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Customs Holley Carb issues!

Discussion in 'The Hokey Ass Message Board' started by Karl M, Aug 20, 2019.

  1. Karl M
    Joined: Jul 19, 2017
    Posts: 119

    Karl M

    Holley 4160 problems!
    Bought vehicle, 350 small block, Holley 4160.
    Replaced primary pump and other parts in the primary fuel bowl to get vehicle running.
    Ran ok than developed a whistling vacuum leak.
    Pulled carb replaced gaskets and rebuilt back fuel bowl.
    Put it all back together, ran ok for ten miles, now it will not idle when putting it into gear, drive or reverse.
    Adjust float level up and down, no good.
    Adjusted air mix needles, no good.
    Adjusted idle screw, no help.
    Adjusted timing no help.
    Shot cab cleaner through the needle screw ports and compressed air, no help.
    fuel filters clean
    exhaust smells rich, some black smoke when reved up
    Adjusted pump level screw, no help
    When taking fuel bowl sight plug out to check float level in the primary bowl the idle would normalize...sucking air in...?

    Next recourse pull primary fuel bowl , check it out, replace the power valve assembly, possible bad fuel pump?
    Has new plugs, wires, HEI
    Rig is a 57 Willys wagon
    Thanks for any ideas.
    Carl
     
  2. Plugged vent tube.
     
    Boryca, blowby and Deuces like this.
  3. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 7,802

    Bandit Billy
    ALLIANCE MEMBER

    Did you use thread sealer when you put the carb back on? Hey, I've done it, messed up a couple carbs learning not to use it again. It will cause Johnny's scenario above.
     
  4. LM14
    Joined: Dec 18, 2009
    Posts: 1,937

    LM14
    Member Emeritus
    from Iowa

    Shoot carb cleaner thru the air bleeds and vent tube. Be sure the air cleaner lid isn’t sucking down too love to the vent tube.
    SPark
     
    Oldioron and Black_Sheep like this.

  5. Sometimes running rich will be caused by a pooched power valve. Another possible issue, is that sometimes the faces of the blocks can be warped, and when you assemble the carb with new gaskets, the carb will not be properly sealed.
    Bob
     
  6. Karl M
    Joined: Jul 19, 2017
    Posts: 119

    Karl M

    No thread sealer.
     
  7. Karl M
    Joined: Jul 19, 2017
    Posts: 119

    Karl M

    I ran it with and without the air cleaner, same result, but will check out the vent tube.
     
  8. Karl M
    Joined: Jul 19, 2017
    Posts: 119

    Karl M

    I will pull the primary bowl and replace the power valve, did not do this yet.
     
  9. My Holley did the same thing , it was the power valve !
     
  10. 26Troadster
    Joined: Nov 20, 2010
    Posts: 628

    26Troadster
    Member
    from Texas

    power valve was my first thought.
     
  11. Karl M
    Joined: Jul 19, 2017
    Posts: 119

    Karl M

    Hoping it is the power valve...has ran a little rich from day one. Maybe when I fixed the vacuum leaks on the carb, the poor power valve overwhelmed everything ...
     
  12. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,027

    Boneyard51
    Member

    Did it backfire at any time? That will do the power valve in! Newer carbs have a “ power valve saver valve” in them to help prevent this. Big problem on older carbs.




    Bones
     
  13. Karl M
    Joined: Jul 19, 2017
    Posts: 119

    Karl M

    Yes it did back fire a few times!
     
  14. Spot fixing carburetors is like a NASCAR driver saying he has a left side flat and they only replace the left side tires on a pit stop and then he has to come back in to replace the right side tires that were flat in the first place.
    On a Holley the first place to look for a problem is the power valve; is it the right one for the tune, is it blown, is it the right one for the carburetor.
     
  15. Don't forget while you have the carb apart. Put a straight edge diagonally across the carb faces and the plates to check for distortion. If previous owners have over torqued the screws that are used to attach the metering plates and the bowls, the carb faces will probably be warped and require gentle filing to true them up again.
    Bob
     
  16. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,027

    Boneyard51
    Member

    Your power valve is probably junk, especially if it’s an older carb. I think they started putting the saver valves in about twenty years ago. If yours does not have one, they make a kit to put one in for about $12. Did quite a few back in the day. For me is was just part off a rebuild.




