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Technical Quadrajet Woes

Discussion in 'Traditional Customs' started by Slimchanse, Oct 11, 2021.

  1. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    Hi all-
    It's been a while since I've posted, but always finding good bits of info on here. Hopefully I'm posting in the right section...having fuel system issues with my 52 and have isolated it to my carb. There's a new tank, sending unit, lines are good, fuel pump is good, but I can't keep it running/idiling. After rebuilding the carb to the best of my ability, fuel is coming from a hole between the primary's venturis/tubes (pic included) on acceleration/when the throttle linkage is actuated. Is the float level off and creating a flooded situation? Bad gasket? Am i missing a check (ball) valve? (Idk, am I? Some self-depracating humor to combat the frustration)...I apologize for any inaccuracies in explaining parts and the symptoms, but I've rebuilt the carb years ago and have never seen fuel 'weep' out of that center hole and am thinking that has something to do with it not running, or more specifically even staying running/idiling. I attached a few pics and thank you in advance for considering helping me. The carbs been off and on now 4 or more times, but I'm just stubborn enough to not take it to someone.
     

    Attached Files:

  2. saltflats
    Joined: Aug 14, 2007
    Posts: 10,929

    saltflats
    Member
    from Missouri

    Check float level.
    That's not a quadrajet.
     
    loudbang likes this.
  3. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    Saltflats-
    Thank you for the quick reply and checking me on that...Rochester 4 Jet RP then? So if the float level is off (not low enough it will create a flooded state, the car won't run and excess fuel may come out that center hole in the primary cluster assembly?
     
  4. anthony myrick
    Joined: Sep 4, 2009
    Posts: 8,656

    anthony myrick
    Member

    Nice ride
    Need a better pic of the carb
    most leaks above that area are float or high fuel pump pressure issues.
     
    dana barlow likes this.

  5. anthony myrick
    Joined: Sep 4, 2009
    Posts: 8,656

    anthony myrick
    Member

    If that’s a 4 jet, they are pretty straight forward. The floats are easy to get off.
     
    Last edited: Oct 11, 2021
  6. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    Anthony-
    Thank you. Nice hat :) Ok, the mechanical fuel pump is working/pumping fuel up to the carb, but I have not tested the pressure. I am leaning towards an issue with the floats.
     
  7. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    Yes they are...I can't seem to get it right...I do have a service manual.
     
  8. anthony myrick
    Joined: Sep 4, 2009
    Posts: 8,656

    anthony myrick
    Member

    Check the floats. Make sure the BB is in the correct hole.
    After that ya might want to check fuel pressure.
     
    Deuces likes this.
  9. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    BB? check (ball) valve? There's one in the acc. pump and one in or under the primary (I think it's kept in place by a little metal rod)?
     
  10. Mr48chev
    Joined: Dec 28, 2007
    Posts: 30,030

    Mr48chev
    ALLIANCE MEMBER

    Correct info as to exactly what carb it is gets better info from the people who know that particular carb. Just calling it a Qjet because it is a Rochester 4 barrel doesn't fly because we are picking our brains for Qjet info and probably searching for an idle circuit diagram online.

    Gas running out the main discharge nozzles at an idle most likely as they said, mean that either your float level is off or your floats aren't floating. Or possibly your fuel pressure is way too high.
     
  11. squirrel
    Joined: Sep 23, 2004
    Posts: 49,812

    squirrel
    Member

    What carb is that? not a Rochester 4jet, it doesn't have the vent tubes

    We need good pictures...show the whole carb....but it looks like it might be the Autolite 4300 series carb, Ford's version of the Qjet. Which was a really crappy carb, although some folks can get them to work right.

    But again, pictures...
     
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  12. anthony myrick
    Joined: Sep 4, 2009
    Posts: 8,656

    anthony myrick
    Member

    Need a better pic
     
  13. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    Ok, thank you for the responses I will get some better pics after work.
     
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  14. 325w
    Joined: Feb 18, 2008
    Posts: 5,648

    325w
    ALLIANCE MEMBER

    Did you buy a Q jet kit to do the rebuild?
     
    Mark Yac likes this.
  15. anthony myrick
    Joined: Sep 4, 2009
    Posts: 8,656

    anthony myrick
    Member

    Also make sure the floats actually float.
    We had a similar issue with a Stromberg.
    Had to re-solder the float
     
    Deuces likes this.
  16. I think you're right, Jim. Not something you want to tinker with..Late 70's are very lean, and I don't think you can get bigger jets for them.
     
