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Thickness Of Carb Gasket

Discussion in 'Early CJ5 and CJ6 Tech' started by mickeykelley, Jun 5, 2017.

  1. mickeykelley

    mickeykelley Well-Known Member

    When I got my carb back from the restorer, he included what I think of as a normal thickness gasket between the carb and manifold. However, over on the 2a site, I was reading about a guy having an issue of apparent gas draining back into the tank, thus causing more cranking to refill the carb, etc. Someone mentioned there should be a thick (1/4") gasket which helps insulate the carb and keeps the gas from boiling out when you shut it off. Anyone ever hear of this? When Willie sits for a couple days, it takes more cranks to start, and if sitting a couple weeks, it's lots of cranking. This is on a stock F134.
     
  2. Rick Whitson

    Rick Whitson Detroit Area 2024 Sponsor 2022 Sponsor

    I have a standard gasket, that came with a gasket kit, on mine and it starts too soon, before the oil light goes off. I have a switch on it and crank it until the oil light goes off, then flip the switch and it starts. My Jeep is at my cabin and sits for weeks at a time. When it is warm I just bump the starter and it lights up, I don't have a fuel boiling problem.
     
  3. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    I've seen the thick ones used from time to time, but it never made any difference to me in my climate zone.

    As for excessive cranking, the M38A1 fuel pump has a manual priming lever and is interchangeable with CJ5 - if it is important to you.
     
  4. radshooter

    radshooter Member

    Is this really a problem as long as the battery is in good shape? Mine does the same thing. It seems I have to crank less in the summer though. Rarely drive it in winter.
     
  5. Glenn

    Glenn Kinda grumpy old man Staff Member

    How long measured in seconds does this actually take? You have the YF, right?
     
  6. mickeykelley

    mickeykelley Well-Known Member

    Yes the YF. Seconds are measured in eternities. I'll have to count next time.

    I know part of it is we are all used to the modern computer adjusting things, just the right amount of spark, gas, air, etc.

    What is the word I'm looking for????......oh that's right, spoiled, instant gratification, and a few others.

    The other day I forgot to close the choke and was wondering why it was running ruff? Then realized the old computer forgot to push the knob back in. Computer must be getting Alzheimer's.
     
  7. Glenn

    Glenn Kinda grumpy old man Staff Member

    Believe me, I hear ya. :) The hotter the weather the worse the fuel evaporation problem can be, so that might be part of the issue. I personally don't see how gas could drain back from the carb bowl. As far as the thicker gasket, did the guy say if it was on a flathead?
     
  8. scoutpilot

    scoutpilot Member

    Use the standard base gasket. If a thicker gasket was the solution it would have been figured out 60 years ago. Gasoline can not drain back from the bowl. Excessive engine heat from 1. Bored .50+ over. 2. Timing too far advanced. 3. Excessive Lean Mixture, will cause the fuel in the bowl to evaporate faster. Old gaskets don’t help this situation. The best way to reawaken a motor seldom used is to pour a small amount of gas down the throat and start with full choke. Other than that, find a military fuel pump with the priming lever.
     
  9. garage gnome

    garage gnome ECJ5 welder

    I had this problem too and it turned out to be bad valves in the fuel pump. Are you using the glass bowl reproductions?
     
  10. radshooter

    radshooter Member

    I guess I thought it was a normal occurrence. Reminds me of growing up on the farm. All of our trucks and pickups started that way. Pull the choke, pump the accelerator pedal a few times and either turn the key or push the starter button with your foot. Repeat as necessary until the motor started.

    On my CJ, I hold the key for 2 or 3 seconds then stop to let the starter cool a bit. It will usually start after the second or third try. After driving a bit it will crank right up. Just like the old '48 and '54 trucks back home.
     
    mayday likes this.
  11. mickeykelley

    mickeykelley Well-Known Member

    I guess another solution is to add an inline electric pump and a switch to turn it on for a few seconds if it been sitting.
     
  12. mayday

    mayday Sponsor

    My all stock 58 cj5 just rebuilt parts by me. 3 pumps set choke starts with in 2-4 sec of cranking. 6 volt also. I'm on my second yf rebuild in 5 years pump was rebuilt 2 years ago.
     
  13. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    A solution looking for a problem.

    A couple of engine revolutions will fill and pressurize the fuel pump diaphragm, storing reserve energy in the diaphragm spring.
    Extra cranking contributes nothing until that fuel is dispensed.

    So, if the carb bowl really was dry, one could crank a little, wait, then crank a little more, intermittantly.