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  • Fuel System: Vapor locking?

    I have been having no trouble driving the 51 bullet-nose until it started getting hot as long as do not shut off it will keep running. After shutting off it will not start until it cools down. Again i am not a mechanic but from what i have read on this forum i am thinking vapor lock ? What options do i have to fix this problem. A retired mechanic suggested putting the old time wooden clothes pins on fuel line so the wood would help take some heat off has anyone heard of this. I would love to keep everything original.thanks in advance for the help i will receive now and in the future
    sigpic
    John Schuetter
    Jasper, IN

  • #2
    The last suspected vapor lock I recall having, was at a church social a couple of years ago. It was on one of those searing hot southern summer days. I had parked my '51 V8 Land Cruiser pointing into the sun on an already hot black asphalt parking lot. This car, has rarely ever failed to start. When it would not start this time, I went back into the church social hall. I got a couple of Styrofoam cups full of ice, placed them next to the fuel pump, and carburetor. I also poured a little cold water on the short coiled fuel line between the top mounted fuel pump and carb inlet. Then, I went back into the church, visited a little longer with some friends. After a little while, I returned to the car, and it fired right up.

    I know you had rather not have to jump through all those hoops to get going again, but this is a true story of how I handled what is usually a rare problem for me. One thing about the clothes pin idea. All it takes to return to "original," is to merely clip them off. Although, the theory is that the wooden pins would help dissipate heat, I'm thinking that some kind of metal clips would conduct the heat away even faster. You don't say if your '51 is a Champion or Commander V8. If it is a Champion 6, is your fuel pump heat shield still in place?
    John Clary
    Greer, SC

    SDC member since 1975

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    • #3
      Check a couple of things, make sure your heat riser is free to operate, if stuck closed will boil your gas and check your timing. At rest (static timing) you should be about 2 degrees retarded, when it starts the vacuum advance will establish the correct advance timing. Early 6 manifolds have a different arrangement than the later ones. It may also help to install a later manifold arrangement where as the hot exhaust gases do not go through the manifold to heat the fuel.

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      • #4
        Depending on how long it sits before you try starting again, your problem may be just the opposite. When shutting it off hot the carb may be heat soaking and peculating fuel into the engine and flooding it. I have a couple cars that will do this if its very hot and I try to restart after 5-10 minutes, starts OK before sitting 5 minutes or after cooling down. If this is the case, put the throttle to the floor then crank it, it should fire after a few cranks.

        Similar to the clothes pin trick, my dad folded a couple pieces of thin aluminum sheet around the fuel line near the carb making tabs or fins on his '53 Coupe. He says it works, it has never vapor locked since. Of course I don't remember it ever vapor locking before that either.

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        • #5
          John: It is a champion 6 and i just got home from work and you are correct it does not have the heat shield.is this something that i can get from one of our studebaker vendors or will i have to have it made by someone?thanks
          sigpic
          John Schuetter
          Jasper, IN

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          • #6
            Originally posted by jclary View Post
            The last suspected vapor lock I recall having, was at a church social a couple of years ago. It was on one of those searing hot southern summer days. I had parked my '51 V8 Land Cruiser pointing into the sun on an already hot black asphalt parking lot. This car, has rarely ever failed to start. When it would not start this time, I went back into the church social hall. I got a couple of Styrofoam cups full of ice, placed them next to the fuel pump, and carburetor. I also poured a little cold water on the short coiled fuel line between the top mounted fuel pump and carb inlet. Then, I went back into the church, visited a little longer with some friends. After a little while, I returned to the car, and it fired right up.

            I know you had rather not have to jump through all those hoops to get going again, but this is a true story of how I handled what is usually a rare problem for me. One thing about the clothes pin idea. All it takes to return to "original," is to merely clip them off. Although, the theory is that the wooden pins would help dissipate heat, I'm thinking that some kind of metal clips would conduct the heat away even faster. You don't say if your '51 is a Champion or Commander V8. If it is a Champion 6, is your fuel pump heat shield still in place?
            A CO-2 extinguisher would probably be far faster though it might put a crimp in your social life.

            ---------------------------------------

            The clothes pin concept makes no sense. Wood is not a good conductor of (to draw away) heat. If it has any useful effect it would be as an insulator. Under the hood the fuel likely comes in far cooler than the line it is running through. And the ambient air under the hood is likely equal to or warmer than the line itself. So, anything that would be intended to draw heat off the line would in fact likely actually cause it to conduct heat. It is the heat soak in the carburetor itself that is the primary problem. It boils the fuel off.

            Insulating the carburetor base from the hot manifold would be moving in the right direction. Ironically they actually make wooden carb. plates for this purpose (at least for 4 bbl.) http://pitstopusa.com/i-23915589-ede...hick-wood.html . But in general you have a radiator emitting 180-ish degree heat and a fan blowing it back onto the carburetor so that is a big problem right there. Years ago my step father had a friend with an early Econoline van. The carb base was very prone to warping. He ducted a dry air hose from the grill to the carb base and his problem was solved. I think properly placed the engine fan propelled hot air might even (by its motion) slightly draw cool air in the ducting even at idle.
            Last edited by wittsend; 07-28-2016, 03:09 PM.
            '64 Lark Type, powered by '85 Corvette L-98 (carburetor), 700R4, - CASO to the Max.

