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Thread: 3310-3 carb. Hesitates when accelerate.

  1. #1
    sabelstrom Guest

    Default 3310-3 carb. Hesitates when accelerate.

    I dont know if this one sould be under steet carbs, if its the wrong place can Admin move it to the right place.

    Hey. I have a problem.

    I have a Holley 3310-3 carburetor and I have replaced and cleaned everything in it.

    I have used a Holley trick kit and some other new parts.

    Now the problem, the car hesitates when I want to accelerate a half second to two seconds, depending on speed, speed and how much I press the accelerator.

    I have tried various nozzle pump discharge 25-38, but the problem is not solved.

    When I compiled the carburetor again, I used the thinnest spring to the secondary membrane, the problem might be that it opens too early.

    I do not use a check ball, because I read on the internet that it would work correctly, and nowhere could I find if it was the big or the small ball that came with the trick kit I would use.

    I have installed a wideband lambda sensor and the idle is about 11afr and it is rich all the way to 80-90km / h then it is about 14.7afr, if I go faster, it becomes richer again.

    But when I accelerate the value goes up to 20afr and the engine hesitates.
    This means too much air or too little gasoline.

    I use 95 octane gasoline.

    Engine chevy 327 from 1967 with headers and x-pipe.

    Excuse the language.

    Anyone have a clue?

  2. #2
    sabelstrom Guest

    Default

    Liz on Facebook gave me some answer:

    "Make sure your timing is correct. Rule out any vacuum leaks. Make sure you are loading the engine at or above the minimum rpm rating of your cam. Make sure that you final drive ratio is compatible with your cam operating range. Make sure the carburetor is not too large for your application then start the proper carb tuning process.



    The first thing that you need to do is insure a solid base line for the carb. I would install an orange cam in the #1 hole. A .031” shooter and a plain secondary spring. Your carb requires a .186” restrictor ball in the secondary housing. As se level install 72 jets and tune from that point.



    Start by adjusting your float level, no fuel should run out the sight plug with the engine running. and check to make sure that your fuel pressure is not over 7 PSI. I suggest 6-6.5 PSI Make sure the accelerator pump is properly adjusted. It should be at zero lash at idle. and have at least .015" gap at Wide open throttle with the pump lever pushed all the way down.



    Next try turning in the idle air screws all the way in with the engine running . If the engine continues to run with both screws all the way in, then the carb is letting fuel into the engine from someplace other than the idle circuit. We have to find out where from and correct it (with the screws all the way in the engine should die) Next you want to check the manifold vacuum with the engine idling in gear. This will tell you which size power valve to use. If your vacuum is 11" and under divide by two, and that is the size you need. If it is 12" and over use a 6.5 PV. You may have to replace it with the correct size. If you get all of this corrected and the engine still runs rich then you will probably have to remove the carb and adjust the secondary throttle plates open to the bottom of the transfer slots. This will allow you to close the primary plates down some. If either plates are open too far then fuel will be pulled in to the engine from the transfer slots in the base plate. By adjusting those plates like I said, the carb will get the same amount of air at idle, but it will get it evenly from the front and rear instead of just the front. Once you get it so the engine dies with the idle air screws, then you can continue with the rest if the adjustments.



    Next you need to adjust the idle air screws. Turn them in until they seat lightly then back them out 1.5 turns. Start the engine and let it warm up. Hook up the vacuum gauge to manifold vacuum. Check it at idle in gear. Adjust the idle air screws evenly until you get max vacuum (the vacuum will drop off if you go to rich or lean)



    With that done you can start working with your jetting , Unfortunately I can't tell you how to jet it. Each engine is different and has different requirements. It is a trial and error process. Start with the stock jetting and go from there, Run the engine under a load and read the spark plug color to find out which way you need to go. Black is rich and white is lean. It is best to tune the primaries first at part throttle and the secondaries at WOT run the vehicle at least a quarter mile and shut it down under throttle in order to get an accurate plug reading. This should be accomplished on a track or a long stretch of road with a wide shoulder that it can be done safely. Adjust it until you get a nice light brown color on the porcelain of the plug.



    When dealing with a vacuum secondary carb keep in mind that they will not open in park or neutral. The engine must be under a load. Place a paper clip on the secondary rod horizontally and slide it up to the base of the secondary diaphragm housing. Drive the vehicle under full load and check the position of the clip. if it is pushed down they are working. If not check the diaphragm and gaskets for damage and clean the vacuum ports. Also keep in mind that they may not open if the carb is too large for the engine or if the spring is too stiff. To increase the secondary opening speed install a lighter spring. Starting with the plain and spring drop one size at a time. if you can feel the secondary ( Kick) you have gone to light and need to go back up to a stiffer spring.



    Once you get this adjusted , If you have an off line hesitation that is less than a second Increase the shooter by one size. If it is over a second increase the shooter by Two. If it makes the hesitation better you can increase accordingly if it gets worse drop the size."






    And this is my answer, haven heard from her since.

    Thanks for your help Liz.



    A lot of progress but also a step back.



    I use a carburetor on a Chevy 327 standard from 1967

    I've used it before on this engine, but the base plate was leaking from the throttle arm so I decided to renovate it.



    Some figures.

    Engine: 3782870, 327, 62-67, 250-375hp, Car & Truck 2-bolt.

    Cylinder heads: 3774682, 283/327, 60-67, 1.72/1.50 valves (5, k2560, GM 3, T, C).

    Manifold: Edelbrock performer.

    Transmission: Standard 350 machine.

    Car and rear axle: Buick Skylark Custom 4D HT 1970

    Fuel pressure: 6.2 PSI.

    Vacuum at idle in gear: 15.5 in-Hg (400KPA, 54mm -Hg).

    Shooter: Tried with 031" but it went better with the 037".

    Exhaust: Headers 4-1 3" and 2.5"x-pipe, the rest 2.5".



    Fitted the 72 jets and the orange cam in hole #1.

    Fitted a standard spring with the secondary diaphragm and the check ball.

    What is new in the carburetor is the base plate, the secondary diaphragm, all gaskets and everything else that came with The Trick Kit 37-933. Had also a Renew Kit 3-754 that I could use.



    The maximum rpm and the vacuum was measured when the idle air screws were screwed 1.0 turns.



    The car does not hesitate anymore when accelerating. That's good



    Now the new problems.

    I can not find any numbers on the Power Valve but I do not know if it is sent various Power Valves or not in the kits.

    The engine does not die when you turn in the idle air screws.

    The engine runs very rich the whole register about 11.5-12.5AFR.



    If I chose the smaller main jets would I get the AFR value up then? or the solution is what you wrote in the previous post

    "If you get all of this corrected and the engine still runs rich then you will probably have to remove the carb and adjust the secondary throttle plates open to the bottom of the transfer slots. This will allow you to close the primary plates down some. If either plates are open too far then fuel will be pulled in to the engine from the transfer slots in the base plate. By adjusting those plates like I said, the carb will get the same amount of air at idle, but it will get it evenly from the front and rear instead of just the front. Once you get it so the engine dies with the idle air screws, then you can continue with the rest if the adjustments."

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