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  1. #1
    Join Date
    May 2009

    Default leaking accelerator pump

    Ive got a 1968 Wildcat with a 430, its got a 750 Qjet that ive rebuilt once, the thing was full of gunk when i rebuilt it but now its totally clean and free of rust or old gas residue. its been running great up untill today.
    had the car idling, gave it some gas and rev'd it for a while untill the enigne back fired. at that point there was a small fire in the left secondary barrel, it burnt out but i started getting alot of smoke out of the exhaust that didnt stop, a couple minutes later the accelerator pump started leaking gas, not a ton, but a sufficient amout to spill onto the intake.
    thought it was mabye a deffective plunger on the accelerator pump so i opened up the carb, there was gas all on the upper gasket around the bowl and pump. the rubber is all fine along with the float needle seat and all that, but the float bowl insert looks slightly shriveled, the sides arent square and its just not sitting flush, there was no new insert in the rebuild kit so mabye its warped over time and gas is getting above it easily? i really have no ideas here, im new to all this and everything i know is what ive learned working on this car, so any ideas would be really appreciated. Thanks! -luke

  2. #2
    Join Date
    Feb 2002
    East Brunswick NJ

    Default Re: leaking accelerator pump

    With the increased ethanol content in today's gasoline, some of the older floats have become damaged from it and no longer function as intended. I'd try a new float that says it is compatible with ethanol along with a new needle and seat. Your symptoms are consistent with a high level of fuel in the bowl.
    Artie Sabatino

    ASE Master Tech w/L1 Certification
    Former "wrench" at Dynotech Performance

    72 Skylark 350 13.94@93.1 Stock engine, stock cam. 3400 Stall TC, Hooker headers, 3" Pypes exhaust, TA Intake, 750 Holley, 1" Spacer
    13.69@94.8 so far with Comp 260H cam

    98 Regal GS - wife totalled it
    Buick powered race car in progress :)
    86 GN Hardtop 11.22@117.9 1.52 60' stock motor with bolt-ons, 3700# with working A/C Sold

    Dyno sheets don't win races...see you at the track
    BPG #1632

  3. #3
    Join Date
    Jan 2008
    Mount Vernon, Ohio

    Default Re: leaking accelerator pump

    Replace the float. I would also install a new needle/seat assembly and one of our modern accellerator pump assemblies. They are Viton and not effected by the new fuel(s). We sell these parts separate from our kits......Cliff


  4. #4
    Join Date
    Feb 2004
    Carson City Nv.

    Default Re: leaking accelerator pump

    To all,

    I believe it is time to address something that appears to be easily overlooked. Gasoline, even in the 1960's, was in a state of flux. Throughout the seventies, emission standards caused numerous issues causing reformulation. As fuel injection came on the scene, gasoline changes became more frequent, and more radical. These included changes in chemistry, vapor pressure, and octane. The resulting experimentation required changes in chemistry, and changes in the hardware and computer software to keep up with the changes. You would be surprised in the changes in computer software alone to compensate for regional differences in "gasoline." Now the point:
    Many do not understand the impact on the carburetor kit manufacturer's requirements that gasoline chemistry has. You can be assured that, if the auto makers are "dealing with issues," you can be sure that the carb kit manufacturers either spend the money or give up. Many will choose to give up, continuing to build kits on 50 year old technology, and not being aware of the ramifications. An educated public is the only solution. Do your homework, research, and don't be afraid to ask questions, and to trust people carrying "specialized" parts, like Cliff Ruggles. These "geeks" are the reasons we are not all running new Holley carbs. These parts, made of higher quality materials, though more expensive, are offset by the needed expertise and time required to install them. This does not mention the possible losses to our valued investments. To wit, the fire this enthusuast quickly recovered from. Imagine the loss if the backfire had burned his prized car to the ground. Food for thought... Ray

  5. #5
    Join Date
    Jan 2008
    Mount Vernon, Ohio

    Default Re: leaking accelerator pump

    Thanks Ray.

    Just to add a few notes, all of the manufacturer's for carburetor "kits", Echlin, Walker, Standard High Grade, etc have failed us miserably when it comes to stepping up kit contents for these new grades of fuel.

    I'm also pretty sure at this point that most of the companies who supply kits are either out of business or have been absorbed by one company, as it matters not where or from who you get your kit, it will NOT contain OEM equivalent parts, and have the needed components inside upgraded for ethanol.

    We made efforts to educate them, and to upgrade the kit contents, with ZERO success. They simply look at carburetor parts as if they are on the endangered species list, not to mention they have thousands and thousands of dollars of "old stock" components to use up BEFORE they would even consider stepping up and making better parts.

    We just went out last month to every local parts supplier and ordered a kit for an early 70's Quadrajet. Every single one came with soft white plastic pump assembly, with a black rubber seal on it. This information is in an article in the current issue of HPP magazine.


    The seal was placed in gasoline (10 percent ethanol), and it swelled to twice it's normal size in less than an hour, and fell right off the pump with little effort!

    The needle/seat assemblies were also much smaller than the OEM parts. We ordered the kit for a 455 engine, and the needle/seat assemblies came with a .125" orifice diameter. The needle did NOT appear to have a Viton tip on it, it was "soft" and black in color.

    In any case, our kits contain complete accellerator pump assemblies, with a high grade fluoroelastomer seal held against the bore by a garter spring. We also supply the retainer, and custom duration/delivery springs.

    Our needle/seat assemblies are the windowed .135" high flow units with Viton tipped needle. We can supply larger or smaller seats upon request.

    Kits also contain dozens of parts NOT found in over the counter kits, including the secondary cam and spring, complete fastener set, float, power piston spring assortment, secondary throttle shaft return spring, idle tubes, plastic collar (metal for 1967 units) for the power piston, good gaskets, seals, small parts, etc. These are the same exact parts we use here in the shop, with zero failures to date, and some customers are running E-85......Cliff

    Last edited by Cliff R; 07-15-2009 at 10:01 PM.



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