fixed it. In any case the swivel on the movable arm on a late model carb will compensate for any angle that the cable approaches the carb and allow for full movement of the movable arm.

                      ex TRUE GRIT
                      Last edited by JOHN COOKSON; 12-19-2021, 01:31 PM.

                      Comment

                      • joe_db
                        Afourian MVP
                        • May 2009
                        • 4544

                        #12
                        I found an old carb in my shed and the choke cable attachment DOES swivel on that one. I think I am going to swap the choke arms or at least break the new one free so it can swivel too.

                        FYI - the difference between full choke and almost full choke is huge on a cold winter morning, the engine loves that full choke.
                        Joe Della Barba
                        Coquina
                        C&C 35 MK I
                        Maryland USA

                        Comment

                        • edwardc
                          Afourian MVP
                          • Aug 2009
                          • 2513

                          #13
                          Years ago, I had this exact same "geometry" issue with my choke. The pin didn't pivot, and I could either adjust to get full open or full close, but not both.

                          I came up with a "bush fix" that has actually worked quite well over the years.

                          First, I unclamped the choke cable body, removed the core wire from the pin, and locked the set screw all the way down. This still left some "shoulder" exposed under the setscrew head.

                          Next, I took a needlenose pliers and bent a 180 degree hook in the tip of the cable wire.

                          Lastly, I placed the hook over the shoulder of the setscrew, and clamped the cable body in place at proper location.

                          Now when I pull the choke on, the hook freely pivots on the setscrew as it pulls, allowing full travel. And, since the choke assembly is spring-loaded, as I release the choke the spring returns it, keeping the hook fully engaged at all times.

                          And this "fix" has had an added benefit. On my boat, with it's v-drive installation, reinstalling the carb is done largely by touch. And inserting that core wire in the pin and adjusting and tightening it was always the hardest part! Now it's easy. I just place the hook on the screw and clamp the body in place.
                          @(^.^)@ Ed
                          1977 Pearson P-323 "Dolce Vita"
                          with rebuilt Atomic-4

                          sigpic

                          Comment

                          • joe_db
                            Afourian MVP
                            • May 2009
                            • 4544

                            #14
                            Swapping the choke arm out for one where the cable fitting rotates did the trick!
                            Christmas a day early
                            I had never realized that fitting was supposed to be loose all this time
                            Joe Della Barba
                            Coquina
                            C&C 35 MK I
                            Maryland USA

                            Comment

                            • sastanley
                              Afourian MVP
                              • Sep 2008
                              • 7040

                              #15
                              The weather was so nice yesterday (actually better today), but yesterday I thought about this thread, and went to the boat and did some fiddling with my choke to make sure it closes all the way. It is still hard to start when it's been sitting for several weeks like yesterday, but my lighted mirror shows me the choke is closed. When we use the boat regularly, she normally starts up in seconds. Good exercise anyway.
                              Last edited by sastanley; 12-25-2021, 11:04 PM.
                              -Shawn
                              "Holiday" - '89 Alura 35 #109
                              "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
                              sigpic

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