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    Choke Question-gctid561064

    I apologize if this seems a little to simplistic of a question....but I can't seem to get this dialed in. When doing a cold start on the GM Marine 350 engine, do I want the choke totally closed, 3/4 closed or not at all. How many pumps of the throttle do you guys do as well.

    I have a Q-Jet that had a divorced choke on it, but with the new vortec intake I put a manual choke cable on it, as it's still works fine.

    All starts after the first are bump the key and off she goes....the first is usually hardest....because I'm sure I'm not doing something right. Your help would be appreciated.

    Thank You

    #2
    http://www.baylinerownersclub.org/in...g-issue#555161
    Joon, Kathy, Jaden & Tristan
    Uniflite 42 AC, DD 671N
    93 3058 sold
    92 2855 (day boat)
    91 Fourwinns 205 (lake boat)
    Longbranch WA
    Life is Good

    Comment


      #3
      Thank you for the link...I copy on the two pumps, and I've probably been giving it a tad to many...but what about the choke. I've made it manual, so should it be closed, cracked open ( the width of a nickel I've heard) or more?

      Thanks again.

      Comment


        #4
        You'll find the right spot for the choke with time. I'd say try 1/2 way choked would be a good place to start...... If it don't start or starts then quickly dies try 2 more pumps and 3/4 choke. Weather temp will have an affect also. The colder it is the more choke you may need.
        Dave
        Edmonds, WA
        "THE FIX"
        '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
        (.030 over-Vortec top end-part closed cooled)
        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
        Misc. projects thread
        https://www.baylinerownersclub.org/f...56-gctid789773

        Comment


          #5
          The choke adjustment is a little trial and error.

          There is a spec to start with but when it is stone cold over night It should be barley closed after a pump to set the choke and fast idle. The vaccum choke pull off linkage will be adjusted by bending so that when it fires up the linkage opens it enough to keep it from over choking (smoking and surging) As it heats up if the choke doesn't open the rest of the way soon enough (smoking and surging) then the coil needs to be moved a notch leaner (less tightly closed) . If the engine tries to starve out and die . move the coil a notch tighter closed. After one shot you won't get a accurate setting until the engine is stone cold again. If you are in very cold weather the setting will be different than summer in the desert.

          Even having adjusted them a few times there is still a little fooling around to get them just right.
          Carl
          2452

          Comment


            #6
            Sounds good...I'll try a little less choke and less pumps on the throttle and see what works best.

            Thank You all.

            Comment


              #7
              Many guys don't want to mess with it so they disconnect it or back off the adjustment. A friend has a oil squirt can with gas in it. A few squirts down the carb and it pops right off, It's usually good to restart until it sits overnight. It's not a bad Idea to have the cover open for start up inspection anyway.
              Carl
              2452

              Comment


                #8
                Duke, the Rochester Quadrajets are somewhat prone to early fuel evaporation. Sometimes as early as only several days.

                They are also known for having an epoxy closed-off manufactoring/machining ports that may leak fuel.

                With a mechanical fuel pump, our first few cranks may do nothing more than fill the fuel bowl.

                Until the bowl level is up, the accelerator pump may not fully function for good cold start enrichment.

                Also... until the bowl level is up... the choke plate restriction may not fully enrich the fuel mixture for a good cold start.

                This makes for difficult starts when the engine is cold......, even while we operate the choke plate, and work the accelerator pump.

                Point being...... it's easy to confuse not enough accelerator pump action, and/or not enough choke chimney enrichment with a less than full fuel bowl.

                If the epoxy is holding...... the "cure" can be as simple as an electric fuel pump with a momentary helm switch used in lieu of relying on the electric fuel pump start-by-pass circuit....., of which stil requires cranking.

                We hit the momentary switch.... and the pump fills the fuel bowl without cranking.

                An easy method to check this, will be to prime the fuel bowl via the fuel bowl vent tube.

                (this is the vent tube located near the forward area of the primary throttle bores)

                These chemical squeeze bottles are easy and fairly safe to use.



                Now we can fire up "cold" with a full fuel bowl.

                If she fires quickly... then you may have found the reason why other methods are not working well and are inconsistant.

                I do like the Q-jets. They are often misunderstood, and they do have a few little quirks.

