Heat soak? Edelbrock carb & air gap

Discussion in 'Small Block Mopar Engine' started by 19blockhead72, Mar 26, 2017.

  1. 19blockhead72

    19blockhead72 FABO Gold Member FABO Gold Member

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    Hey fellows, having a minor problem here and there with a hot engine. It's only happened a couple times but is quite embarrassing to say the least. The other day I stopped at a buddy's for a half hour and went to leave. The car started fine backed out of the drive and started up the road, then I punched it. It started to go then ran out of fuel, spit, sputtered, and stalled. Pumped the gas and fired back up, no problems after that. This has happened a few times since I got it on the road a month ago.
    It's a mild 408 with a Edelbrock 750 vac. secondary, Edelbrock pump, Edelbrock air gap, new tank, new 3/8 fuel line, and a Jegs fuel filter. It's definitely a fuel issue and I'm guessing heat soak even though I've never experienced that before. What do you guys think, any cures?
     
    Last edited: Mar 26, 2017
  2. ScampMike

    ScampMike Despicable Damn Yankee FABO Gold Member

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    mechanical or electric fuel pump?
     
  3. Moparguy Ron

    Moparguy Ron Member

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    You're very likely right, I've got similar stories I could share. Ethanol in gasoline has made the problem worse. An easy test is to find some non-ethanol premium and give it a go. One common bit of advise is to install a Phenolic carb spacer, personally I've never had much success or seen much improvement from adding one. Luckily I do have a convenient service station that sells non ethanol premium, the only sure cure I've found.

    The above said, since non-ethanol isn't always convenient I've just added a Street Demon carb to the Duster with the poly body (the ignorant think it's a Thermoquad), seems to be a decent carb so far and it should deal with ethanol better that the classic AVS or AFB.

    Good Luck, Ron
     
    Last edited: Mar 26, 2017
  4. 19blockhead72

    19blockhead72 FABO Gold Member FABO Gold Member

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    Mechanical, I think 160 gph 6psi.
     
  5. 19blockhead72

    19blockhead72 FABO Gold Member FABO Gold Member

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    I have a insulater gasket that I haven't put on yet, just thought that air gap intake would eliminate the need.
     
  6. SBeeMan

    SBeeMan Well-Known Member

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    Use the insulater gasket. This is a common problem with the Eddy carbs.
    I have a '68 Super Bee running the Eddy carb till I can give the OEM Carter a replate & rebuild. I kept having a problem with the car starting after warm up,acted like vapor lock. I used a 1/2 wood spacer,problem fixed.
     
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    • 19blockhead72

      19blockhead72 FABO Gold Member FABO Gold Member

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      I'll put that on today to see if it helps. Our problem is a little different because my car starts back up no problem. My issue was punching shorty after hot start. Under normal driving conditions after hot start, no problem.
       
    • SBeeMan

      SBeeMan Well-Known Member

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      Mine would start and idle,rev fine,but would die when I put it in gear.
       
    • 19blockhead72

      19blockhead72 FABO Gold Member FABO Gold Member

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      Ok, that is pretty close to what I'm experiencing then.
       
      Last edited: Mar 26, 2017
    • T56MaxTorq

      T56MaxTorq Well-Known Member

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      Is the new tank vented? Insulate all fuel lines in the eng bay and keep away from exhaust. Look at all vacuum lines and ports on the carb to make sure nothing loosened up and is leaking vacuum. Carb spacers are great for keeping heat out
       
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      • kiss

        kiss Well-Known Member

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        This fixed my heat soak problems:
        - Home
         
      • brian6pac

        brian6pac Well-Known Member

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        Put a electric pump in the rear and it will fix all your problem. I fought the same problems a long time ago and gave up, so much easier to run a electric pump and a regulator never had another problem.
         
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        • T56MaxTorq

          T56MaxTorq Well-Known Member

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          Best part about an electric pump is that it will never leak fuel into the oil system like a mech pump can.
           
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          • 19blockhead72

            19blockhead72 FABO Gold Member FABO Gold Member

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            Thats an option but spent 150 bucks on the mechanical pump thats in it. If nothing else cures it then I'll look into this.
             
          • rumblefish360

            rumblefish360 so close yet so far away

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            FYI, I used an Edelbrock carb electric fuel pump at the rear of my car. EZ to wire in. Solved all issues of fuel. No regulator needed. My car has a return line which is in use. After I repaired it.
            The pump runs slightly quieter with the return line. FWIW.

