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Technical Edelbrock question

Discussion in 'Traditional Hot Rods' started by pull toy, May 18, 2021.

  1. pull toy
    Joined: Aug 22, 2013
    Posts: 84

    pull toy
    Member

    I have a Edelbrock 1405 Performer carb that has a less than strong accelerator pump discharge. This is a fairly new unit. Upon examining the carb I find that with the design dimension of 17/32 inch ,which is the dimension from top of the pump shaft to the air horn top in the rest position in the middle linkage
    hole, the pump head is 1/4 inch below the bottom of the vertical slot in the pump chamber. I have always believed that this vertical slot was there to allow fuel to run into the pump chamber under the pump head to set up for the next squirt. Talked to big people at Edelbrock and no one knew anything of this condition. Even with the pump completely detached from linkage the pump head will still not come up above the bottom of this vertical slot..... Has anyone discovered this before.
     
    Chucky likes this.
  2. The accelerator pump plunger acts as a check valve. On the up stroke (when the throttle is released) the fuel can flow into the accelerator pump well past the plunger. On the down stroke the plunger seats against the plunger stem like a check valve and the fuel is forced through the passage and out the accelerator pump nozzles.
     
  3. Mr48chev
    Joined: Dec 28, 2007
    Posts: 30,185

    Mr48chev
    Member

    Looking at the floats in comparison to the accelerator pump how far is the fuel level above that slot if it is above the slot? It looks like it serves as much or more as a vent for the air above the accelerator pump piston as it does for allowing any fuel in. Hooptie_Rebuild_Shoot_Two81-vi.jpg Edelbrock carb body (2).jpg
     
    Hamtown Al likes this.
  4. Nick Nadol
    Joined: May 18, 2021
    Posts: 14

    Nick Nadol

    Never really a big fan of edelbrocks carbs.
     

  5. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,229

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    And that is relevant how?

    Ray
     
    alanp561, JeffB2, Just Gary and 12 others like this.
  6. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,472

    Mike VV
    Member
    from SoCal

    Then why comment on something that you don't know about, and don't care to know about..?
    And if you're gonna bad mouth something, at least have respect to capitalize the mans (Edelbrock) name .

    Mike
     
  7. Check out video starting at 11:06. Does this help at all?
     
    Scumdog likes this.
  8. Joe Travers
    Joined: Mar 21, 2021
    Posts: 485

    Joe Travers
    Member
    from Louisiana

    Have you tried changing pump rod setting & squirter? Not stated.

    Joe
     
  9. Thanks for sharing your unsolicited opinion of the brand with us, but it lends absolutely no substance to the OP's inquiry.
     
    JeffB2 and '49 Ford Coupe like this.
  10. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,783

    6sally6
    Member

    Pull toy......is there an issue with the Edelbrock(which I happen to LIKE!):) on your engine OR is this just an observation while tuning on the carb?
    IF enough fuel is NOT being delivered with the acc. pump set on the highest position....maybe ignition/jetting/size of carb may be the problem!
    What's it do'in?!!
    6sally6
     
  11. Yeah but now he's got enough posts to contact that guy in the classifieds about that badass Holley with the leaking throttle shaft and horrible dead spot!! Ford, Chevy, Edelbrock, Holley, who cares run what YOU like! Victor Edelbrock invented gasoline, Not Holley :rolleyes::p:D
     
  12. I’m more an old school Carter kind of guy...


    I just thought I should add my own useless post to the thread.

    Sent from my iPhone using H.A.M.B.
     
  13. pull toy
    Joined: Aug 22, 2013
    Posts: 84

    pull toy
    Member

    Yes have it now in the top hole [of the three]. As stated the squirts are there but not strong and of long duration. Some fuel is getting below the pump head to recharge the squirt but not enough.
     
  14. sdluck
    Joined: Sep 19, 2006
    Posts: 2,806

    sdluck
    Member

    Looks like there is a lot of crap in the fuel bowls.
     
  15. saltflats
    Joined: Aug 14, 2007
    Posts: 11,037

    saltflats
    Member
    from Missouri

    The cup on the pump should never come above that slot when the carburetor is assembled. If it did during normal use it would wear out the cup trying to make the gap.
     
  16. pull toy
    Joined: Aug 22, 2013
    Posts: 84

    pull toy
    Member

    Thanks, yes my engine when dumping the pedal will hesitate slightly and many times will back fire [hard] through the carb, this indicated a lean mixture. All distributor internals are new, new plugs & wires. Timing has been tried at every level. The carb has about 3000 miles on it. Another thing I found the floats were set high, have made adjustments. Edelbrock tech recommended changing rods to reflect a smaller dia for power and a larger dia for cruise, that will richen up the power this is being done. Let me say Smitty with Edelbrock is one heck of a great guy to talk with, he is all in to help solve issues but they have no answers about the pump head living below the pump well slot. I have set the linkage in the top of the three holes giving me a little more stroke. Have not completed the reinstallation since the new rods have not arrived but an anchoes to see it things improve
     
    Hamtown Al likes this.
  17. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,078

    gimpyshotrods
    ALLIANCE MEMBER

    People wonder why I never bost build threads here.
     
    warbird1 and fauj like this.
  18. pull toy
    Joined: Aug 22, 2013
    Posts: 84

    pull toy
    Member

    That has to be the way it works even though there in no head pressure on the fuel encouraging it to flow past the pump rubber.
     
