Holley Carb Blues

Discussion in 'Gas Engines' started by TollyWally, Jun 8, 2009.

  1. TollyWally
    Joined: Mar 2005
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    Location: Fox Island

    TollyWally Senior Member

    Last year the powers that be mandated additional ethonal in the gasoline sold in my fair state. This was the start of many related troubles. I went through at least 5 sets of filters last summer and thought I had the problem well in hand. I have a stock BBC with a spreadbore Holley 4100.

    In the fall I went out and barely made it back in. I have already installed a dual filter system where I can switch from one filter to another while running. The fuel goes from these in line filters to the stock fuel/water seperator and finally to fine screens at the fuel bowl inlet.

    When I got back I thought the needle valves that control fuel into the bowl were clogged. I pulled those and then stripped the threads adjusting them.
    Sadly I was suddenly struck with some rather serious medical issues and couldn't get back to my boat for over 6 months. Yesterday I reassembled the carb and fooled with the float adjustment finally getting it so fuel wouldn't flow out of the level plugs on the side of the carb.

    I ran it for 20 or 30 minutes at the dock yesterday and things seemed fine. Today I ran it for 20 minutes at the dock and then took it out for a run. I left the hatch cover and aircleaner off to I could keep an eye on the carb , check for leaks etc. After leaving the harbor I took it for about a 3 mile run at various speeds. It seemed to run pretty good but needed a little tuning of the air mixture screws according to my vacuum guage.

    I came back into the Harbor and rafted up to enjoy a big annual Party for the fishboats heading north. Heading back to my dock after 4 or 5 hours rafted up it started fine and then died 150 yards from the raft. It was very hard to start, I got it to fire with ether and barely made it back to the dock.

    Tied to the dock I investigated and found that gas was just pouring down the secondaries at idle. I'm wondering if my original problem 6 months ago was flooding instead of clogging. In any event I am a little puzzled as to what to do next. Money is a little tight after my illness otherwise I'd probably just have my carb rebuilt. I've never rebuilt a carb before, all though I am sort of willing to try.

    So in summery I have
    a tank crud problem
    A carb problem
    not quite as much money as normal to throw at this.

    Suggestions and advice would be appreciated.
     
  2. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    The most likely culprit is of course the float itself or the tiny valve that should perfectly close when the fuel level is reached.
    If you have never dismantled the carb before, you need a good exploded view drawing to put it back together again. If needed, I can copy some pages from a book about overhauling carbs and post them here.
     
  3. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    I dont know the Holley 4100 - but i work on small carburettors every day of my life, i run a small tools plant hire business.

    I would think that a "carb kit" in your country should be cheap and hopefully easily obtainable.

    The biggest problems that i find is the fuel mixtures of today leaves a bit of residue, almost like a white powdery slimey film that clogges up the main jets.
    We remove float bowls very often to clean out and also find many faulty float - needle and seat problems.

    To me it sounds like you have a needle and seat problem which should be replaced and any internal "screens" that also block
    The old Tillotson carbs are notorious for internal screens

    I find that most any carb will run well if the above is ok
    with us a badly worn carb is not a problem - it simply wont alow the engine to idle well, but when the trottle valve opens the engine runs perfectly on its main jets. A worn carb is still easy to start as we start our engines with the throttle half open anyway

    hopefully this will shed a little light
     
  4. TollyWally
    Joined: Mar 2005
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    Location: Fox Island

    TollyWally Senior Member

    Thanks for the input everyone.

    CDK, I have a good exploded drawing but any information you might post will be appreciated.

    Manie B, I replaced both needle valve assemblies but I will be checking everything out again. I imagine a career such as yours makes you pretty valuable in a mechanical pinch. Thank you indeed for shedding a little light. I love your signature
     
  5. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    Tolly if you think the back float might have been the original problem, did you take a close look at the float to see if you dont have a pin hole(If its a Copper air filled chamber) or if its the Cork float, sometimes the clamp comes loose from the cork and the float will jamb up high holding the Needle open.

    IE; I think you might have a mechanical problem with that back float.

    Manie, have you come up with a Chemical that will clean that White gooey stuff out?
    We have that with all kinds machinery all over the contry and nobody has mentioned any additive or wash for it yet.
     
  6. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    What i have found to work for me is to strip the carb down and soak it overnight in petrol (gasoline) then brush very clean with paint brush, and blow out with compressed air.

