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Dead spot in Edelbrock Carb

Discussion in 'The Garage' started by mountainexplorer, Dec 10, 2003.

  1. mountainexplorer

    mountainexplorer 1/2 ton status

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    I put a fully functional Edelbrock 750 carb on the 454 in my Crew Cab today since my Q-jet was acting up. Right off idle, when you slowly increase the throttle, it hesitates and almost sputters (even worse when actually driving and taking off beings it's a 4spd).

    Theres a certain spot where the hesitation goes away and it suddenly revs up a bunch higher and becomes smooth. Just below that point it runs bad, and above that point its fine.

    Could it just need a rebuild? Or could there be other spark issues? (Ive replaced almost everything except the ignition module)
     
  2. TopOff

    TopOff 1/2 ton status

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    Could be jetting.

    Could be a bent rod (carb)

    could be ignition advance.

    Could even be junk in the carb. These carbs are NOTORIOUS for being picky with just about ANYTHING dirty in them.

    I tried those glass filters... CRAP! Get a F.I. based filter.

    Good luck.
     
  3. 88Silverado

    88Silverado 1/2 ton status

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    I dont know if you have the Q-jet replacement or the standard Squarebore carb?
    I have the Edelbrock 1406 squarebore on my car. It had a bad hesitation off idle etc. Basically its a Lean condition. You can try to move the accel pump cam one notch higher to squirt more fuel in faster or you may need to change the springs for the metering rods. Thats a super-simple change. Not sure about the Q-jet design.
     
  4. Z3PR

    Z3PR Banned

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    Edelcrap.
     
  5. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Let's remember that is just your opinion. /forums/images/graemlins/thinking.gif I have a couple E-brock carbs and love them.. They work fine in my applications. /forums/images/graemlins/thumb.gif

    To the original subject on this. I'll second the acc. pump cam thingy. /forums/images/graemlins/smile.gif

    John
     
  6. mountainexplorer

    mountainexplorer 1/2 ton status

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    It's a 750 CFM Square bore... 1409 I think. (Correction- 1407)

    I'll give the accelerator pump adjustment a try. Thanks. /forums/images/graemlins/thumb.gif
     
  7. 88Silverado

    88Silverado 1/2 ton status

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    Go to Edelbrocks site. They have calibration curves listed for the squarebore carbs. 1409 calibration chart and Tuning Procedures

    I actually like my Edelbrock for street. It doesnt do all that well on mileage but its so damn basic and simple to adjust you cant beat it. Its basically a copy of a Carter AFB built by Weber. /forums/images/graemlins/thumb.gif
     
  8. JDBlazer454

    JDBlazer454 1/2 ton status

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    Thanks a bunch for those sites 88.

    I have found that the 750's are way more picky then the 600's I have had. But they are good reliable carbs that require very little maintenence once dialed in.
     
  9. NITRO

    NITRO 1/2 ton status

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    sounds to me like it could also be the 2 screws on the front of the base of the carb. i think they are supposed to be 1 1/2 turns out to start with and go from there. that sounds like what mine was doing, and those 2 screws fixed it.

    NITRO
     
  10. mountainexplorer

    mountainexplorer 1/2 ton status

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    I tried making a bunch of adjustments anywhere I could externally on it. Still didnt change the hesitation/dead spot. So, I got a 1406 (600 cfm I think?) from my friend, stuck it on there, and the hesitation is gone. I'm expecting to have to rebuild the 750.
     
  11. florida4x4

    florida4x4 1/2 ton status

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    sounds like the idle transition ports have crap in them. might be able to clear it by revving up the engine and stuffing a rag into the choke housing.. dont loose the rag down the intake though /forums/images/graemlins/crazy.gif
     

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