small hesitation off idle

Fuel and Air Systems

  1. twotone68

    twotone68 lifetime mopar man

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    Ii have a off idle hesitation,warmed up.185 deg.Just rebuilt a edelbrock #1406/600 cfm. Replaced a very worn out holley 600. It's on my mild 318,stck bottom end,78,00 miles,performer intake,mopar elec.ignition,hughes 318 muscle cam,street carter mech. fuel pump,stock coil,msd wires,5 deg. base timimg, vac. adv. hooked up, carb in excel. shape, all settings set to rebuild kit specs.Edelbrock kit. Any ideas??
     
  2. TrailBeast

    TrailBeast AKA Mopars4us on Youtube

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    Which hole is your accelerator pump set at?
    Are you sure the timing is set ok?

    A little trick I use to see if it's lean off idle is to partially cover the top of the carb with my hand as I start up on the RPM's
    If the hesitation goes away, then it's a lean issue and very probably the accelerator pump.
     
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    • OldmanRick

      OldmanRick Well-Known Member

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      I'm not a expert on tuning the Eddy carbs, and while that may be some of the problem, with the Hughes cam installed, i'd think that engine would be much happier with the initial timing at least up around 12/14* vs the 5* you have it now. And, where is the vac adv hooked to.....ported or full vac? I'd try bumping it up and see how it reacts. You need to get the timing right first, and then play with the carb if need be.
       
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      • KitCarlson

        KitCarlson Well-Known Member

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        +1 on advancing the timing. While adding fuel may help, the real problem is likely in the timing.
         
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        • Bad Sport

          Bad Sport HALF A BUBBLE OFF Staff Member FABO Gold Member

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          And quite possibly a little more. My teen is at 16* initial.
           
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          • twotone68

            twotone68 lifetime mopar man

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            AS per. the edelbrock rebuild kit, the pump rod is in the middle hole. The vac. adv. is at the passenger front. manifold vac.,my timing is with vac. plugged off , have not checked full advance. I have never run base timing on any of my small blocks higher than 9degs.??? I will deffinately check my timing and get back with you all. Thanks.
             
          • 70aarcuda

            70aarcuda Master Hoader of SBM FABO Gold Member

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            remove the caps on the meter rods...fire up the engine...while idling make sure the rods are pulled down and not bobbing up and down...if they are you need to a lighter step up spring...
             
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            • Abodybomber

              Abodybomber Breaking street machines , since 1983.....:) Legendary Member

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              A well tuned distributor curve,more initial timing,quicker response to 3000 rpm total. This involves,tinkering with the curve springs. You throw 12-16 initial timing,you could detonate like crazy. Try it,just don't leave it that high,without shortening the mechanical advance.Good Luck!
               
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              • pjc360

                pjc360 Well-Known Member

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                Start the engine, let it warm up until operating tempature and then take a can of carburetor cleaner and spray around the throttle shaft on both sides of the carburetor.
                And I bet you the idle will smooth out, Indicating a vaccum leak. The edelbrock carburetors are infamous for worn out throttle shafts bores, which in turn causes big vaccum leaks, and a big vaccum leak will cause the hesitation you are describing.
                 
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                • Oldmanmopar

                  Oldmanmopar Going left turning right FABO Gold Member

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                  One thing that most do not do when adding a 4 bbl. and a cam to a 318 is upgrade the distributor vacuum advance. 340. are different and operate with less vacuum do to cam an 4 bbl.
                  On the arm coming from the vacuum advance in the distributor there is a number. 11.0 is a 318 360 2 bbl. advance. 8.5 is 340 360 4 bbl.advance. All are also adjustable with a allen screw inside the vacuum port. take off the hose and use the correct size allen wrench inside the tube. This controls the amount of travel and the force needed to move it.

                  Just some info you can use to fine tune for maximum performance.
                   
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                  • twotone68

                    twotone68 lifetime mopar man

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                    Here's my results!!!!My 68 dart,318,904,3.21 7 1/4. Just had the edelbrock carb rebuilt and installed. I checked the timing. Base was 5 deg. which gave me a full of 26 ??? I moved it up to full of 35 and base of 9. My vac. advance hoes was going to metered vac. switched it to ported/manifold vac. reset air/fuel and idle.Now idle quality is much improved{Hughes cam is heard now!!} Hesitation is completely gone !! And from a dead stop it will SMOKE the rt. rear tire all the way through 1st. and 2nd. gears !!! About 50-60 feet!!Thank you to all for your advise an suggestions !!!! FABO RULES !!!!:D
                     
                  • OldmanRick

                    OldmanRick Well-Known Member

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                    Glad you had positive results. Enjoy your Dart. :thumbrig:
                     
                  • Abodybomber

                    Abodybomber Breaking street machines , since 1983.....:) Legendary Member

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                    Cool.
                     
                  • Blainethemono

                    Blainethemono Well-Known Member

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                    This is an update for Carter Ball and Ball 1 bbl Carbs, Models BS-4099S, 4100S, 4103S, 4104S, & 4172S Model Numbers. The Accelerator Pump has a LEATHER gasket, NOT Rubber!!. You MUST oil this gasket before assembly or the pump MAY NOT WORK!!

                    Here is a link for a new one.

                    Carter BBS Accelerator Pump 5/8 x 2.340

                    Carter bbs1.jpg
                     
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