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Best way of fixing vapor locked carb?

Discussion in 'The Hokey Ass Message Board' started by Graham M, May 27, 2011.

  1. Graham M
    Joined: Apr 17, 2011
    Posts: 406

    Graham M
    from Calgary AB

    Hey guys, I have a '64 International B160 w/the 304ci V8. The OEM 2barrel Holley Carb vapor locks itself whenever the engine gets even moderately warm.

    From there I usually have to wait about an hour for the carb & outer engine to cool itself down before it'll start again. Needless to say this is incredibly frustrating, especially after stopping to get gas. :mad:

    Is there any way to remediate this? I was planning on replacing the carb with a much more modern one, but the mounting pattern on the old carb is very irregular, and finding an adapter is proving quite difficult. (OEM mounting bracket is 3.5" deep by 5" wide)

    Any suggestions would be very much appreciated. Thanks a ton for reading this and offering any help or tips you can. :)
  2. Find a way to cool the fuel line, perhaps move it away from the engine or get the fuel pump to provide more pressure, say an electric unit.
  3. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,428

    Von Rigg Fink
    from Garage sure its not vapor locking in the fuel lines...are the fuel lines close to the exhaust manifold or engine block for too long of a run?

    2nd..a heat sink under the carb can help..and a non metalic spacer to move the carb up off the manifold some..

    I have seen where guys will machine a thin aluminum plate to go under the carb to disapate the heat

    I have also seen a shit load of clothes pins added to a fuel line to disapate heat..and tin foil on fuel lines..the list goes on
  4. Graham M
    Joined: Apr 17, 2011
    Posts: 406

    Graham M
    from Calgary AB

    Ah thanks, the fuel line just hovers over the block from the valve cover over to the carb, so I'll bend it out of the way, coat it with some thermally resistant coverings. If that doesn't work I'll replace the stock fuel pump.

    Any suggestions for non-metallic carb spacers? Its such an odd size, and all the ones I've seen are just aluminum.

  5. Is it by chance 5 1/8" not 5"
    Holley has them 3 1/2 - 5 1/8 - 1/4 thick
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  6. gibraltar72
    Joined: Jan 21, 2011
    Posts: 260

    from Osseo Mi.

    they used to make spacers out of a plastic called Phenolic Resin I'm sure a piece of that coud be easily fabbed that would act as a heat shield to break metal to metal heat transfer.
  7. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,309

    Atwater Mike

    Phenolic (available at metal/plastics distributors) and similar 'plastics' (resin cured, etc.)
    I've even seen hard woods used! (oak, maple, hard cherry, etc.) Machines easily, sands smooth as glass.
    I'd 'scoff', but I build and fly control line model airplanes, and use hard woods a lot (mounting engines, hard points for landing gear, etc.)

    Wood is good.
  8. SinisterCustom
    Joined: Feb 18, 2004
    Posts: 8,269


    Either that or wood.....:)
  9. brad chevy
    Joined: Nov 22, 2009
    Posts: 2,627

    brad chevy

    Put a cool can on it and that should cure the problem,are you sure its vapor loc? never had an international to vapor-loc,just Mopars.
  10. badshifter
    Joined: Apr 28, 2006
    Posts: 3,278


    It's not usually the carb. Cool (as in not boiling) fuel fed into a hot carb will not continuously boil off for an hour. It's usually at or before the fuel pump on the suction side of the fuel system that vapor lock occurs. The pump is unable to create enough vacuum to pull the fuel from the tank. Check your lines from the pump back. A weak/old fuel pump can make the problem worse. An electric pump near the tank so the line is under pressure usually cures vapor lock problems.
  11. Cymro
    Joined: Jul 1, 2008
    Posts: 700


    Also check all flexible fuel lines for internal collapse and loose flaps of rubber that may restrict flow. I know this sounds stupid but it's happened to me a couple of times and the pipes looked fine externally and posed no restriction to an air line. Just a thought.
  12. racer32
    Joined: Sep 22, 2007
    Posts: 745


    Used to have a Jeep that vapor locked all the time in the summer. I mounted a cheap electric pump back by the tank, and would flip the switch to turn it on when it got hot.
  13. oldpaint
    Joined: Jul 25, 2009
    Posts: 357


    I had a fuel line drop down on the exhaust pipe at the rear of the car. Car would run fine on short trips and even long trips as long as it was moving at speed. On a longer trip if I had to sit in traffic it would vapor lock.

    A clip that held the fuel line had failed. After reattaching the line no more problems.
    So make sure your fuel line is also away from your exhaust pipe and muffler.
  14. outlaw256
    Joined: Jun 26, 2008
    Posts: 2,023


    i thought my 62 galaxie was vapor locking also, but i read somewhere that the fuel we now try to use can percolate and disapate and real quick and almost leave a fuel bowl empty in less than 5 min.i dont know if thats true or not, but i do know this crap wont burn like the old fuel would.
  15. tommy
    Joined: Mar 3, 2001
    Posts: 14,758

    Member Emeritus

    Exactly what does that mean to you?? Does it mean that it will start right away if you give it a shot of fuel? Then it is possible.

    When I was young, I was told all the same stories... a no start when warm was vapor lock. I tried all the wives tales. I had clothes pins and aluminum foil all over the fuel line from the fuel pump to the carb.

    I stopped to look at an engine and it would not start. The guy with the engine said wait a sec, went into the garage and brought out a CO2 fire extinguisher. He put his cap over the carb and gave the ign. coil on the intake a long blast. He built up a pile of snow on it. When it melted he said start it up. It started instantly just like it did when cold. It was not vapor locking at all. I had a bad coil and was chasing wild geese for months. That was in 1965 and I have never seen a documented case of vapor lock since. I've read all of the stories.