                .
                Rick E. Gresham, Oregon
                2850 Bounty Sedan Flybridge model
                Twin 280 HP 5.7's w/ Closed Cooling
                Volvo Penta DuoProp Drives
                Kohler 4 CZ Gen Set

                Comment


                  #9
                  Gents,

                  Thanks very much...very helpful.

                  Rick-I read you post with interest and will do the vent tube fill next time and see what shakes. I love the carb and like I said once she's stated she runs great...I know it's a procedural thing on my part. I'll report back. From my reading it sounds like I should still allow a small crack/opening in the choke plate when doing initial start up. Thoughts?

                  Thanks again.

                  Comment


                    #10
                    "duke1" post=561887 wrote:
                    Gents,

                    Thanks very much...very helpful.

                    Rick-I read you post with interest and will do the vent tube fill next time and see what shakes. I love the carb and like I said once she's stated she runs great...I know it's a procedural thing on my part. I'll report back. From my reading it sounds like I should still allow a small crack/opening in the choke plate when doing initial start up. Thoughts?

                    Thanks again.
                    Yes, probably a bit bigger than a small crack IMO...... unless its freeeezing cold outside
                    Dave
                    Edmonds, WA
                    "THE FIX"
                    '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                    (.030 over-Vortec top end-part closed cooled)
                    The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                    Misc. projects thread
                    https://www.baylinerownersclub.org/f...56-gctid789773

                    Comment


                      #11
                      In my own inexpert opinion you need a pencil width at initial start up.

                      Then when you have it dialed in, mark the pull handle where the start up is perfect.

                      I would not be pushing and pulling the manual knob in and out like crazy.

                      In Florida most guys have the choke wired open.
                      Be good, be happy, for tomorrow is promised to no man !

                      1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                      '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                      Manalapan N.J

                      Comment


                        #12
                        Duke, does your intake manifold offer the well for the divorced choke "helix".

                        If so, why don't you purchase a new helix and the linkage arm, and install it?

                        With the correct parts and when adjusted correctly, the choke plate will close off when cold......., and the vacuum diaphragm will pull it open as necessary during start-up.

                        As the helix warms.... it will automatically reposition the choke plate to full open.

                        The key word here is "Automatic" choke. :whistle:

                        .
                        Rick E. Gresham, Oregon
                        2850 Bounty Sedan Flybridge model
                        Twin 280 HP 5.7's w/ Closed Cooling
                        Volvo Penta DuoProp Drives
                        Kohler 4 CZ Gen Set

                        Comment


                          #13
                          "Chief Alen" post=561940 wrote:
                          In my own inexpert opinion you need a pencil width at initial start up.
                          *****************

                          Hmmm, I'm giving this some thought. I've always use a crayon, but I'm willing to try a pencil. :lol:
                          Rick E. Gresham, Oregon
                          2850 Bounty Sedan Flybridge model
                          Twin 280 HP 5.7's w/ Closed Cooling
                          Volvo Penta DuoProp Drives
                          Kohler 4 CZ Gen Set

                          Comment


                            #14
                            "2850Bounty" post=561975 wrote:
                            "Chief Alen" post=561940 wrote:
                            In my own inexpert opinion you need a pencil width at initial start up.
                            *****************

                            Hmmm, I'm giving this some thought. I've always use a crayon, but I'm willing to try a pencil. :lol:
                            Carpenter pencil! :P
                            Dave
                            Edmonds, WA
                            "THE FIX"
                            '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                            (.030 over-Vortec top end-part closed cooled)
                            The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                            Misc. projects thread
                            https://www.baylinerownersclub.org/f...56-gctid789773

                            Comment


                              #15
                              "builderdude" post=561977 wrote:
                              "2850Bounty" post=561975 wrote:
                              "Chief Alen" post=561940 wrote:
                              In my own inexpert opinion you need a pencil width at initial start up.
                              *****************

                              Hmmm, I'm giving this some thought. I've always use a crayon, but I'm willing to try a pencil. :lol:
                              Carpenter pencil! :P
                              *************

                              Yeah... but on the flat or turned sideways?

                              In very cold climates, I use three pieces of spaghetti.

                              In warm climates, I use an Italian bread stick.

                              .
                              Rick E. Gresham, Oregon
                              2850 Bounty Sedan Flybridge model
                              Twin 280 HP 5.7's w/ Closed Cooling
                              Volvo Penta DuoProp Drives
                              Kohler 4 CZ Gen Set

                              Comment

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