  17. Joe Travers
    Joined: Mar 21, 2021
    Posts: 421

    Joe Travers
    Member
    from Louisiana

    The late '60s-early '70s 4300s were installed on some beefy engines and are the ones to look for, particularly for 351C, 429 or 460 engines. Not as good as the older 4100, IMO.

    Joe
     
  18. I don't know..I can't nail it down..None of the 4300 series seem to have a bolt in venturi cluster. That looks more like RP... I'll wait for the pics ;-)
     
    squirrel likes this.
  19. nosford
    Joined: Feb 7, 2011
    Posts: 550

    nosford
    Member

    Okay, the hole you are talking about that fuel comes out of is the hole in the brass plug next to the silver screw? It only happens when you move the throttle? It looks like that plug/hole is part of the accelerator pump nozzle and it looks like there would be a check ball underneath so it would plug that hole so fuel would only come out the nozzles but allow air into the circuit when the accelerator pump was not creating pressure. The float level would not have anything to do with that circuit and shouldn't affect idle but would cause a stumble or hesitation upon throttle opening. I think you have two different problems. Just a guess!
     
  20. Still need carb identification photos.

    @carbking might be able to help, depending on which carb you have.
     
  21. carbking
    Joined: Dec 20, 2008
    Posts: 3,159

    carbking
    Member

    Picture requires a crystal ball, and mine is broken. :p

    Picture resembles an early Rochester 4GC. Some of them had a check valve in this area. Oldsmobile if my memory is not faulty. If the check valve is stuck, it might be possible for fuel to leak out the vent hole.

    Jon.
     
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  22. carbking
    Joined: Dec 20, 2008
    Posts: 3,159

    carbking
    Member

    Sematics:

    Both the early Rochester square-bore 4-barrel currently known as the 4G series, and the newer 4M and 4MV spread-bore 4-barrels were called "quadrajet" by Rochester.

    Most enthusiasts refer to ONLY the spread-bore as a quadrajet, but the term quadrajet is correct for both.

    To eliminate or at least minimize confusion, using the terms 4G, 4M, or 4MV is helpful.

    Blame Rochester! :p

    Jon.
     
  23. squirrel
    Joined: Sep 23, 2004
    Posts: 49,812

    squirrel
    Member

    Ah, now I see the single bowl vent tube just to the left of the finger/thumb...
     
  24. I think the early Cad models had the single vent.
    Yes, if the gas is coming out the hole in the center of the squirter, there most likely a check ball missing. Later models didn't have that deal. Still need more info.
     
  25. carbking
    Joined: Dec 20, 2008
    Posts: 3,159

    carbking
    Member

    Mark - you may be correct on it being Cadillac, I remembered Olds, but memory sometimes gets me in trouble. :( I know it did NOT work well, and only lasted a couple of years.

    The early WCFB Carters were superior to the early 4G Rochesters. By about 1955, the Rochesters were much improved.

    Jon.
     
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  26. jimmy six
    Joined: Mar 21, 2006
    Posts: 9,988

    jimmy six
    ALLIANCE MEMBER

    Jon. It’s funny you should say that. I use early WCFB’s and heard in 53 the warrantee replacement for a WCFB on a Cadillac was a Rochester 4GC. I have a perfect restored one that’s been done by a high dollar restoration shop that I cannot get to run. I replaced it with a Carter..
     
  27. carbking
    Joined: Dec 20, 2008
    Posts: 3,159

    carbking
    Member

    GM owned Rochester; they did not own Carter. Money talks!

    ANY carburetor work done in the Chevrolet dealerships in the early 1950's, unless the customer specified otherwise; replaced the vastly superior Carter W-1 from 1932~1949 with the vastly inferior Rochester B.

    Again, money talks!

    Jon
     
  28. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    Man, thank you guys for all the replies! Yes, it's a Rochester 4Jet RP. Ok, I was thinking I'll have to take the carb apart and look at the floats, but then I saw one of the idle screws (pic attached) the tip broke off. Could that missing screw tip be the sole cause of it not being able to maintain running/idling?
     

    Attached Files:

  29. anthony myrick
    Joined: Sep 4, 2009
    Posts: 8,656

    anthony myrick
    Member

    that will affect the its idling if not set properly or not able to be set properly
     
  30. Slimchanse
    Joined: Jan 26, 2012
    Posts: 22

    Slimchanse
    Member
    from Crosby, TX

    No, I didn't buy a rebuild kit....just cleaned everything with brake cleaner and reassembled. I did notice one of the floats counter-balance springs was wore out, but I thought I got the float levels right and them functioning (tipping the top of the carb upside down and right side up) the floats moved well, held position and the needle wasn't sticking anymore.
     
    Last edited: Oct 12, 2021

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