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Hot Rods Any Edelbrock carb guru's on here?

Discussion in 'The Hokey Ass Message Board' started by Doug520, Apr 3, 2020.

  1. Doug520
    Joined: Apr 21, 2016
    Posts: 25

    Doug520
    Member

    I've always had Holley's. However, my 1930 Model A coupe has a ZZ4 small block Chevy with an Edelbrock carb. There are no carb numbers on mine, as I'm told that the Endurashine versions like mine didn't come with them stamped into the base plate like the non-Endurashine carbs have. I guess I need to start with finding out what series Edelbrock carb I have. I'll try to attach a photo on here, maybe (hopefully) someone can ID the series type visually.

    Here's the issue - the car runs very well, UNTIL I try to mash it from a stop or a slow roll. Then it spits out the carb and dead stalls. It's pretty severe. I moved the accelerator pump to the top hole, but that didn't help. In reading on line in an attempt to learn this new to me Edelbrock carb world, there's lots of Edelbrock carb terminology used that I'm not familiar with.

    It sounds to me like the secondaries might be flying open to quick, but since there is apparently no secondary accelerator pump to feed that action with appropriate amounts of fuel, the only way to fix that would seem to me to be to somehow slow down the rate that the secondaries open. How in the world do I do that? Am I on the right track here with this theory? The primary and secondary mixtures seems to be pretty much on, I have no issues with the way it runs except for the severe spit and stall at abrupt WOT.

    Any ideas on what carb I have and how best to deal with this issue?

    Thanks, guys - I hope I can get the photos to post here.
     

    Attached Files:

  2. Flathead Dave
    Joined: Mar 21, 2014
    Posts: 2,877

    Flathead Dave
    ALLIANCE MEMBER
    from So. Cal.

    No answer for you here, but the pic on the upper right looks like the robot from "Bill and Ted's Excellent Adventure"...Most Excellent!
     
    Deuces likes this.
  3. I'm more of a Holley guy myself, but I'm pretty sure there is an adjustment to vary the timing of the opening of the secondary air valve. It's pretty simple just loosen a screw and change the tension on the spring that controls the air valve. Edelbrock may be able to supply tuning information that would be more precise than what I have to say.
     
    Deuces likes this.
  4. fastcar1953
    Joined: Oct 23, 2009
    Posts: 2,126

    fastcar1953
    Member

    Best guess it's a 600 cfm with electric choke. 1406 model . Try switching vacuum advance to driver side.
     
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  5. fastcar1953
    Joined: Oct 23, 2009
    Posts: 2,126

    fastcar1953
    Member

  6. Mike VV
    Joined: Sep 28, 2010
    Posts: 1,917

    Mike VV
    Member
    from SoCal

    Nope..!
    Only the AVS (or AVS 2) style carburetor has adjustable secondary butterfly.

    If you can...increase the initial ignition advance a coupla degrees, see if that helps.
    Another help would be to open the idle mixture screws a little. Go 1/4 turn first, then try 1/2 turn out.
    Another thing...is to put stronger (one step up) springs under the metering rod pistons. They come in the "Jet Kits".

    Mike
     
  7. jaracer
    Joined: Oct 4, 2008
    Posts: 324

    jaracer
    Member

    I may be missing it, but I don't see the secondary air valve in the pictures. It looks like I can see the secondary throttle plates from the top of the carb. The air valve makes the secondaries come on smoothly. If that's missing, it will fall on it's place if you jump on it and probably pop out the carb.
     
    jimmy six likes this.
  8. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,215

    56sedandelivery
    ALLIANCE MEMBER

    Always liked the "AFB" style carbs, no matter who was the owner/manufacturer at the time, and there have been several. The sound of those secondaries opening up always got my attention. Thanks to fastcar1953 up above for posting that Edelbrock link! I knew Edelbrock made a natural finish carb, but they don't seem to be very easy to find; I'm not a "spit and polish" type of guy, especially the Endurashine finish. I am Butch/56sedandelivery.
     
  9. studebaker46
    Joined: Nov 14, 2007
    Posts: 650

    studebaker46
    Member

    search carb king on here great source of info
     
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  10. 67drake
    Joined: Aug 8, 2008
    Posts: 64

    67drake
    ALLIANCE MEMBER
    from Avoca WI

    I’m certainly not a guru,but know a little.
    Many complaints about this carb are exactly what you describe. A lean flat spot when mashing the pedal. Good luck adjusting it out though. You can play with the timing and jetting but you might not get rid of it,and you might be sacrificing in other areas while trying.
    A carb like a Quadrajet has an adjustable air flap over the secondaries to tune the bog out.
    Jon (Carbking) is a wealth of info as mentioned. Talking to him on the phone is a lot easier and productive, if he still takes calls. I don’t know, I haven’t talked to him in a few years!
     
  11. 48fordor
    Joined: Jan 16, 2009
    Posts: 141

    48fordor
    Member
    from York, PA

    I had a 318 Dodge truck with an AFB that did the same thing. Turned out to be a bad fuel pump. Apparently would supply enough fuel for light loads but not for times it needed the accelerator pump shot. I could reproduce it by hitting the throttle multiple times quickly while in park.

    Sent from my SM-G960U using The H.A.M.B. mobile app
     
    loudbang likes this.
  12. Is fuel pressure regulated as recommended by Edelbrock?

    Once again calling @Carbking. Thanks.

    Phil
     
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  13. carbking
    Joined: Dec 20, 2008
    Posts: 2,787

    carbking
    Member

    To all those that mentioned me, I thank you, but do not field questions on the clones. They are on permanent ban from our shop.

    There are others on these forums you should ask.

    Jon.
     
  14. paul philliup
    Joined: Oct 3, 2013
    Posts: 181

    paul philliup
    Member
    from ohio

    I have found that most people don't understand how the metering rods work like a power valve in a Holley.
     