  19. pull toy
    Joined: Aug 22, 2013
    Posts: 84

    pull toy
    Member

    yes
     
  20. Joe Travers
    Joined: Mar 21, 2021
    Posts: 485

    Joe Travers
    Member
    from Louisiana

    Do you have another pump rod to compare with the new one?
    I wonder if it may be bent, not allowing correct travel.

    Joe
     
    Last edited: May 18, 2021
  21. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,078

    gimpyshotrods
    ALLIANCE MEMBER

    He joined today, has just 14-posts, with an average of three words.
     
  22. Baumi
    Joined: Jan 28, 2003
    Posts: 2,801

    Baumi
    ALLIANCE MEMBER

    I´v had the same problem on a used 1406 Edelbrock that I bought for my wife´s 53 Suburban. It would stumble under acceleration from idle to cruise mode. It improved after the engine had warmed up but cold it would pop and backfire by blipping the throttle. I found it must have been on a engine with a real hot cam at one point, because it had the absolutly weakest primary circuit springs in there. She has a stock 327 cam in it, so I tried to go back to factory Edelbrock specs, which did help, but not fully cure my problem with my wife complaining, hahaha, so I went with the hardest set of spings in the calibration kit . Problem solved!
    Now it´s still too lean and will still pop at full throttle over 4500 rpm, but that keeps her from speeding I hope....
     
    Algoma56 likes this.
  23. Mr48chev
    Joined: Dec 28, 2007
    Posts: 30,185

    Mr48chev
    Member

    No doubt that he has either posted some over priced thing in the classifieds or replied to someone's post of something for sale.
     
  24. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    56sedandelivery
    Member Emeritus

    I have seen a few of the Carter/Weber/Edelbrock, "AFB" type carburetors that had the accelerator pump wells scored up, thereby losing pressure at the "squirt". The top opening of the accelerator pump gets dirt and crud deposited on top, and finds it's way into the well, scratching the walls up, causing the pressure leak. Has anyone come across/heard of a repair kit for this? Is the well scored up pull toy? I am Butch/56sedandelivery.
     
  25. In my opinion that's the worst part of the Carter/Edelbrock afb design, the pump shot is weak and there's no real way to improve it.
    I always describe the carb to roll into the power vs. the strong hit associated with a Holley. I have read about removing some weight from the secondary door weight to get them to open sooner which would make it feel stronger down low.
     
  26. pull toy
    Joined: Aug 22, 2013
    Posts: 84

    pull toy
    Member

    Center of the Galixie member hit the answer on his post I believe. In addition I discovered that the pump chamber in really bored in a slight tapper, meaning the upper portion at or just below the vertical slot is larger in dia than the lower portion. When the pump head is at the idle position the rubber skirt that does the work is not sealing against the chamber walls, as it will be when pressed down, thus allowing gas to flow by it into the chamber bottom. Maybe not the best design but that's how it works. Please note that Edelbrock carbs are set up rich for cruise but not for power. My plugs were smutty but my motor stumbled at power. My factory metering rods were 7047, Edelbrock had me change them to 7342 which means the power stage would be richer while the cruise would be leaner. Springs were also changed to silver at their direction. I now do not believe any carb is a bolt on happy ending situation, they all must be fine tuned to each individual condition. Thanks for all the input.......
     
    alanp561, Algoma56 and Baumi like this.
  27. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,783

    6sally6
    Member

    I did this on my old "M-word" 5.0 engine and WOW! what a huge kick-in-the-scrotum when the secondariess pop open!!
    (It brings to mind the old quadra-jet when the secondaries kicked in.!)
    You DO need to start off removing just-a-little weight (start with a small whole).
    I'm glad I did!!!
    6sally6
     
    swade41 and Deuces like this.
  28. FityFive
    Joined: Aug 9, 2010
    Posts: 319

    FityFive
    Member

    6Sally6,

    What size hole would you recommend starting with (1/16”)? What size did you end with?
     
  29. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,783

    6sally6
    Member

    I'll hafta measure 'em.........I been out-of-town to an "M-word" get-together in Texas!
    6sally6
     
  30. Scumdog
    Joined: Mar 3, 2010
    Posts: 627

    Scumdog
    Member


    Very handy, thanks for posting it!
     
    Hotrodmyk likes this.

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