    A no start when warm is not always a vapor lock.
    BJR and C. John Stutzer like this.
  16. grovedawg
    Joined: Oct 20, 2009
    Posts: 451

    from Heber, UT

    That's great advice too!
  17. Two things
    1. electric fuel pump will solve any vapor lock problem.
    2. on my old travelall I had similar problems that would strand me then work again. turned out to be an dirty inline fuel filter. after the fix I bought a spare and never had to use it
  18. I make carb spacers out of birch plywood.
    Cut the metal line and replace it with rubber hose.
    Or insulate it with black hot water insulation tubing from Lowes or HD and tape it with aluminum duct tape (not 200 mph stuff).

    Attached Files:

  19. TDak
    Joined: Oct 20, 2006
    Posts: 36

    from Oshkosh

    I had the same problem even with an electric fuel pump. Wrapping the fuel line with an insulation wrap fixed it. Good luck.
  20. There is a fella retired from Alcoa down in PA. that is making a Cool Carb spacer that has gotten a lot of good press. In fact Dick Spadaro is stocking the ones for the 97's and 94's. He is making a bunchof different gaskets now for other makes. No smoke and mirrors really works. On his truck, when checked with a laser, the engine was at 210 but his carb was at 90. The fellas name is Dennis and can be reached at 717 309 0719 FWIW.
  21. carbking
    Joined: Dec 20, 2008
    Posts: 2,914


    As mentioned earlier in this thread, coil is more likely the culprit. However, a LOW PRESSURE electric pump will cure many ills. A high pressure pump may simply add more problems.

  22. Fuel injection!:p

    Just kidding. I used to just wrap tin foil on the fuel lines when moving the fuel lines on something was too much of a PITA. Always worked like a charm but looked micky-moused.
  23. If it is vapor lock I have read that using an electric pump WITH a return line to the tank is the hot ticket (pun intended). With a return line system the fuel is always circulating. First things first though ... verify it isn't your coil and make sure your lines are well away from a heat source/insulated.
  24. Novadude55
    Joined: Nov 10, 2009
    Posts: 2,352

    from CA

    I would be thinking coil also, Graham you never mentioned checking for spark, if it stalls as often as you indicated, next time check for spark, post back and let us know..
  25. Clik
    Joined: Jul 1, 2009
    Posts: 1,882


    I have heard about "vapor lock" my whole motoring life and have yet to have anyone give me a logical explanation of what it's supposed to be.

    The explanations I have gotten defy physics.
  26. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,898


    Same here.
  27. plym_46
    Joined: Sep 8, 2005
    Posts: 4,008

    from central NY

    Please explain vapor lock to me. Please explain how a bubble of air or vaporized fuel moving toward an atmospherically vented container can block a liquid under pressure in the same vessel. If this is possible how do we bleed our brakes????

    Fuel can perculate (act as a heat sink, vaporize and or evaporate from the carb, or it can expand from heat and over fill the float bowl creating a flooded engine. (try running a slightly lowered float level) Fuel lines and fittings between the tank and the pump can leak air and cause the fuel pump to try to pump air, which it doesn't do well, but a bubble of air on the pressure side of the pump can not physically block the fuel from moving. Any rubber parts on the suction side of the pump need to be checked to make sure they are not collapsing due to suction.

    And ford flatheads with thier fuel pumps located above the level of fuel in the tank, and on top of the heat from the engine, usually have a hard time sucking gas up hill. Other cars that have thier fuel pumps lower than or level with the median level of fuel in the tank seem not to have these types of problems.

    if you need further proof that air, gas, or vapor will move readily through a fluid toward the atmosphere, pop a beer while you're thinking about it.
  28. Clik
    Joined: Jul 1, 2009
    Posts: 1,882


    In my business we use vacuum trucks to pump water from various underground pits, tanks, vaults, etcetera. I try to think of vacuum as non existent. You are simply creating a void for the atmospheric pressure to push liquid or air to. The most you can practically depend on a vacuum pump pulling a column of water is about 30'. That's because you are limited by the atmospheric pressure that is pushing the water up the hose. If you introduce air into the column of water by drilling a 1/4" hole somehwere along it's length, it will suck air, form bubbles and the column of water will lift higher. That's because the column of water is now lighter and the atmospheric pressure will push it higher. This would seem to blow the theories of vapor lock due to gasoline boiling in the fuel line above or near the manifold. That would just make the column even lighter and easier for the pump to push.
  29. Carguy365-24-7
    Joined: Mar 25, 2006
    Posts: 909


    I had a problem with vaporlock with my 216 .I switched to non-ethanol gas and my problem went away....PAUL
  30. Graham M
    Joined: Apr 17, 2011
    Posts: 406

    Graham M
    from Calgary AB

    Hey guys, first off, thanks a TON for the responses. I've bookmarked this page just from the good advice alone. Man this is by far the most helpful forum I've ever seen, ever.

    HUGE thanks to the HAMB guys!

    Anyway, I followed the advise, and bought some 3/8" Fuel hose, and used that to cover the fuel line all the way down to the fuel pump.

    (I should take a picture of the fuel line routing, I dont think you guys would believe it otherwise; its incredible) but it follows the engine from the oil pan all the way up in front of the block, across the valve cover then over to the carb, all within 1" of the engine. Needless to say it has PLENTY of opportunity to get hot.

    I think I've cured it now, but have yet to take it on any long drives where the engine can get really hot and see for sure.

    I've taken down the numbers & names of the people offering to help with the carb spacers, so if this doesn't pan out then I'll contact everybody that has offered their help.

    Again, thanks a ton for all your help!!

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