Announcement

Collapse

Get more Tips, Specs and Technical Data!

Did you know... this Forum is a service of the Studebaker Drivers Club? For more technical tips, specifications, history and tech data, visit the Tech Tips page at the SDC Homepage: www.studebakerdriversclub.com/tips.asp
See more
See less

Very rough idle when cold

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Engine: Very rough idle when cold

    My Avanti II, 350, is starting to idle very poorly when started in the morning...lots of grey smoke to start. Once she warms up a bit she runs fine. Choke issue? Ideas?
    Lou Van Anne
    62 Champ
    64 R2 GT Hawk
    79 Avanti II

  • #2
    Still have the Rochester Quadrajet? The float may be getting saturated and thus need replacing.

    Comment


    • #3
      Don't know the history of your particular Q'Jet, but this article may enlighten you as to the old age problems to consider. The black-grey smoke indicates, to me, that you have excess fuel dripping and accumulating in the intake-once warmed up it minimizes enough that the mixture is "tolerated" by the engine. I think a total rebuild, including many of the suggestions in the article will get you back on the road for a long time-good luck. http://www.superchevy.com/how-to/eng...tretor-tuning/

      Comment


      • #4
        You could pull the spark plugs and see if they are all the same color. If one is perfectly clean, that cylinder has coolant leaking into it.
        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

        Comment


        • #5
          Too much choke....May also need an idle speed adjustment. (higher)

          Comment


          • #6
            When I worked at the GM dealership in the 70's and early 80's there was a fix for the quadrajet for fuel leaking.
            I installed a lot of foam pads in the recess pocket, but I'd bet those foam plugs may not hold up to today's corn crap gas.

            Comment


            • #7
              Before going for a full rebuild, or assuming there is something internally wrong with the carb, you need to check that the choke pull-off is working. There are many different styles, and they normally will ALSO control the secondary opening. It is sometimes referred to as a vacuum break.

              Always start with the easiest thing to check.

              Pull off the vac hose; if you have a vac pump, check to see if it holds vac (or even works at all... I have seen them so bad they don't even respond to vac.) If you don't have a small vac pump, just attach a length of vac hose long enough to suck on it with your mouth. Pull it down with the vac from your mouth, put your tongue over the end of the hose and see if it holds vac. If not, that is likely your culprit.

              Comment


              • #8
                Believe Lynn nailed it! i have seen this problem before in a previous life as an independent garage mechanic, flooding all the time check float and plugs under main fuel passages,there are cures for both. Luck Doofus

                Comment


                • #9
                  Also if you are running Champion plugs, once they foul out they are worthless. Replace them after fixing the choke pull off.
                  Bez Auto Alchemy
                  573-318-8948
                  http://bezautoalchemy.com


                  "Don't believe every internet quote" Abe Lincoln

                  Comment


                  • #10
                    T W Champ is 100 % correct about the plugs leaking

                    Comment


                    • #11
                      The Quadrajet on my 70 always leaked, the mileage was terrible, but with those huge rear barrels, the performance was great. When the gas crisis hit in the mid 70's, I needed to do something as this was a daily driver. What I found was a Holley replacement carb that made the engine run like a sewing machine. The name was a Holley Economizer, designed to replace the Quadrajet and around 450 CFM. It didn't have those end bowls like the usual Holley and never gave me a bit of trouble. I may even still have it in the stash...
                      64 GT Hawk (K7)
                      1970 Avanti (R3)

                      Comment


                      • #12
                        Remove the carb. Remove the base plate from the carb. Turn the main body over. In the bottom of the main body you will see four small soft lead plugs. Seal over these plugs using a two part epoxy. Allow 24 hours to dry. If you put it on too thick, you may have to file a little off. Reassemble. I did this hundreds of times in the 70's and 80's.
                        61 lark cruiser
                        64 daytona 2dr hardtop

                        Comment


                        • #13
                          I am not saying the well plugs don't need repaired. However, not knowing the history of the carb, there is every chance they have been. I just reparied a set on my 68 El Camino last week.

                          However, the immediate issue faced by the OP indicates a choke pull off issue. "Once she warms up a bit she runs fine."

                          Q-jets with badly leaking well plugs won't idle properly when warm.

                          Comment

                          Working...
                          X