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            • #7
              One more opinion. My '53 Commander suffered from this, stop for gas, it wouldn't start, stall at a light, it wouldn't start. After trying an electric fuel pump and a couple other 'quick fixes' I installed a return line between the fuel pump and the carb, with a .040 restriction in it. The theory is that the pump keeps pulling cool fuel from the tank, so that the pump and lines are not as hot as the engine compartment, and the fuel in the carb doesn't boil away at a stop.

              Whatever the theory, my '53 no longer struggles to start on a short shut-down.

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              • #8
                wittsend:again i not a mechanic but what i understand your saying i may need to have radiator looked at. also then could it be the fuel i am putting in currently i am putting the highest octane i can get. i do have access to what they call rec. fuel? thanks
                sigpic
                John Schuetter
                Jasper, IN

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                • #9
                  A pint of diesel fuel in a tank of gas supposedly lowers the boil point of ethonol gas. I also insulated the steel lines from the pump to the carb. Hasn't vapor locked lately but not sure what corrected the problem.

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                  • #10
                    Originally posted by 51champ View Post
                    wittsend:again i not a mechanic but what i understand your saying i may need to have radiator looked at. also then could it be the fuel i am putting in currently i am putting the highest octane i can get. i do have access to what they call rec. fuel? thanks
                    No, not at all. I was merely stating the heat that all and any car radiators put out blows hot air across the carburetor. This along with the heat emitted from the engine itself was heating the carburetor and likely causing the gas to boil.

                    I was also countering the notion that cloths pins would conduct heat out of the fuel line and cool the fuel. What I was saying was "even if" cloths pin were good at conducting and dissipating heat (and they aren't) the temperature of the fuel in the line is still likely cooler that the hot radiator air blowing across it. So, there is no way the fuel would be cooler, it would only be hotter. And that only based on the false premise that cloths pins would draw heat from the fuel line and somehow dissipate it into the even hotter air surrounding it.
                    '64 Lark Type, powered by '85 Corvette L-98 (carburetor), 700R4, - CASO to the Max.

                    Comment


                    • #11
                      I was reading this and was going to recommend putting a quart of diesel in the gas tank but someone already mentioned that trick . So I will also recommend this . I had the problem on several old vehicles and used diesel to correct it . The latest was a 47 M16 Stude truck . I know it sounds crazy but it works . Our new government mandated fuels have a low boiling point and the diesel helps raise the temp level .

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                      • #12
                        I used to have problems all the time with my 51. In my opinion if your mechanical fuel pump is not at 100% of specs you will never solve the problem entirely. It has to put out enough volume and pressure. The specs are in the shop manual. The reason, I believe, this is so important is because of the location of the fuel pump on 51-54 V8's. It gets a lot of heat from the radiator and the engine. Not only that, heat rises. The second thing is to stay away from ethanol gas. As a person who makes his living with corn, it is hard for me to say that. It is reality though that carbureted engines do not tolerate ethanol fuel very well. My 51 with regular gas and a good fuel pump does not vapor lock in even the hottest weather. However.... I do have a pull through electric fuel pump installed. If the fuel pump starts to get weak and this does happen about every 5 years it will start to have problems again. If the car stumbles or won't start, kick on the electric for a second and she fires right up. Same thing for ethanol. Sometimes all I can buy in corn country is ethanol gas. In that case all bets are off because of the mentioned problem about the location of the fuel pump. I those times I just use the electric pump as a back up in high heat conditions.
                        1962 Champ

                        51 Commander 4 door

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                        • #13
                          Originally posted by Kurt View Post
                          I used to have problems all the time with my 51. In my opinion if your mechanical fuel pump is not at 100% of specs you will never solve the problem entirely. It has to put out enough volume and pressure. The specs are in the shop manual. The reason, I believe, this is so important is because of the location of the fuel pump on 51-54 V8's. It gets a lot of heat from the radiator and the engine. Not only that, heat rises. The second thing is to stay away from ethanol gas. As a person who makes his living with corn, it is hard for me to say that. It is reality though that carbureted engines do not tolerate ethanol fuel very well. My 51 with regular gas and a good fuel pump does not vapor lock in even the hottest weather. However.... I do have a pull through electric fuel pump installed. If the fuel pump starts to get weak and this does happen about every 5 years it will start to have problems again. If the car stumbles or won't start, kick on the electric for a second and she fires right up. Same thing for ethanol. Sometimes all I can buy in corn country is ethanol gas. In that case all bets are off because of the mentioned problem about the location of the fuel pump. I those times I just use the electric pump as a back up in high heat conditions.
                          Try opening the hood when you stop for a while. The engine gets hot and the modern gas with a low vapor pressure just boils away. Opening the hood will allow heat to escape the engine compartment. You should have a heat shield but it won't help this problem.

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                          • #14
                            Originally posted by Jeffry Cassel View Post
                            Try opening the hood when you stop for a while. The engine gets hot and the modern gas with a low vapor pressure just boils away. Opening the hood will allow heat to escape the engine compartment. You should have a heat shield but it won't help this problem.
                            That's what I did to help the restart problem. It helped, but my Studebakers still don't start like they did with the real gas from the 60's and 70's. I'm going to make a heat shield to see if that helps the carb, and I'm going to find some wrap for the exhaust manifold to keep the heat in the manifold.

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                            • #15
                              Think the wooden spacer would help Wife's 57 Hawk, but the 62 Lark Turbo car is a different can of worms. been thinking about ducting cool outside air thru 2 Bilge spaces fans onto front of carb to keep temp down no room for spacer there anything over 1/4 inch causes interference with hood. high CFM axial flo fans have good flo rating and could help push hot air out from under engine compartment. Happy Motoring , Doofus

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