What is the best way to prevent Vapor Lock in this heat??

Are you sure that it is "vapor lock" and not trash in the line? Ole Willie had a little bout with the fuel supply a few years ago. I drained the gas from the tank and removed the shut off valve from the fire wall (indented like yours). There was alot of flakey rust. I cleaned the tank out the best I could and have not had any problem since.
 
Hi
Looking at the eng(which is good looking) the fuel line seems to go up hill when it comes off the firewall. If that could decline slightly on its way to the carbit might help. Would not detack from looks. Just an idea!!
 
99% sure, i have a indented fire wall and side bowl carb so the junk goes into their,
but ya never know. Going to try to insulate the line to see and use a better gas.,
 
If you had a bad cap you would know it if you tried to take it off, and it would start again when you lost the vacuum, if your'e boiling your fuel in your lines and you cant move your lines or add shields due to looks you may have to try to raise your fuels boiling point, I run 104 plus in every tank of fuel, haven't vapor locked yet. It isnt really that hot as it is sudden and humid here, your tank may have sweated and caused some separation of the water content of the fuel. I would try using additives to solve this first. There are a couple places where you can get real racing fuel around here, not that your car needs it, but racing fuel has a lot of hi temp goodies in it to keep it from detonating, I think for giggles I would run a tank of racing fuel in her, if you boil that stuff theres something more wrong.
 
Well Frank you know i add the Marvel to every tank also.. and does this make sense to you?
"Looking at the eng(which is good looking) the fuel line seems to go up hill when it comes off the firewall. If that could decline slightly on its way to the carbit might help."
 
I know you said you just filled your tank last night, so that will make it harder for you to drain your tank, but with the indented firewall, I know how nice it is to have that valve there for giving others fuel if they run out, etc...

Anyways, you can disconnect the fuel line from the carb and let it drain into a gas can when your tank gets lower, and then just unscrew your shut off valve from the tank and check for build up of junk. It is true that it could be collecting at the valve. That is just a tapered piece of metal with a small hole in it that rotates in a housing to let gas through or not. That could be a location of back up for tank junk.

Again, I like my indented firewall car when it comes to dealing with fuel issues since you don't have to deal with the pre-indented, inside the car valve stinking up the upholstery if you have to remove the shut off valve.
 
lol i just went back and checked what room i was in and it wasnt the early v/8 room, as was stated no fuel pump on the model a, so its hard for m, to believe you can have vapor lock on a gravity feed carb, maybe a partially pluged fuel line or crap in the tank, or fuel bowl filter clogged, gas cap not venting causing a vacuum in the tank, might even be an electrical problem, coil ,condensor, points, when the problem starts pull the line off at the carb to see if you have fuel flow
 
After driving across the Mojave Desert in 116 degree temps on the way to Dallas, a lot of cars in our group experienced vapor lock symptons in one way or another. Here is what I carry in my "hot tour" arsenal for those scary hot days.......

An oven door gasket that has been sliced length wise. It slips neatly over the fuel line and is held in place by some tape. I also wrap the sediment bowl in an insulated cup holder to help the fuel there stay somewhat cooler. Obviously, the idea is to try to keep the fuel from heating up.

I know that many long-time Model A owners scoff at such none-sense but, what ever I can do to prevent being on the side of the road in scorching summer heat I am open to trying.
 
I had a vapor lock problem once years ago but none since, a guy in my club uses tin foil wrapped around the fuel line to prevent it, if you try it put the shiny side out to reflect more heat.
 
The only time I ever got vapor lock on a model A is when I used a B carb, and made a line with a loop in it to fit to the different inlet place on the B carb. My fuel line had about 6 inches of horizontal area, where the fuel did not flow well under gravity. I rebent the fuel line to have a constant downward flow, and never had the problem again. I see by your photo that you have a long horizontal section near the carb. I would redo the fuel line to make it have a constant downward flow, and that will likely improve the problem, or eliminate it.
 
A recent issue of Model A News suggested adding one gallon of diesel fuel per tank to change the boiling point of the gasoline. Haven't tried it myself though.
Good Luck
 
I am of the opinion that many incidents of reported vapor lock are actually the high voltage side of the coil breaking down under heat and load. A few years ago on a trip from Los Angeles to Las Vegas I encountered temps around 110 degress. Every time I would stop for gas the temp under the hood went up and the car was hard to start and ran terrible. Once I nursed it out onto the highway and the temp under the hood came down the car ran ok. I was convinced is was due to vapor lock. Further north up in the cool mountains I did not have the problem.

It was later when the coil failed completetly that it dawned on me. I replaced the coil and have been over the same route several times in high temps and have not experience "vapor lock".
Tom Endy
 
I blame the black carb paint for absorbing heat. Two years ago in Dallas it was 100 degrees all week during the World Meet. When I got there with my 160B I drove all over the place with no vapor lock- until I took off my Marvel and put the side-bowl Zenith on. It didn't like the heat. I put the Marvel back on and drove to the speedway and back, no problems.
 
2manycars said:
The only time I ever got vapor lock on a model A is when I used a B carb, and made a line with a loop in it to fit to the different inlet place on the B carb. My fuel line had about 6 inches of horizontal area, where the fuel did not flow well under gravity. I rebent the fuel line to have a constant downward flow, and never had the problem again. I see by your photo that you have a long horizontal section near the carb. I would redo the fuel line to make it have a constant downward flow, and that will likely improve the problem, or eliminate it.
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Well you are the second to comment on the angle
of the fuel line. Let me look into that also. Tom W. Is sending some insulation also so maybe a combo of both will help.
 
Two things work for me. Cooling the fuel and increasing the fuel pressure. Both are more difficult with an indented firewall. With my 30 an insulated Coke can fastened on the fuel filter and filled with ice works as long as the ice lasts. An electric fuel pump under the dash of my 30 also works. Don't have a good method of doing them on a 31. The EPA would have hemorrhoids but someone suggested evaporation distillation. Pour the fuel in a large flat pan and let the volatile stuff evaporate. A great article about this problem with gas appeared way back in March 1986, Popular Science. No solution was offered.
 
marc hildebrant said:
Group,

Could someone explain the use of Marvel in the gas ?

Marc
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If you talking about Marvel Mysterie oi, it is pretty much just used for oiling the top end of the motor. It is mainly used for valves, since its such a thin oil it gets places that regular oil will not get to as easily. People put it in the gas since it runs through the valves. And im not so sure on this, because ive never heard of people using it for vapor lock, but my guess is because the oil is more dense than gas, it would take longer to heat up, so it has less chance to make the gas hot enough to cause problems
 
I don't think the angle would have anything to do with it as the angle would change when driving as going up a hill or down a hill. I have gotten vapor lock several times due to the E fuel
 
I have experienced a similar problem with my '31 Roadster and tried every trick in the book to stop what was a very aggravating scene. To start with, the problem is really not vapor lock since technically that can only occur when there are valves in the delivery system. Flatheads are notorious for that problem. What is occurring is that the carb has gotten hot and the fuel is boiling in the bowl causing the engine to run lean.
My resolution attempts included making 3/16 inch insulators for installation between the carb and the intake which helped but did not resolve the problem. Finally, I installed an Aries muffler and the problem went away. I then removed the insulator which was no longer needed. The first muffler had internal damage which increased the back pressure and temperatures.
 
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