Posted by Jack Smith on May 13, 1998 at 13:23:48:
In Reply to: Re: Vapor lock - help please posted by Jack Smith on May 13, 1998 at 03:22:11:
Well, there's that little % thing again, and this got cut off short. It was supposed to read:
Look at what causes vaporlock and that will give you the solutions. gasoline has a very high vapor
pressure, that is, it wants to jump out of the liquid state very readily and become a vapor. Add to this
the fact that today's pump gasolines contain even more volatile "environmentally helpful" additives,
like ethers, alcohols, etc. and you have a liquid that wants to evaporate with little help. The problem starts because the fuel delivery system from the tank to the carburetor was designed to move a liquid. When the temperature rises, the gas actually boils in the float bowl, making it impossible for the float/needle arrangement to keep the main jet supplied with liquid fuel. The result: vaporlock! To minimize this problem, The fuel pump can be mounted closer to the tank, or helped by a tank-mounted pump, so that the gas is being "pushed" rather than sucked the whole length of the truck, and the tank vent should be checked to make sure the pump is not pulling a partial vacuum on it. The fuel line can also be covered with an insulating jacket, and routed carefully away from heat sources. The carb itself can be mounted on an insulating block of bakelite or fiber, to help insulate it from the manifold. In worst cases, a "cool can" can be purchased from a speed shop, and is nothign more than a container that colls the gas flowing through it with water or ice. A good clean fix is to get a power steering cooler from a ford car, which consists of a short loop of 1/4" copper tubing with fins on it. Place it in the airstream under the truck, and route the fuel through it. The last thing is to buy the best gasoline you can. Consider Cam-2 racing gas in the summer, as it has evaporative inhibitors in it. Aviation gasoline also works well. Having done one or all of these things, keep a cell phone in the truck for bad times when none of them work!