How do you stop vapor lock?

[steve s]

[Tinbasher]

Heat is the problem. So I would put a 1" spacer in between the carb and the intake to get the carb away from the manifold. Then move the fuel lines away from the exhaust. Use a heat deflector plate under the car base, 3/16 aluminum plate works well. make it about twice the size of the base of the carb. If that fails Google Vapour Lock.
John Poole

[Clem Clement]

Goodness!! let me help you with the use of wooden clothes pins. I use a rack of them. They have never failed me. Every lady who comes by starts a conversation with me about them pins...

[updraught]

Seems to be a new book about this.

http://blog.hemmings.com/index.php/2...-classic-cars/

http://fifthaveinternetgarage.blogsp...-car-wont.html

[stouchton]

Some ideas:

Use header wrap (looks like they get "cherry")

Modify a starter shield (soft type) to insulate carb

Improve airflow under hood - use electric aux fan if necessary. If underhood temps too high, you will be sore pressed to solve. Methinks the cherry headers are producing too much heat under hood. Maybe even a special deflector to force air under hood while driving?? Might interfere with radiator air flow though.......

Insulate fuel line and move away from heat

Use infra-red viewing camera to see what is really getting hot - I use one and it really tells the tale. You could see if it is carb or fuel line (or both). You could try a infra red thermometer, but they do not "pin point" very well.

Give the engine as much initial timing it will take - advanced timing keeps heat in the block, retarded timing produces more heat in exhaust system.

Did this just start??? Or has it been an issue since day one?

Does outside air temp effect the situation?

Clothespin - conducts heat better than air - clamped to a fuel line acts as a heat sink to pull heat from fuel line (not much...). If clothespin is close to header can work the other way!!!

[emf]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by stouchton

Some ideas:

Clothespin - conducts heat better than air - clamped to a fuel line acts as a heat sink to pull heat from fuel line (not much...). If clothespin is close to header can work the other way!!!

As I asked above, please explain the science behind your statement. A good test would be to use your infra-red camera to show the temperature gradient between the gas line and the wooden clothespin. there is a reason cellulose is used as insulation. It does not conduct heat well! Heat sinks are just that, they conduct heat away from the source extremely well...

Frank

[George Miller]

Originally Posted by emf

I wish someone would explain the science behind the clothespins. Wood is not a good conductor of heat. Science tells me that air is a much better insulator and therefore, a loosely attached sleeve of tin foil with air between it and the gas line is much better. I think the clothespin idea is smoke and mirrors. Hear come the slings and arrows...

Frank

Maybe the clothespins cause turbulence in the air, which puts more air on the line. Other wise I can not see how it could work.

[captndan]

I don't know the science behind these fixes. I do know that in the 50's tin foil and cloth spins did work. And that was at 5000 feet and up.

[stouchton]

Originally Posted by emf

As I asked above, please explain the science behind your statement. A good test would be to use your infra-red camera to show the temperature gradient between the gas line and the wooden clothespin. there is a reason cellulose is used as insulation. It does not conduct heat well! Heat sinks are just that, they conduct heat away from the source extremely well...

Frank

Thermal transfer (resistivity/conductivity) is a function of density (along with thickness, surface area and absorption coefficient).

[4port]

If you drink Coke as I do, pour a Pepsi on the carb. A bottled water will work in a pinch.

[CarlG]

Refering to a Pepsi as a Coke?? Blasphemy!

[dean from bozeman]

Whether it is the barn or our house, we used foam insulation and it really keeps the heat in...except where the rafters are. In the winter when there is a light snow on the roof you can see exactly where the rafters are from the outside. Therefore, wood is a conductor of heat.

On the gas line clothespins would conduct heat away (unless they are near the manifold which has been stated) from the gas line. Though clothespins might work, Old Man-NorCal's idea of using oven door gasket is brilliant.

[Royce P]

It is kind of like Marvel Mystery Oil. People swear clothespins fix vapor lock - with no science to explain it.

Originally Posted by emf

I wish someone would explain the science behind the clothespins. Wood is not a good conductor of heat. Science tells me that air is a much better insulator and therefore, a loosely attached sleeve of tin foil with air between it and the gas line is much better. I think the clothespin idea is smoke and mirrors. Hear come the slings and arrows...

Frank

[Ak Sourdough]

The insulation value of spruce wood (log house or cabin) is around R1.5 per inch of thickness compared to fiberglass at around R3.1 and foam from around R3 to R7 depending on the type of foam. Nearly everything is a conductor of heat, some things obviously much better than others.

The object here, it seems to me, is to keep the fuel from boiling and turning to vapor in the fuel line. On a very hot day or in traffic all of the fuel will be hot, including the fuel in the tank sitting way up high and behind the exhaust. It is probably very close to changing from liquid to vapor as it leaves the tank.

I believe the answers to your problem have already been suggested here. If it were mine, I would wrap the header to reduce under hood temperature as much as possible and buy or build an inline cooler that you can pack with ice or cold water when the need arises.

Living in Alaska all my life I have never experienced a vapor lock, but I understand how frustrating it could be. Good luck.

[Ak Sourdough]

Another thought I just had would be to run the fuel line as directly (short) as possible to the carburetor as you can and eliminate any humps in the line. That way it may be possible for any vapor that forms in the line to travel back upstream and return to the tank. Any place where the return flow would have to turn down instead if up might stop return flow of the bubbles. Also, a transparent fuel line might let you view the bubbles.

[jg61hawk]

In the Studebaker Club magazine it was suggested a pint of diesel fuel to a full tank (20 gallons) of gasoline; so in your A 10 gallons is full so 8 oz of diesel. Diesel and Marvel Mystery Oil increase the temperature that is needed to boil away the fuel. I assume 2 cycle oil may do the same, but diesel was written about by an expert in that club.

[Dick Steinkamp]

For you that believe that ethanol is a cause of vapor lock, the opposite is actually true. Ethanol boils at 173F. Gasoline starts boiling at 90-100F. In addition, gasoline is substantially easier to vaporize than ethanol.

http://www.txideafarm.com/ethanol_fu...s_and_data.pdf

Ethanol certainly has some down sides, but contributing to vapor lock is not one of them. In fact, the more ethanol in the gasoline, the LESS chance you have of experiencing vapor lock.

[tbirdtbird]

the problem is the mixture has various boiling points...blended fuels no longer exhibit the properties of the individual components...
https://tsocorpsite.files.wordpress....ol-and-gas.pdf

which states that the boiling point can range from 85 – 392°F, depending on many factors

[Tom Wesenberg]

Originally Posted by jg61hawk

In the Studebaker Club magazine it was suggested a pint of diesel fuel to a full tank (20 gallons) of gasoline; so in your A 10 gallons is full so 8 oz of diesel. Diesel and Marvel Mystery Oil increase the temperature that is needed to boil away the fuel. I assume 2 cycle oil may do the same, but diesel was written about by an expert in that club.

I'm going to try that in my Studebaker, because it takes some cranking after it sets for 5 minutes to a couple hours when hot. My Model A has been fine since I use only the good gas, but it had vapor lock with the ethanol crap in it.

[txkhog]

Could you add a pressure bypass line up next to the carb inlet and return to the gas tank. The bypass will keep gas circulating in the lines any vapor will be vented out the gas cap. This is what is done on some modern cars.

GDG