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302 pain in my a$$

Discussion in 'The Hokey Ass Message Board' started by mr. h, Aug 11, 2013.

  1. i have a 53 ford customline with a 72 block 302 bored .60 over with 351 heads, air gap intake, 1405 carb. it has a mild cam as well. so a few weeks ago it started running rough and only running when choked down, (manual choke). i found that my intake valley gasket had pushed out. i got the good intake gaskets and re built everything. im positive i have a good seal on the carb and intake. i have tested all vacuums and they are good and sealed. i have a clean gas tank and fuel filter. here is what it does. it starts fine under choke and the revs up high. it will surge up and down a bit and when i un choke it even slightly it bogs down and dies. i have to keep pumping the gas to get it to run when its not choked down and when driving it surges up and down like revs up and down on its own. i cant find any vacuum leaks anywhere and ive pressure tested the intake and its sealed up good. any ideas what in the world is going on? the carb is pretty new and only has 1000 or so miles on it. im at a loss on whats going on
     
  2. kidzintha34fodor
    Joined: Feb 12, 2009
    Posts: 408

    kidzintha34fodor
    Member

    are you running non-ethonal gas? have you checked your float bowl for debrit? did you use the ARP step bolts when you put the 351W heads on?
     
  3. Sounds like a carburetor problem. HRP
     
  4. im running ohio gas, not sure of the ethanol content. ive cleaned the carb out several times. and yes the correct head bolts are in and torqued good. I did blow the head gaskets about 4 months after I got it running cause I was not moving enough water. now I have a high flow pump and 32 inch wide radiator and it runs at 180 degrees all day every day. I have been using some octane booster as well.
     

  5. OldColt
    Joined: Apr 7, 2013
    Posts: 504

    OldColt
    Member

    Sounds like a big vacuum leak, but you say you have fixed the intake valley gasket, and the vacuum checks ok.

    If you have to pump the gas to keep it running, it sounds to me the main fuel circuit in the carb is not working, and it is relying on the accelerator pump's fuel squirts to keep running.

    --- Steve ---
     
  6. I only have to pump it when the choke is open all the way.
     
  7. Dirt in the idle circuit.
     
  8. My friend had a similar problem. It could be the Carb.We were ruling out that the carb was the issue because it was fairly new. We removed the top off of the Edelbrock and we found some debris in the fuel passage ways.
     
  9. OldColt
    Joined: Apr 7, 2013
    Posts: 504

    OldColt
    Member

    That would make sense, because the mixture would be that much leaner with the choke open. Obviously there is not enough fuel for the amount of air ingested, because it is relying on the accelerator pump. More fuel needs to be getting through the jets to mix with the incoming air. I'd check for adequate fuel getting to the carb (like cranking over with the fuel line in a mason jar). If that's ok ...some fuel passage is probably clogged up, or the power valve or enchrichment circuit may have stopped working. Hope that helps.

    --- Steve ---
     
  10. saltflats
    Joined: Aug 14, 2007
    Posts: 10,841

    saltflats
    Member
    from Missouri

    I am with these guys check the carb.
     
  11. I'm running an edelbrock 1405. Anyone suggest something better?


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  12. what is the fuel pressure reading when the car is idling? how about when it starts surging?

    have you tried a new pump? didnt see that mentioned above
    just a thought
     
  13. this, just dont clean the carb bowl out, clean jets and passages, new carb or not.
    It does matter.
     
  14. I'm running an electric fuel pump and my pressure stays the same, sits right at 4 3/4


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  15. saltflats
    Joined: Aug 14, 2007
    Posts: 10,841

    saltflats
    Member
    from Missouri

    I am a holley guy but I am sure that your carb will be fine.
    Just take the top off and see what it looks like be carful bring the gasket up with the top and maybe you wont need a kit.
     
