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Thread: Acceleration Problem - 4160 & 3/4" Spacer

  1. #1

    Default Acceleration Problem - 4160 & 3/4" Spacer

    Newbie here & sorry for being long winded. Hello, my name is Marvin & I'm having a little bit of acceleration/cutout problem while starting out from standing start. If I take it very slow it's OK, but if I give it more gas, it feels like it's getting too much gas & just for a short time, it cuts out for a second & then all is OK.

    Vehicle is '68 Chevy C10, 305, 700R4, Holley 4160 with 3/4" spacer, manual choke, HEI distributor with Accel super coil #140003. Nothing fancy, just how it was bought. Past owner has "rigged" up the TV cable with bailing wire & a lot of slack in the cable. I do know that needs to be fixed, cause it goes through the gears real fast like 0-25, at that point it's in 4th. Don't know why the 3/4" spacer was installed, but first things first. I know, baby steps, right. Any help in the right direction will be appreciated. mjgord51

    Click image for larger version. 

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  2. #2

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    Normally this is an issue with your accelerator pump linkage and linkage cam setup. If there is any play in the linkage, it will not give a quick shot of fuel, and causes bogging/hesitation. Air reacts quicker then fuel can. This is the purpose of the accelerator pump. To provide a short pump of gas as you move the throttle. It gives fuel time to react to the air you are suddenly introducing, by opening the throttle blades. You need to get your accelerator pump linkage setup so that as you barely bump the throttle you see fuel coming out the pump nozzle. I wouldn't mess with the pump cams just yet. Get you linkage adjusted properly first then test.
    Below is a quick video on how to get that adjusted properly:
    https://www.youtube.com/watch?v=k-Nx5HEzvlY

    Something I have seen, is the lever that rides on the pump cam will have a slight gap between the lever and the cam. Make sure the lever is resting directly on top of the cam so that as you move the throttle, it's moving instantly. If there is a gap you cant get out, take the pump cam off, and bend the lever down ever so slight. Just enough to get the lever to rest on the pump cam with no gap.
    Last edited by 69cam; 08-12-2015 at 03:42 AM.

  3. #3

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    I'll give it a shot on the weekend I hope. I have some health problems that restrict my movements from time to time, I'll do my best and will get back to the forum as soon as possible. Thanks 69cam.

  4. #4

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    I know you all thought I would be right back, didn't you. Well here we go again. STILL having pretty much the same problems with the stalling from coming off the line, but also now having stalling when pushing hard on the throttle at 40-50 MPH in top gear at this point. HERE'S what has been changed so far. The carb now has a new Trans Kickdown/TV Extension for the Correct Geometry, and new Throttle/Kickdown Cable Bracket (modified) delete throttle cable bracket Cut Off with leaving just the TV Cable Bracket. I have found that the Accelerator Pump Lever "Spring" doesn't seam to be right being it fitting SLOPPY. I did shim it with small washers, but I don't think it really did much good (maybe just a little) in adjusting it as needed correctly. I've read that the Accelerator Pump Cams & Accelerator Pump Nozzle might need changing to other sizes. One more thing bothering me about this carb is that the Manuel Choke cable doesn't line up, or it's not on the same plain where the cable mounts to the carb and where the cable stop is, kinda dog legs a little. I'll try and post a picture of the misalignment of it. Thanks in advance, Marvin.
    Attachment 2001

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