            Oh! And yes, run the thicker carb to intake gasket if possible.
             
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            • TrailBeast

              TrailBeast Slightly Twisted Member

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              I agree with all the above and some of the possible cures, but let me add a little info to it.
              When warmed to temp and under normal driving conditions I can start my car up and watch the Air/Fuel ratio go into the 17's or higher for a minute or two with an Edelbrock.
              I have an insulator and a full circulating fuel system and it helped, but still there.
              The Edelbrock design lends itself to heat soak, and the fuel available just makes it worse.
               
            • brian6pac

              brian6pac Well-Known Member

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              As far as a noisy pump I always mount mine with the rubber from a hd muffler hanger then you don't even hear it at all. Grind off the rivets and bolt the pump to the rubber and the rubber to the rear shock crossmember, works great.
              35417.jpg
               
              Last edited: Mar 27, 2017
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              • dgibby

                dgibby Well-Known Member

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                I had the same problem with my eddy on my 340. Intermittently would act like it's running out of gas on hard acceleration even with a carb spacer. I went in and adjusted the floats a bit higher and it pretty much solved the problem.
                 
              • 19blockhead72

                19blockhead72 FABO Gold Member FABO Gold Member

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                Thats something that was on my mind. Did you set them at the factory specs? I believe it's roughly 7/16 of an inch?
                 
              • dgibby

                dgibby Well-Known Member

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                Used a 7/16 drill bit and had the floats barely touch them.
                 
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                • Bad Sport

                  Bad Sport HALF A BUBBLE OFF Staff Member FABO Gold Member

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                  Maybe you need jet extensions in the secondary bowl.
                   
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                  • 73Swinger18

                    73Swinger18 ✱ⓈⓌⒾⓃⒼⒺⓇ

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                    I fixed my heat problems with a spacer, aluminum heat shield, and a return line. I made the return line using a NAPA 3054 fuel filter that has a small orifice outlet that I hooked up to the line that was in the engine bay, previously used for the vapor cannister. This allows for the fuel to be constantly circulating and prevent vapor build up. I also insulated the fuel line coming from the mechanical pump and routed it away from heat the best I could.
                    IMG_20170326_105850.jpg IMG_20170326_105916.jpg
                     
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                    • AJ/FormS

                      AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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                      I don't get it
                      I have a Holley 750DP on my 360 on top of an AG. I run un-wrapped TTIs and aluminum heads . The water temp is a minimum of 205. I run the HO Carter pump with a 3/8 steel supply line, all the way into the tank. I run 87E10 exclusively.
                      I never ever have these kinds of problems.Not on the hottest days of summer nor under any kind of operation. Mind you we rarely see more than about 100 degrees in the shade.
                      I think I will get me an Edelbrock just to see what all the hullabaloo is about.
                      My answer is borrow a Holley, see what happens. Holleys have the bowls hanging out in the wind. And a great accelerator pump system.

                      As for me, I would not be looking at the fuel delivery system nor to the fuel. And with the AG, I find it difficult to think it might be hot-fuel.
                      But to prove it either take the hood off for a tankful, or pop the hood every time you park it. Time will tell.

                      Here is another thought; perhaps your engine is creating more heat than it needs to. Late timing will lead to the A/F charge not finishing it's burn in the cylinder. Then it may continue in the headers. The headers have no water jackets, so the heat goes into it's surroundings. I big cam will do the same.
                      If your engine is sucking hot underhood air, what would you expect. Take the hood off for a tankful.
                      Now here is the biggie;
                      If your supply line is within a few inches of a header pipe, move it! I put mine inside the frame all the way to the pump. I strapped my engine down and ran a really short rubber jumper across the gap. Insulation does very little when nothing is moving; it gets hot like everything else. Hot gas can flash to vapor as soon as it drops into the bowl. The sudden pressure change causes it to boil instantly.
                       
                    • rumblefish360

                      rumblefish360 so close yet so far away

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                      His Edelbrock carb does not and can not use jet extentions. The jets are in the floor of the carb.
                       
                    • 19blockhead72

                      19blockhead72 FABO Gold Member FABO Gold Member

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                      Although I have been working with ignition and will be upgrading it soon, I feel confident that my timing is dead on and the engine runs at a perfect 180 to 185. I just got done installing the insulated carb gasket so we will see if that helps. This issue only happened a couple times and hasn't effected starting or normal driving conditions. It only happened after starting it hot and then going wot shortly after.