  16. I bought a rebuild kit but I've never rebuilt one before


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  17. 4 3/4 sounds kinda low to me. Should be 6-8
     
  18. George
    Joined: Jan 1, 2005
    Posts: 7,438

    George
    Member

    The valley end gaskets aren't involved with engine vaacum, but if you don't have the PCV system set up right crankcase pressure could push them out, unless they wern't glued down good & pushed out when you torqued the intake down. Still wouldn't afect vaacum.
     
  19. I have the Pcv going to the back of the carb. Is that right?


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  20. i would be more concerned on low fuel pressure
     
    Last edited: Aug 11, 2013
  21. Deuces
    Joined: Nov 3, 2009
    Posts: 20,552

    Deuces
    Member
    from Michigan

    Thought you never ask...:D:D:D
    Ditch the brock and get a real carb for it...
    A Holley 600 w/vacuum secondaries List# 1850...;)
     
  22. buddy had same problem with new 1405 carb. Couldn't be fixed had to buy new carb.
     
  23. fridaynitedrags
    Joined: Apr 17, 2009
    Posts: 402

    fridaynitedrags
    Member

  24. George
    Joined: Jan 1, 2005
    Posts: 7,438

    George
    Member

    No, I believe it's supposed to go to the front between the adjustment screws, have mine set up this way. The one in back is for something else & I have it plugged on mine. Do you have an inlet for the air to get in?
     
  25. saltflats
    Joined: Aug 14, 2007
    Posts: 10,841

    saltflats
    Member
    from Missouri

    ^^ there you go ^^ how to rebuild
    I don't think it would have a idle problem with 4.5 fuel pressure it may run out at top end .
     
  26. fridaynitedrags
    Joined: Apr 17, 2009
    Posts: 402

    fridaynitedrags
    Member

    This is a common mistake, setting the pressure too high and allowing the pressure to overcome the needle and seat. When that happens, the pump blows raw fuel into the intake manifold and you will have a tuning nightmare that won't go away until you lower the pressure. I know you've heard guys complain about smelling gas and observing black smoke from the pipes.....this is the problem they're having......too high fuel pressure.

    NOW HEAR THIS......
    Carburetors are not like EFI. More pressure will not make more power. All it will do is generate a tuning nightmare for you. Edelbrock, Rochester and Carter likes 4 1/2 -4 3/4 psi. Holley will tolerate 5 1/2 -5 3/4.
     
    Last edited: Aug 11, 2013
  27. fridaynitedrags
    Joined: Apr 17, 2009
    Posts: 402

    fridaynitedrags
    Member

    Another common misconception. Pressure is not what keeps the motor fed, VOLUME is what keeps the motor fed. Use large supply lines (1/2" minimum for a street motor) and a reasonable fuel pressure, based on what I said in post 26.
     
    Last edited: Aug 11, 2013
  28. fridaynitedrags
    Joined: Apr 17, 2009
    Posts: 402

    fridaynitedrags
    Member

    Well, I guess a guy is either smarter than the carburetor.....or he's not. :eek:
     
  29. 40FordGuy
    Joined: Mar 24, 2008
    Posts: 2,907

    40FordGuy
    Member

    About parts; "New only means Shiny" ! I'd guess we've all found that out the hard way.......

    4TTRUK
     
  30. SMOG_GUY
    Joined: Jun 28, 2011
    Posts: 388

    SMOG_GUY
    Member
    from Dinuba

    Dirty carb makes it idle high and dumb?
    MUCH more likely you have a hidden vacuum leak, no matter what you say.
    You need a smoke machine. It pushes non-toxic smoke down a hose that you can connect to carb or intake manifold.
    I understand that not everyone has one.
    Everyone here would say use aerosol carb cleaner to find the leak. I've started fires that way.
    Little hobby propane tank with smallest torch tip crack valve unlit and wave torch end all over top of engine while it runs.
    Or a squirt gun with water in it.
    Disable PCV and try again.
    Engine should not react to propane unless it has a leak. Keep torch from directly putting propane into carb opening.
    Really sounds like a big air leak.
     

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