    Lately 90% of my problems are carburettor.
    The problem is with the down turn of the economy rentals are low, i try to rotate my machines when and where i can, but it is not always possible. So i end up with machines standing for months and not going out to customers. I now make sure that when a machine comes back in, we run it until the carb is dry and then empty the fuel tank out. When the carb is left standing dry and empty there is definately less problems next time you fill up and start. Our **** fuel goes cloudy in the tank, if left standing for a couple of months. I am not sure why but it seems like the alcohol and fuel seperate - FACT IS the engine is a ***** to start with old fuel and runs badly.

    I would suggest to boat owners (two OR four stroke engines) to install a fuel shut off valve on the fuel tank and to run the engine until dry. I feel that a "winterizing" approach is always better if a boat is going to stand long. Then keep fuel in 5 litre (one gallon) tanks so that you dont have too much fuel in your built in tanks. Extra fuel goes to your car anyway.










    jeez when is this ecomony gonna pick up:(

    anybody want to hire compaction machines :D
     
  7. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    I have a construction business with multiple equipments of all types and the fuel quality is terrible. Two or three times my diesel trucks have had to get their fuel systems purge. Chainsaw have problem starting and gas won't perform properly. Between the water, ethanol, dirt, fuel supplier adding whatever to extend fuels. All my mechanic friends are making a fortune.

    So some ideas to lessen problems.
    Don't buy from the cheapest supplier. Buy Name brand.
    Use something like Baja filter to filter going into tank
    Install water separator,
    Install another filter
    Install visual filter on return line
    Replace hoses if necessary to make it Ethanol compatible
    Don't let fuel sit
    Use smaller multiple tanks instead of one big tank
    Running engine dry as stated above, though not recommended before might be a good idea.
    If I am not going to run engine for a while I pour wd40 into carb , float area and cylinders.

    I am sure there are others, but these come to mind
     
  8. Frosty

    Frosty Previous Member

    Your making this hard for yourself.--Google holly carbs, there is more information on those than you could ever want.
     
  9. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    Sounds like it may be one or more power enrichment valves stuck open. After you left the dock, you no doubt opened the throttles to get up on plane. This induces a sharp increase in manifold pressure which triggers the power valves to open. In normal operation these should only open briefly. If they are faulty, (if the have dried out hardened diaphragms, for instance) they may close too slowly or not at all, flooding the engine out. The power valves are located on the primary side metering block, which is between the primary side float bowl ***'y and the throttle body.

    Jimbo
     
    Last edited: Jun 27, 2009
  10. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Some of this may be related to which carb you have, but most is probably ethanol related.

    Ethanol has created a whole new set of problems. The rubbers, some gasket materials and coatings are being effected by this stuff. Coatings are being stripped, rubbers, plastics and gaskets melt, etc.

    The first thing you should do is replace the fuel lines with ethanol suitable lines, then a rebuild kit for the carb. Rebuild the carb, including the diaphragms in pumps or power valve seals.

    With close inspection you'll see little balls of rubber, plastic and gasket material, in the obvious collection areas, within the carb.

    This is the carb, I'm assuming you have.

    [​IMG]

    It's the 650 CFM electric choke, vacuum secondary (universal application, replacement for the Quadra-Jet). If yours looks different, provide the model number (usually stamped on the primary air horn).
     
  11. Frosty

    Frosty Previous Member

    You see the slider on the vacuum secondaries, you can but a small nut and bolt in there and make it into mechanical secondaries!!!!!!
     
  12. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    Not a good practice without doing either or both of the following:
    • Substituting different (higher flow) power enrichment valves
    • Changing the secondary float bowl assembly to one that includes a second accelerator pump.


    Otherwise, you will get a very bad 'lean bog' when you open the throttles.

    Holley makes plenty of mechanical secondary carburetors, but they always (AFAIK) have dual accelerator pumps, dual metering blocks and power enrichment valves on both primary and secondary sides.

    Jimbo
     
  13. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Damn, you beat me to it Jimbo . . .
     
  14. Jimbo1490
    Joined: Jun 2005
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    Location: Orlando, FL

    Jimbo1490 Senior Member

    Been round the block a few times with Holleys from little 2300's all the way to 850's and Dominators.

    And they do like to leak. :D

    Jimbo
     

  15. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Leaking has always been a problem. Hell, an 850 Dominator is a leak. A slow garden hose flow of fuel, into the intake. You can physically watch you gas gauge neddle move . . .

    The optional accessory metering blocks can help. Use a Demon and skip the fuss . . .
     
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