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Hot Rods H.A.M.B. brains needed

Discussion in 'The Hokey Ass Message Board' started by classicdreamer, Jan 29, 2019.

  1. classicdreamer
    Joined: Nov 5, 2009
    Posts: 592

    classicdreamer
    Member
    from nyc
    1. A-D Truckers

    for the past year or so my 38 ford has been choking on wide open throttle. It has a crate 350 sbc, unsure of the specs. Has a turbo 350 in it. It Falls on its face. Let off and it regathers itself. Pulls hard with a normal foot. PUZZLED!!!!
    Things done so far:
    Put in new mechanical fuel pump. Pump was reading before 2-6 lbs. new one at 6lbs.
    Replaced old accel dist with a summit ready to run and then to a msd ready to run. All vac advance.
    Replaced spark plug wires.
    Replaced spark plugs
    Replaced 1406 edelbrock carb with avs 650 edelbrock. Vacuum at 16lbs.
    Added inline fuel filter
    Blew out fuel line
    Checked inside tank and it’s clean, almost new.

    After replacing the carb, it performs drastically better that it did before with the old carb.

    Missing something....... please share thoughts.
     
    chryslerfan55 likes this.
  2. classicdreamer
    Joined: Nov 5, 2009
    Posts: 592

    classicdreamer
    Member
    from nyc
    1. A-D Truckers

    Also swapped out carb to a running Holley650 and it does the same shit.

    Found an unknown fuel filter on top of the tank that was clogged to shit and it Did the same.

    The fuel line is 3/8” hardline from front to back
     
    chryslerfan55 likes this.
  3. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 1,014

    TrailerTrashToo
    ALLIANCE MEMBER

    Trash in the line between the fuel pump and the carb?

    In 1965, as a college dropout, I was pumping gas at the corner gas station (The "traditional" occupation for a college dropout). Our 1956 F-series pickup gave the same symptoms going up the big hill out side of town. We found a small chunk of fuel line rubber in the fuel line. It would settle to the bottom (fuel pump end). High flow rates would push the trash against the carb inlet.
     
    OahuEli and chryslerfan55 like this.
  4. If the pick-up in the tank has a "sock" strainer on it, it is likely clogged. It does sound like a fuel delivery problem. The tubing from tank to pump could also be clogged or pinched at some point.
     
    OahuEli, 1946caddy and chryslerfan55 like this.

  5. oj
    Joined: Jul 27, 2008
    Posts: 6,257

    oj
    Member

    Can you describe what you mean by 'choking at WOT'? Is it as if you are driving along and slam the throttle only to have it fall on its face? If yes, does it start to pull? When this 'choking' is there any smoke out the tailpipe, backfire thru exhaust or carb? Is it strong otherwise, pulls hard thru the gears etc? Is it just goofy at WOT?
     
    King ford likes this.
  6. classicdreamer
    Joined: Nov 5, 2009
    Posts: 592

    classicdreamer
    Member
    from nyc
    1. A-D Truckers

    Oj, if I am driving normal and then floor it at any speed it cuts out and falls on its face. Let off the gas and it recovers. Drives great normal up until you nail it
     
    chryslerfan55 likes this.
  7. Nova Thug
    Joined: Jun 9, 2012
    Posts: 180

    Nova Thug
    Member
    from SG Vizzle

    Is your distributor clamp holding the distributor securely..? (Not trying to be funny here but a friend was having a problem with his car not reacting as he thought it should and it turned out the the distributor clamp was not doing it’s job..)
    What kind of rpm’s does the problem occur?
    Does it behave badly if you slowly build up to WOT vs mashing the go peddle from a standstill?
    Have you checked your floats?
    What diameter fuel line are you running?
    How is the fuel pickup situated in the tank..?
     