  15. Doug520
    Joined: Apr 21, 2016
    Posts: 25

    Doug520
    Member

    If I understand everyone correctly, my model carb can't regulate how fast or slow the secondaries open. If I can't slow down the secondaries, then the only other adjustment I have available to me is to speed up how fast the fuel gets in to the secondaries once they open quickly. Since there's no accelerator pump on the secondaries, then the only way to do that is to get the secondary fuel rods up into the enriched position as quickly as possible. That would seem to mean new springs on the secondary rod metering system. Does that sound correct in theory? I have checked the idle mixture, checked the timing, all is good there.
     
  16. jimmy six
    Joined: Mar 21, 2006
    Posts: 6,347

    jimmy six
    Member

    The vacuum secondary plate looks missing to me too like jaracer said. Back in the 60’s I could get away with taking them out with std trans but an automatic definitely needed, you could lighten the counter weights a bit but that was always a hit or miss deal.
    Every one I ever saw and the 2 I have in my garage have the upper plate. So did all the Q-jets I ever saw.
     
  17. Doug520
    Joined: Apr 21, 2016
    Posts: 25

    Doug520
    Member

    Thanks Phil - fuel pressure is spot on. Timing got bumped a few degrees advanced and made no difference. Carbking was recommended by multiple folks, but he's made it very clear that he wants nothing to do with this. This Edelbrock is a strange carb design - simple in design yet very complicated because there seems to be little adjustability to it. Very odd.
     
  18. Doug520
    Joined: Apr 21, 2016
    Posts: 25

    Doug520
    Member

    Jimmy, apparently (if I understand this correctly) Edelbrock makes two different series' of carbs - this one that I have, that's designed to have no secondary air doors, and another series (AVS, I believe it's called) that does have the secondary air doors.
     
    jimmy six likes this.
  19. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 2,241

    Lloyd's paint & glass
    ALLIANCE MEMBER

    How about idle? Is it rich? What camshaft is in the motor? Checked vacuum? Float level too low? I've never had that issue and i run these carbs on everything. I know you said you moved the link on the accelerator pump arm, but are the squirters visually working good? Wish i was there in person to help lol
     
  20. fastcar1953
    Joined: Oct 23, 2009
    Posts: 2,126

    fastcar1953
    Member

    I read the the manual and tuned mine. Pretty simple. Bought the tune up kit with rods and springs.
     
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  21. carbking
    Joined: Dec 20, 2008
    Posts: 2,787

    carbking
    Member

    Should you decide to put a genuine Carter AFB that is correct for the application on your engine, I will be very happy to help you determine which Carter to use, and also tech advise. Never any obligation.

    Jon.
     
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  22. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,847

    sunbeam
    Member

    Some one else feels that the Carters are better.
     
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  23. jaracer
    Joined: Oct 4, 2008
    Posts: 324

    jaracer
    Member

    It doesn't matter how fast the secondaries open, you won't get any air flow until the weighted air valve opens. It's the air valve and manifold vacuum that controls air/fuel flow in the secondaries. When you first open the secondary throttle plates, manifold vacuum is low because you also opened the primaries dropping the vacuum. As engine speed begins to climb, manifold vacuum starts to increase which will cause the in-rushing air to open the secondary air valve. No fuel flows in the secondary circuit until you get air flow across the secondary venturi's. It's the air valve that prevents the flat spot and your carb didn't appear to have one.
     
    swade41 likes this.
  24. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,847

    sunbeam
    Member

    Your carb has the air valve you can see it in one picture Very simple setup and foolproof gives less problems than the Holley setup.
     
  25. irishsteve
    Joined: Jan 10, 2017
    Posts: 727

    irishsteve

    Take a look at the accelerator pump shaft.They are made of plastic,and can take a curve over time,and cause problems.If its straight your good.If it has a permanent lean forward I would replace it.
     
  26. 67drake
    Joined: Aug 8, 2008
    Posts: 64

    67drake
    ALLIANCE MEMBER
    from Avoca WI

    Actually the air valve creates low pressure beneath it when the secondaries are opened up. So fuel is drawn out of the orifice before the flap opens. That’s the whole reason for the air valve.
     
  27. saltflats
    Joined: Aug 14, 2007
    Posts: 10,078

    saltflats
    Member
    from Missouri

    Have you looked at the spray from the accelerator pump nozzles?
     
  28. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,539

    dirty old man
    ALLIANCE MEMBER

    We have a couple of people posting about a secondary air valve being in this carb. There is no secondary air valve in this particular carb, weighted or otherwise. The plate one poster thinks is an air valve on the secondary is a choke plate on the primary side, for God's sake!!!!!!
    Careful tuning will get most of the hesitation out, but in real life, the only way to get this carb to work right on this engine is to EDUCATE YOUR RIGHT FOOT!!!!!!!!
     
    Last edited: Apr 6, 2020
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  29. old.hot.rodder
    Joined: Oct 13, 2012
    Posts: 160

    old.hot.rodder
    Member

    Here is my 2 cents. I have played a lot with these. What I have found (as strange as it seems) is too much fuel from the accelerator pump for the engine to handle it under the mash it condition. I would try disconnecting the accel pump and try it. I know it sounds stupid but it might tell you something without much work. Then you have a direction as to what discharge nozzles to use.
     
    loudbang likes this.
  30. Now these are Carters, but if you watch the video you'll see me (the linkage) opening the carbs, listen to the rpms as it rolls that air in and starts opening the secondaries. You can hear the engine responding by the rpms climbing and it taking in the fuel, these are a pair of Competition series 600's with 1-1 linkage.
    I've never seen one of these style carbs without the back air door, kinda weird.

     
    loudbang likes this.

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