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Help tuning Edelbrock 1406 carb

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by MikeH, Apr 26, 2001.

  1. MikeH

    MikeH Registered Member

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    Monument, CO. USA
    Recently replaced my Holley with a new edelbock 1406 carb for mileage/driveability reasons. The mileage has increased a couple of mpg but still need tuning help.

    There is a hesitation when I gradually step into the gas. If I depress the pedal quickly, no hesitation occurs. This occurs at all engine speeds but is most noticable (of course) from a standing start.

    Once I get the edelbrock tuned right I think I will like it a lot more than the old holley is was running.

    Engine info

    Newly rebuilt 383 stroker small block (1000 miles). HiPo everything. Will be supercharging it later this year....

    Thanks
     
  2. californiak5

    californiak5 1/2 ton status

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    I can't help with the tuning, but I am very curious about the answer. I am putting the same carb on my truck real soon and any info would be great. You may want to post this on the 73-up board. There are alot of motor heads there.

    See Ya,
    Keith

    [​IMG] <font color=green>Born to Drive My K5</font color=green> [​IMG]
     
  3. Steve_Chin

    Steve_Chin 1/2 ton status

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    You either need more pump shot or your low end mixture is too lean. I believe Edelbrock has jetting kits for this carburetor, but first try to slightly enrich the idle circuit to see if the problem doesn't go away.
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Steve,

    Do you have a recommendation on a local Bay Area shop that can do performance tuning? Ideally, I'd like to find a shop with a chassis dyno, so I could get some hard numbers....especially before/after #'s.

    It would be great to get the carb setup (linkage, jetting) and confirm the correct timing, and advance curves, etc.


    -Greg72
     
  5. clarkekent

    clarkekent Registered Member

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    Check out the edelbrock website ... they have all kinds of tuning info available for any carb they make on it.
     
  6. Ryan_B

    Ryan_B Registered Member

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    You know that speed merchant on Lincoln right off of San Carlos, has a chassis dyno, that supposedly measures up to 800 HP. They unbolt the back tires and bolt up your axles to the dyno machine, so there is no slippage.
    My buddy had his '69 Camaro dyno'd there, but they wouldn't let him pull the engine. One of the guys who works there *had to drive* the car on the dyno. I think a little persuasion and maybe a little more money and they'll let you pull it yourself.
    I think the charge is around $80 for 3 pulls, and something like $80 per hour of tuning after that. I think they have tech's that tune your engine to get max. performance.
    Give em a call and they'll let you know for sure.

    My 2 Cents.
    Ryan
     
  7. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Ryan,

    Yes I've seen that place...I just had a weird "gut feeling" for some reason about that shop. I can't explain it but it just seemed to have too many young kids hanging around, and I got the feeling that my K5 might not be treated with the kind of professionalism and experience, that I would be paying for.

    They may be a great shop, and if your friend with the Camaro had a positive experience I will re-consider bringing my 'baby' there. First impressions can be hard to shake sometimes [​IMG]

    -Greg72

    "I'd really love to know what my real HP/TQ numbers are..."
     
  8. Tonka

    Tonka Registered Member

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    I put a 1406 on my basically stock 350 a couple years ago and it is serving me well. If I remember correctly though, I had the same problem. The 1406 is factory calibrated for economy. The 1405 is the same carb (maybe diff. choke setup) but is calibrated for performance. I wasn't happy with the performance of my 1406 until I had jetted it the same as the 1405. I would guess that youre just too lean with the 1406, especially with any type of performance cam in the 383. Also, I agree that the pump shot makes a big difference. Try the middle hole in the pump arm.
     
  9. Steve_Chin

    Steve_Chin 1/2 ton status

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    G-F Automotive in South San Francisco. They are not cheap, but they do a lot of work on autocrossers and road racers. The owner's a friend of mine, but he's been seriously ill, so you likely won't get to talk to him. I haven't used their chassis dyno yet, but it is something I've been planning on doing to do some touch-up tuning on my T/A. Just too many other things to do at the moment.

    Anyhow, you might also want to check with Frey Racing in Milpitas. They do almost zero work on street cars (all they do is race cars), but you might be able to get some dyno time there. Hmmm... I'm wearing one of their T-shirts today. LOL!
     
  10. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Thanks Steve! I'll check those places out. And of course, if I get cool data I will post it for everyone to see and enjoy.

    ....I just knew you'd have the "info" I needed. [​IMG]

    -Greg72
     
  11. JST12

    JST12 1/2 ton status

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    MikeH,
    In the Edelbrock tuning guide it says the following below. Maybe this is your problem.
    ----------------------------------------------------
    If your vehicle has a mid-throttle driveability problem that is encountered as the throttle is gradually opened, but then goes away upon further opening, it may be possible to eliminate the lean spot by using a stronger Step-Up Spring. The available Step-Up Springs are listed in the following chart along with their respective "staging" point. It is best to select a new spring on the basis of vacuum readings, but in the absence of a gauge, try the strongest spring (highest vacuum rating) to see if the problem goes away. If the drive problem is cured by the strong spring, try the next weakest spring as well. If the strong one does not help, then the calibration problem is related to the A/F metering stage of either the Cruise or Power Modes. Use the Calibration Reference Chart to help select another combination.

    Spring Color Blue Yellow Orange Pink Plain
    Staging Vacuum ("Hg) 3" 4" 5" 7" 8"


    A complete set of these springs is available separately as Edelbrock part #1464.
     

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