vaporlock
ok itsa 56 f100 with a crate 302 ,with a edelbrock 600 cfm carb,starts up great cold idles great everything but shut it off wait a minute r 2 and it creats a vapor cloud , then have tofloor it to restart
Lots of things to consider. Here is just a list of things I would check:
1. Are the floats, thus the fuel level in carburetor set correct?
2. Is the choke opening all the way up?
3. What kind of fuel pump are you using? If not using stock make sure the fuel pressure is not much more than 6 psi. If using an electric fuel pump and the pressure is higher than 6 psi, use a pressure regulator, and maybe look at installing a fuel return line back to your tank.
4. Install a phenolic, wood composite carb spacer between the carburetor and the intake manifold.
4. Add insulating material on you fuel line where it could be collecting heat from the engine. I use the black styrofoam tubing stuff HVAC guys use, it's cheap and works well for me.
5. There is also another consideration. Called "percolation", where the fuel boils off in the carburetor due to the heat. A good test might be to open the hood after a good road run and let the engine cool. If it starts easier, it could very well be that, which all the steps above could help you in that department too.
6. Ethanol fuel tends to have a lower boiling point. So if using it, try a couple tank fulls of non Ethanol. It works great in newer cars because the fuel is pressurized up to 60 psi.
7. Also make sure that your idle mix screws are set correctly and not too lean.
8. Make sure you are using the correct gas cap. For a 1956 stock tank, you would need a vented cap I believe.
Just a few ideas maybe.
1. Are the floats, thus the fuel level in carburetor set correct?
2. Is the choke opening all the way up?
3. What kind of fuel pump are you using? If not using stock make sure the fuel pressure is not much more than 6 psi. If using an electric fuel pump and the pressure is higher than 6 psi, use a pressure regulator, and maybe look at installing a fuel return line back to your tank.
4. Install a phenolic, wood composite carb spacer between the carburetor and the intake manifold.
4. Add insulating material on you fuel line where it could be collecting heat from the engine. I use the black styrofoam tubing stuff HVAC guys use, it's cheap and works well for me.
5. There is also another consideration. Called "percolation", where the fuel boils off in the carburetor due to the heat. A good test might be to open the hood after a good road run and let the engine cool. If it starts easier, it could very well be that, which all the steps above could help you in that department too.
6. Ethanol fuel tends to have a lower boiling point. So if using it, try a couple tank fulls of non Ethanol. It works great in newer cars because the fuel is pressurized up to 60 psi.
7. Also make sure that your idle mix screws are set correctly and not too lean.
8. Make sure you are using the correct gas cap. For a 1956 stock tank, you would need a vented cap I believe.
Just a few ideas maybe.
Last edited by hooler1; Mar 8, 2017 at 08:25 PM. Reason: added a line
ok great thanks i did install a pheneolic spacer thinking that could be it , its a stock mechanical pump , im running a mustang tank mounted under the bed, going to try the wrapping of the fuel line , that could be it i did reset the floats and cleaned everything and did adjustments , it did seem a bit rich though , and the choke is all the way open or as far as one of those goes anyway
OK, how about a lot more information and detailed pictures. Where is this vapor cloud? From the information you've presented so far, I am not convinced you have a vapor lock problem. How much fuel pressure are you running? Vapor lock usually shows up with an extremely hot environment.
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Like others your term "vapor cloud" confuses me? I think that you are saying that it is hard to restart with a warm engine and you have to go to WOT to clear out the flood. That can be caused by incorrect choke setting, a leaking carb power-valve or something else internal to the carb (crack, seal, etc.). It can also be caused by incorrect timing.
Like others your term "vapor cloud" confuses me? I think that you are saying that it is hard to restart with a warm engine and you have to go to WOT to clear out the flood. That can be caused by a leaking carb power-valve or something else internal to the carb (crack, seal, etc.). It can also be caused by incorrect timing.
All good points! How modified is this crate engine? Overbore could make it run hotter, and if you have a larger than stock cam, your initial timing needs could change quite a bit.
I was searching the internet on another subject, but stumbled upon this in Ford Muscle Forums. Good reading on the subject of difficult hot starting.
Hot Start Problem Fixed - Ford Muscle Forums : Ford Muscle Cars Tech Forum
Hot Start Problem Fixed - Ford Muscle Forums : Ford Muscle Cars Tech Forum
AMC experienced vapor lock and they cured it by putting a bypass filter in to keep the fuel moving. It had two outlets on the can, one for the carb and the other went to a return line to the tank. But this requires a restrictor in the outlet to the tank to keep the flow from causing a vacuum that pulls fuel out of the carb and stalling the engine.
Of course you could always take a time machine back to the '50s and '60s when they just wrapped their fuel lines with tin foil and clipped wooden clothes pins on the fuel line.
Later!
Mr. Ed
Of course you could always take a time machine back to the '50s and '60s when they just wrapped their fuel lines with tin foil and clipped wooden clothes pins on the fuel line.
Later!
Mr. Ed
AMC experienced vapor lock and they cured it by putting a bypass filter in to keep the fuel moving. It had two outlets on the can, one for the carb and the other went to a return line to the tank. But this requires a restrictor in the outlet to the tank to keep the flow from causing a vacuum that pulls fuel out of the carb and stalling the engine. Ed
For the bypass filter or wrapping the fuel line? 
Just goofing on you. They used the bypass filters in the late '70s and it caused problems because the restrictor I referred to was a little thing in the return fuel line and it got tossed when the line was ever replaced. It caused me heart aches in my Spirit because the aforementioned vacuum plagued my Spirit to the point I got rid of it (after I figured out why it kept stalling).
Later!
Mr. Ed

Just goofing on you. They used the bypass filters in the late '70s and it caused problems because the restrictor I referred to was a little thing in the return fuel line and it got tossed when the line was ever replaced. It caused me heart aches in my Spirit because the aforementioned vacuum plagued my Spirit to the point I got rid of it (after I figured out why it kept stalling).
Later!
Mr. Ed
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