Non existing Vapor lock Question ???

[BILL WZOREK]

Originally Posted by bobH

Can do, on the picture request. Temporary problem is, I'm on travel, and will not be home to get pictures for several days.
The factory plumbing at the carb is 3/8 steel tubing. I cut this, and put in a 3/8 Swagelok union. These are SS, and on the side of the union, I silver-soldered on a Swagelok fitting for 1/8 tubing. The 1/8 SS tubing runs to the gauge. There is an 'orifice' in this 1/8 line, to dampen the pulsations I observed from the fuel pump. In reality, the 'orifice' is a squashed section of the 1/8 tubing. I took ViseGrips and squeezed the 1/8, until the gauge read close to 'steady', and in this squashed area, the 1/8 tube is almost flattened. Nothing special about the gauge - it's a Stewart Warner fuel gauge, bought in the 1970's.
Please, no one take what I've done as 'advise'. This is simply what I've done, and there are 'safer' ways to do this. (another discussion)
As previously posted, I've had this vehicle, and this gauge setup for 40 years.
JMO

bobH:
No problem enjoy your Travel time / Vapor lock or the NON EXISTING
Vapor lock has been with us a long time.& it will be a little time before I implement the use of this on my 53 build.
Still gathering PARTS & THOUGHTSBut I want my wife to be able to drive the car with the Grand kids and not have to worry about Mechanical isues with the car.

[woodypecker]

I don not have vapor lock but I have a hot rod with no hood. Just remove your hood and many problems will disappear except when it rains.

[G.M.]

[QUOTE=FlatheadTed;725359]GM .? Facts !detail how the test were done .
Don't worry I am not with out experience, The cars I drive most, did have the so called VL .
Bob has put up a reasonable argument ,According to my research the boiling point of Alcohol is 172 F and its even higher in a vacuum ,like on the input side of the pump ,[/QUOTE

Ted this 10% fuel we have starts to boil at 125 and at 135 your fuel pump is on the edge of low pressure and stops pumping

Details on testing. When testing you have to perform multi tests using the same conditions every time. Just random every day driving don't give you the same conditions. I was one of the first to see the problem shortly after the ethanol was mixed with the gas and didn't know what was going on. The reason was I live where it's 90 degrees most of the time and was driving my 39 almost every day. I carried a handheld laser thermometer with me at all times. I started by thinking it was the dual exhaust pipes next the fuel tank heating the gas in the tank. I put aluminum heat sinks on the pipes which to my surprise drew the heat and the tank was no longer hot.
This didn't help. Next moved the fuel line in areas along the frame where it came close to the exhaust, still no help. Next insulated the fuel line from down at the frame right up to the fuel pump, no improvement. The fuel pump when hot is reading 135, raised the pump 1" with an adjustable push rod. Took a little longer to get hot. You have to realize all these old Fords have different fans and air flow patterns and venting at the rear of the engine. The 39 is one of the worst, location of fan, and sealed at the rear firewall area trapping heat with no where to go. Heat rises, hood is sealed on rear and every thing in the back is over 135 degrees. I put insulation under the pump which probly did the most to help cool the pump but after a longer period of time the pump still boiled the gas. I installed a computer fan with a funnel blowing air on the pump which was fitted with one of Skips aluminum impellers as a heat sink. This cured the heat problem on the pump. I had about 6 of these fans and it took the one that delivered the most CFM of air to do the job. When doing the tests I drove the same route on plus 90 degree days of about 30 miles each way stopping at the same place for lunch. Measuring the temperatures on the pump and other parts before starting the trip and as soon as we stopped for lunch, after lunch about 30 minutes from arrival and as soon as we returned. It is important to jump right out, raise the hood and get the temperatures before heat build up that happens after shut down. Early in the testing the carb base was hotter than the boiling point up to about 155 degrees. Installing Bob Shewman's 1/2" vented insulator between the carb base and the manifold dropped that temp to where it wasn't a problem. Don't forget the throats of carb base create a cooling effect when the base is not extremely hot and help cool the base. In airplanes carb ice forms in this area and before landing it is required to turn on the carb heater to prevent icing.
I also had a fuel pressure gauge in the line from the pump to the carb and could watch the fuel pressure at all times. As stated before the pressure is at the max the pump provides when cool but as the pump heats up the pressure drops, the hotter the pump gets the lower the fuel pressure until the pressure gets down in the 1/2 to 3/4 lb range and the vapors in the pump stop the pump from delivering gas. If you get all of the slop out of the fuel pump arm you can fine tune the pressure of the output with the length of the push rod. I find set at 4 lbs helps to prolong or over come the vapor lock for a while. It's very easy to install a gauge in the carb line and SEE what's going on as far as heat and it's effect on pressure. This takes all the guess work and "I thinks" out of solving problems. I figure there are 3 ways to over come the problem, an electric pump which I don't like, a small fuel return line with about a .100 ID after the pump back to the tank or fuel without ethanol. I have a fitting on the 39 for a return line and will try that in a month when I get back to Florida to see what happens, I "think" this will solve the problem. As mentioned before VL does not happen above 55 MPH because more cool fuel is being passed through the pump keeping it cool enough to prevent VL. JM 35 took pictures of the various gadgits I put on the engine in stages to find out step by step where the problem was. Maybe he will post the pictures. G.M.

You can go to www.pure-gas.com and click on your state to find ethanol free gas

[Old Henry]

Pictures of G.M.'s set up are in post #14 on this thread: http://fordbarn.com/forum/showthread.php?t=67218

[FlatheadTed]

Thanks ,GM ,Henry ,As I said I will do some testing of my own .My intentions are to try and simulate the hot conditions and fuel , I have The specs and setting up instructions of the Ford pump that I will post also .At the moment I am pushed for time ,but will be retiring soon so then maybe or a book . ,Apologise to bill for taking over his thread but it makes for a interesting discussion ,many different views .Maybe you could trigger your pump by a Temp sensor.

[bobH]

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Picture at carb, showing factory tubing plumbed to carb, and Swagelok union, with 1/8 SS tube that goes to the gauge.
And, picture of Stewart Warner fuel pressure gauge (1970's).
Red shop-rag is simply to provide contrasting background for picture.
The toggle switch to the left, is for the booster pump.