    King ford and chryslerfan55 like this.
  8. rjones35
    Joined: May 12, 2008
    Posts: 865

    rjones35
    Member

    It does sound like a carb tuning thing, if it'll recover if you let off a little, then keep going if you ease into it. Maybe squirters too big or small, too much accelerator pump shot, not enough, something along those lines.
     
    big duece likes this.
  9. oj
    Joined: Jul 27, 2008
    Posts: 6,257

    oj
    Member

    And, it does the same thing with more than 1 carb? The Edelbrock AVS being the better of the three? And if you come down on the throttle casual it'll pull hard? Its just when you throw your foot into it? When you thro your foot into it does it stumble and then goes? or do you have to back off on the throttle for it to recover?
    Sorry about so many questions.
     
    chryslerfan55 likes this.
  10. If this is a Carter AVS carb, that means it has an Air Valve Secondary. Which is a good thing because it's quite easily adjustable. The secondary air valve is spring loaded, like on a Q-Jet, and just a easy to tune. The Carter AFB's use a counter-weighted secondary air valve, which usually works OK, but isn't quite as flexible.

    My guess is that the secondary air valve on the AVS is too loose and is opening too quickly. Look online for the procedure if you haven't done it before, like maybe on a Q-Jet, and try tightening up the tension spring a turn or half turn at a time and see if the bog improves. It's not "choking", it's actually going lean when the secondaries are cracked open because the air valve is opening too soon, before it can start pulling fuel thru the secondary main nozzles.

    As a rule, lighter cars with manual trans, or automatics with a loose converter and lower gears like a looser air valve adjustment. Heavier cars with a stock stall converter and higher axle ratios like a tighter air valve adjustment.
     
    chryslerfan55 and alanp561 like this.
  11. Bigchuck
    Joined: Oct 23, 2007
    Posts: 1,145

    Bigchuck
    Member
    from Austin, TX

    Stick the fuel line from the pump to the tank in a gas can to bypass the fuel line and tank in car. See what happens.
    A few years back I was going nuts trying to make a small block Chevy run right for a guy. It was in an off topic project car that somebody else had rebuilt the engine in. How hard can that be, right? Well the answer is a pain in the ass!,
    I tried different known good carbs, distributors checked and rechecked everything till I was about to go nuts. I finally told the guy I was going to have check the chain timing and Bingo! Whoever put the engine together had it way off. Not sure how it ran at all but, after fixing that all was good.
     
    chryslerfan55 likes this.
  12. Rah Rah Records
    Joined: Aug 16, 2011
    Posts: 80

    Rah Rah Records
    Member

    Sounds like vacuum problem to me. I'd check the vac hoses for leaks and make sure they're attached to the correct ports. My slant six did the same when I got it. PO had the vac advance running off the manifold port.
     
    clem, slack and FlyingRN like this.
  13. GordonC
    Joined: Mar 6, 2006
    Posts: 2,412

    GordonC
    ALLIANCE MEMBER

    Had a buddy who had the same problem in his 64 galaxy convertible. He was running the car with no air cleaner on it and every time he put his foot in it it sucked the under hood liner down onto the carb and it had the same symptoms as yours. If he pedaled it normally no problem. I saw it and told him to put an cleaner on it or get rid of the under hood liner. He put an air cleaner on it and it ran fine. Just saying...
     
    chryslerfan55 likes this.
  14. Flathead Dave
    Joined: Mar 21, 2014
    Posts: 3,400

    Flathead Dave
    ALLIANCE MEMBER
    from So. Cal.

    I see the problem. Swap your 350 out for FORD power.
     
  15. F&J
    Joined: Apr 5, 2007
    Posts: 13,223

    F&J
    Member

    If it was me after all that frustration, I'd hook the vac advance to a full manifold vac source, instead of ported source, and then set timing on the road by trial & error. Worth a try, as it's easy and zero$ costs to perhaps help diagnose it over the web.
     
  16. Baumi
    Joined: Jan 28, 2003
    Posts: 2,765

    Baumi
    ALLIANCE MEMBER

    I had the very same issue with my 355 SBC in a 34 Plymouth. I was running out of fuel and falling on it´s face over 4500 rpm. I also had a 3/8" line, but 2 elbow brass fittings were too small inside. Like 1/4" or so. I just drilled them to 8mm and the problem went away. It was hard to identify. Flooring it in 1st and 2nd was fine, but in 3rd at 4500 it just starved.... hope that helps!
     
    lothiandon1940 likes this.
  17. F&J
    Joined: Apr 5, 2007
    Posts: 13,223

    F&J
    Member

    well....he did say that it falls flat on a WOT instantly...so that eliminates a fuel delivery issue up to the carb itself.

