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

[msmaron]

Well had vapor lock this AM... Hot here in Chicago and very frustrating,. What is the best way to help prevent that from happening and why is it happening., What adjustments need to be made
mark

[ford1]

keep all the fuel lines as far away from the exhaust system as you can, when the lines are close to the exhaust system shield them with metal shields, create an air space between the exhaust and the lines, do the same with the fuel pump, some speed shops sell a shield that bolts on the engine between the pump and block if not make one

[msmaron]

There is NO FUEL PUMP???? and the lines cannot be moved away from where they are. This is a 31 sidebowl carb...I can see keeping away from heat but there has to be other ways?

[Logan]

make sure you have a good venting cap. then also this is not original but run a rubber gas line instead of a metal one. We cut ours about 3 inches from the sediment bowl or in your case the shut of valve. Then do the same thing on the line that attaches to the carb. It keeps the gas cooler, and as we all know mostlikely the rubber line will not get as hot as the metal one. Also Tillison carbs dont get as hot as the zeniths because of the different kind of metals. Hope this helps.

[Logan]

also if it happens again, pour soda (yes the drink) on the carb.

[Mitch//pa]

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are your engine pans installed?

[msmaron]

Logan, sent you an email, please explain as in the email
Mark

[Jason in TX]

Logan has some good advise. He's saying to cut your metal fuel line and use hose clamps to clamp rubber line onto the short piece of metal fuel line left that is coming out of the shut off valve. You could also use a hose barb on a late 31 with shut off valve outside the car.

Or you can try the old trick of wooden clothes pins clipped on the fuel line to pull the heat away from the fuel lines. I think that trick is a little bit of snake oil though.

If you are wanting to keep the metal lines for when people look at your car, but have something you can put on when you're driving, why not try cutting a piece of rubber fuel line length ways so that you can slip it over your metal fuel line like a piece of foam insulation on a pipe. Then just pull it off at a show. I have no experience with something like that, but it might work also.

[msmaron]

That is what i was thinking, like an insulator rather than replace. I have never had this happen with my other car, so i was a bit concerned..

[Jason in TX]

the rubber fuel line won't go around corners very easily after you cut a big slit in it, so you will probably need to hodge podge put a few pieces on there. Or secure it with hose clamps or zip ties

[msmaron]

MMO i add 4 oz to EVERY single fill up and last night did the same when i filled it up and boom in the am, VAPOR LOCK!

[Jason in TX]

Your car should be pretty cool in the AM. This isn't hot mid-day driving you're talking about.

Could it possibly be sediment from your tank collecting at the fuel shut off valve? Do you have one of those tiny fuel filter screens behind your shut off valve?

[msmaron]

Yes there is a filter, i have an indented fire wall with the shut off outside the car.,

[Jason in TX]

Oh yeah. I forgot you had the indented firewall. That opening for the fuel shut of valve shouldn't have any junk in it. The side bowl on the carb shouldn't clog since the sediment should just fall to the bottom of the bowl of the filter.

So yup. I would say vapor lock as well. I guess give the insulation trick a try.

[Jason in TX]

By the way, that is a beautiful stock looking engine compartment. It would be a shame to start sticking all kinds of silly looking stuff all over that fuel line!

[msmaron]

I know that is what is making me crazy to go ahead and start adding tubing and tape and such.. Has to be another way to prevent this

[Blessyouboys]

Are you certain your fuel tank is vented through the cap properly?

I've been been driving my Tudor all day in this heat, and I have had absolutely no problems with it. I've also never had a problem with the 10% ethanol we have to deal with here.

[msmaron]

yes i have a vented gas cap,. Would a bad one make a difference?

[roccaas]

A poorly venting cap (clogged) will allow vacuum to build up in the tank and the gas won't easily flow. I had an old Z car that vapor locked (SU carbs next to the exhaust manifold), such that we had to put on Webers. It also had a vacuum cleaner strong cap that had to be manually vented as the fuel level dropped by more than 1/4th of the tank.

I run straight gas with no booze in it, so I cannot comment on the ethanol issue.

[msmaron]

Originally Posted by roccaas

A poorly venting cap (clogged) will allow vacuum to build up in the tank and the gas won't easily flow.

Well let me check it out and thank you

[Mountain Dew]

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.

[cradlescyth]

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!!

[msmaron]

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.,

[Frank The Plumber]

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.