    Bones
     
    Truckdoctor Andy likes this.
  17. If it is the power valve it must be loose then. Blown power valves diaphragm alone will not make a carb go rich, the opposite. Now if it's loose it will allow vacuum to pull fuel from bowl and create vacuum within in the bowl (per OP's words) providing vent tube is plugged.
    [​IMG]
     
    Deuces likes this.
  18. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,394

    2OLD2FAST
    Member
    from illinois

    Huh ??? The only thing between manifold vacuum and the float bowl is the diaphragm , with a blown diaphragm , fuel is sucked directly into the manifold ......
     
  19. Truck64
    Joined: Oct 18, 2015
    Posts: 4,759

    Truck64
    Member
    from Ioway

    PV protection since 1992, an easy check for a blown valve is lean out the idle mixture screws, if the engine stumbles/ stalls, the power valve is not blown. It does happen but it's one of those stories that gets told and retold over the internet and takes on a life of its own.

    Somebody at Fordbarn tested some with a Mityvac and found they can be sometimes be way off their listed opening point. Probably worth checking before installing.
     
    Deuces and Boneyard51 like this.
  20. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,027

    Boneyard51
    Member

    Power valves in the older carbs blew quite often. Holley invented Power valve saver valves and included them in the later carbs to cure this problem. If it wasn’t a problem, they wouldn’t have taken the time and money to do this.
    If your power valve ruptures the diaphragm, you will go very rich as the fuel will flow through the diaphragm directly into the intake manifold.
    It depended on the driver as to how often it blew, backfires were/are the main cause of failed power valves.




    Bones
     
    Last edited: Aug 21, 2019
  21. Truck64
    Joined: Oct 18, 2015
    Posts: 4,759

    Truck64
    Member
    from Ioway

    Backfire? Or backfire through the carb? Both?? It was more of a perfomance application problem? I've never had a bad power valve just zookin' around. I'm glad I never paid attention to any of this stuff years ago, I wouldn't left the garage. Points, generators, drum brakes, and now carbs.
     
    Boneyard51 likes this.
  22. Deuces
    Joined: Nov 3, 2009
    Posts: 20,564

    Deuces
    Member
    from Michigan

    Looks like an L-88 carb....^^^^^...;)
     
  23. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,027

    Boneyard51
    Member

    Truck64, it was a trip, back then. I usually drive my modern cars around, but I get reminded of the old days, every time I take one of my 65 Fords out for a cruise. Start it up, jiggle the throttle a little till it warms up a little, put it in gear, wiggle the foot feed, to richen the mixture a little, very lightly, to avoid coffing/ backfire through the carb. Down the road a spell you are ready to go. You kinda had to “ learn” a car.
    The power valve problem was equally spread between OEM and performance carbs.... as they were very similar.
    The diaphragm power valve was what made Holley famous..... and also cussed!
    It was a different world back then. Better power valves and power valve saver valves have brought the Holley back.



    Bones
     
    Truck64 likes this.
  24. Karl M
    Joined: Jul 19, 2017
    Posts: 119

    Karl M

    Great info. Looks like it was the power valve! Idles nice and runs smooth. It is still a bit rich though. Float level seems good, air mix needles are just one and an eighth to one and a quarter turn out. Will check a few plugs tomorrow. The power valve is 7.5, that is what came with the kit. Could not make out what the old one was. To much fun ;-)
     
    David Gersic likes this.
  25. At idle? I'm sure Karl didn't pull bowl plug while car was under a load.
    [​IMG]
     
  26. jimcolwell
    Joined: Oct 4, 2009
    Posts: 474

    jimcolwell
    Member
    from Amarillo

  27. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,394

    2OLD2FAST
    Member
    from illinois

    The vac port in the carb base is always exposed to manifold vacuum .that's what holds the PV closed , when the vacuum falls below the PV spring tension , it opens the PV. If the PV diaphragm is ruptured , fuel will be drawn through the PV because vac won't hold a ruptured diaphragm closed ...
     
    Last edited: Aug 21, 2019
  28. Yes it is. I wanna know how fuel bowl can create vacuum as if it were a closed container?
     
  29. Boneyard51
    Joined: Dec 10, 2017
    Posts: 5,027

    Boneyard51
    Member

    Johnny Gee, take a Holley carb, leave the power valve out( blown power valve ),and try to fill the front fuel bowel. You can’t do it!




    Bones
     
    egads likes this.
  30. Truck64
    Joined: Oct 18, 2015
    Posts: 4,759

    Truck64
    Member
    from Ioway

    This guy claims (I think) a ruptured power valve can't affect idle mixture. Even if true, it would definitely bugger the fuel mix at cruise. For the same reason it is very important to select the proper PV that does not provide any enrichment at cruise, especially when deciding on jetting calibration.

     

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