    The fuel bowl cannot instantly get low if he hits it hard after just driving normal, right?

    Meaning that if it only bogged after he ran it fairly hard up a long hill, then jumped on it ..then yes it could be a delivery-to-carb issue.
    .
     
  18. classicdreamer
    Joined: Nov 5, 2009
    Posts: 592

    classicdreamer
    Member
    from nyc
    1. A-D Truckers

    I hear you on swapping to a ford, would like to put a raptor motor in it.

    I am about to pull the line from the tank and put it in a hand held gas tank.

    The car runs the same with it without a air cleaner.
     
  19. classicdreamer
    Joined: Nov 5, 2009
    Posts: 592

    classicdreamer
    Member
    from nyc
    1. A-D Truckers

    OJ, And, it does the same thing with more than 1 carb? Same issue 3 carbs, 2 edelbrock and 1 Holley

    The Edelbrock AVS being the better of the three? Avs feels better that the other 3

    And if you come down on the throttle casual it'll pull hard? Yes pulls strong casually driver.

    Its just when you throw your foot into it? It only falls on its face at WOT

    When you thro your foot into it does it stumble and then goes? or do you have to back off on the throttle for it to recover? I have to lift off the. Gas in order for it to recover. If I nail it again, same thing chokes.
     
  20. squirrel
    Joined: Sep 23, 2004
    Posts: 49,326

    squirrel
    Member

    Tell us about how you set the ignition timing

    Sent from my Trimline
     
    BradinNC likes this.
  21. Baumi
    Joined: Jan 28, 2003
    Posts: 2,765

    Baumi
    ALLIANCE MEMBER

    Maybe, maybe not. haha!

    Go Ford, if you want more problems that are even more expensive to fix, hahaaaha
     
  22. oj
    Joined: Jul 27, 2008
    Posts: 6,257

    oj
    Member

    How does the motor itself 'feel', does it feel weak when you mess with the throttle by hand? Like it should have more power than it has?
     
  23. bdynpnt
    Joined: Feb 9, 2009
    Posts: 354

    bdynpnt
    Member

    Could be weak spark too under load compression can blow out the spark if it's weak

    Sent from my SM-G965U using The H.A.M.B. mobile app
     
  24. classicdreamer
    Joined: Nov 5, 2009
    Posts: 592

    classicdreamer
    Member
    from nyc
    1. A-D Truckers

    The motor feels stronger than it ever did in the 2 years I have owned it.
    I bought the car as a 4spd and converted it to auto. I don’t remember it falling on its face when the 4spd was in it.
     
  25. bdynpnt
    Joined: Feb 9, 2009
    Posts: 354

    bdynpnt
    Member

    Check your spark, when plugs and or wires start to go they miss on acceleration could be a weak coil or other ignition items

    Sent from my SM-G965U using The H.A.M.B. mobile app
     
  26. classicdreamer
    Joined: Nov 5, 2009
    Posts: 592

    classicdreamer
    Member
    from nyc
    1. A-D Truckers

     
  27. bdynpnt
    Joined: Feb 9, 2009
    Posts: 354

    bdynpnt
    Member

  28. oj
    Joined: Jul 27, 2008
    Posts: 6,257

    oj
    Member

    Cast iron head? and the spark plug is a ?
     
  29. Bill Rinaldi
    Joined: Mar 23, 2006
    Posts: 1,843

    Bill Rinaldi
    ALLIANCE MEMBER

    What happens if you manually down shift when you go WOT? Any chance your down shift is not catching up to your throttle foot? Bill
     
    clem likes this.
  30. 3340
    Joined: Jun 4, 2010
    Posts: 577

    3340
    Member

    Try with the fuel cap loose or off, sounds fuel related


    Sent from my iPhone using H.A.M.B.
     
    lumpy 63 and King ford like this.

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