[msmaron]

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."

[Jason in TX]

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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.

[ford1]

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

[oldman - NorCal]

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.

[1stWoody]

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.

[2manycars]

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.

[Steve Miller]

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

[Tom Endy]

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

[MikeK]

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.

[msmaron]

Originally Posted by 2manycars

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.

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.

[Jerry Parr WI]

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]

Group,

Could someone explain the use of Marvel in the gas ?

Marc

[Special Coupe Frank]

Mark,

How hot was it out there today ?

[Logan]

Originally Posted by marc hildebrant

Group,

Could someone explain the use of Marvel in the gas ?

Marc

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

[Model A Man]

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

[Aerocraft]

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.

[anut]

this is all new to me i have had stock model/s for 65 years and this is first time i have heard of vapor lock no sush thing check for other causes

[MikeK]

Originally Posted by Logan

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

When all else fails, I ask my wife (Ph.D., knows lots of organic chem). HER answer:
The reduction in vapor lock effect seen by compositional changes to fuel (the addition of MMO, kerosene, diesel fuel, or anything else to the gasoline) is basically the result of changes in the interactions of azeotropes within the zeotropic mixture we call gasoline. That zeotrope varies widely by region, brand, grade, and seasonal blend. Deviations from Raoult’s law (vapor pressure of solutions) result from the addition of anything to the complex gasoline mix. Anything that will effect a negative azeotropic relationship with the fuel components having the highest vaporization potential will reduce the vapor lock effect. The opposite is also true, some additives may initiate positive azeotropes. Basically, vapor lock is the start of fractional distillation, and you want to change that paradigm.

I'd ask what the hell her answer means, but I know better!
So, instead, I asked her what she would do if suddenly stuck on the road with vapor lock.
Her answer: That's a dumbass question, pickup my cell and CALL YOU.
Suggestion: Try a different brand/ grade, some have way too much butane for cars without pressurized fuel systems. Make sure there are no pressure drop points (restrictions) or vaporization initiators (scratches, rust, dirt) in the fuel system. Oh yeah, and that clothespin on the fuel line thing you asked about? They absorb resonance harmonics that serve as an energy source to initiate vaporization in the fuel line. And mow the grass.

I'm not sure mowing the grass would help, but if it was my vapor lock problem, I'd do it anyway. Always remember, the wife is never wrong. Fortunately, I don't have a vapor lock problem, so no need to mow today.

[Tacoma Bob]

I wish i knew how to post a picture. BUT! (and all will laugh) I have no vapor lock issues but I did and experiment. I took a foam beer can cooler and cut a couple of notches and slipped up the sediment bowl. the notches were to clear the fuel lines. I made a simple bail handle to secure the unit to the bowl. On a tour with several other A's I took temperature readings throughout the day with a thermal gun on the metal top of the bowl. Mine was 20 degrees cooler than all the other cars.

[modelAtony]

only way completely for me is adding a 6 volt fuel pump.

[msmaron]

Originally Posted by MikeK

When all else fails, I ask my wife (Ph.D., knows lots of organic chem). HER answer:
The reduction in vapor lock effect seen by compositional changes to fuel (the addition of MMO, kerosene, diesel fuel, or anything else to the gasoline) is basically the result of changes in the interactions of azeotropes within the zeotropic mixture we call gasoline. That zeotrope varies widely by region, brand, grade, and seasonal blend. Deviations from Raoult’s law (vapor pressure of solutions) result from the addition of anything to the complex gasoline mix. Anything that will effect a negative azeotropic relationship with the fuel components having the highest vaporization potential will reduce the vapor lock effect. The opposite is also true, some additives may initiate positive azeotropes. Basically, vapor lock is the start of fractional distillation, and you want to change that paradigm.

MIKE...WTF!!! just what Henry would say... NOW here is an interesting FACT... When i used Phillips GASOLINE i had the problem... When i used MOBIL i did not, I asked the Phillips manager about his gas. He told me" We buy it everyday from the cheapest person we can find, we have to compete with the big boys and no one knows anyway"...Now we might be getting somewhere?
So....my thoughts are...change gas brand, and insulate the fuel line.. Take both steps first and then remove the insulation with the better gas and see what happens.

Thanks MIKE and Thanks to your wife....i think??hahahaha
PS when are we going to see you at a meeting.. Are you going to French Lick?