Fuel System: Vapor Lock

[Speedster#201]

neoprene impregnated fabric fuel lines, inline fuel cooler, and a heat shield around the engine mounted fuel pump.

The most difficult fix for me will be the heat shield and I wanted to ask if anyone has heard of such an item for purchase that will fit a 259 V8 on a Speedster.

Leads, advice, etc. on vapor lock in general and a heat shield in particular would be most appreciated.

Thanks.

[jg61hawk]

Only recently did my 61 Hawk Vapor Lock. I did some research and I believe the following is what I'm going do:

Use LOWEST Octane fuel that will not ping (if you have to use Ethanol fuel...something to do with Butane not really the ethanol..plus the higher the octane the hotter it burns).

I'm putting a third more Marvel Mystery Oil in the gas than they recoomend (12 ounces to a tank as opposed to 8).

I wrapped my fuel line with wire and let the end of the wire hang down off the line acting like a heat sink.

Obviously keep the fuel line routed as far as possible away from the exhaust manifold.

I know the Marvel Mystery Oil comment will have some saying I'm crazy but it does make sense that adding that will slow the evaporation process.

[Michidan]

So far this year I have had no more vapor lock problems. I did several things but the biggest help I think was a 1" phenolic carb spacer. (You can even make one out wood if you need to). Second biggest help was a 7 blade steel fan that replaced the stupid flex-fan I had. I also installed an electric fuel pump back by the tank as a helper. This was by far the most work, and I have yet to even use it.

[Tom Bredehoft]

the higher the octane the hotter it burns

I believe this is an old wives tale. Fact are, the higher the octane, the lower the ignition point. Thats wrong, the higher the octane, the higher the igntion temp. Thats' why it helps when the engine pings.

The best cure I've found for Vapor Lock, is a return fuel line, the pump keeps pressure on the line, if it is allowed to return to the tank, it doesn't collect heat, doesn't get to the vapor point, as easily. You do need a restriction so only a little returns to the tanks, put a Y in the line just before it reaches the carb, with an .040 restriction in the return line will improve your vapor lock problem.

[JoeHall]

Do a search in the archives here, and you will find lots of discussion on vapor lock and how to alleviate it. You can also poke around the web and read about vapor lock in most other makes and models of the 1970s-early 80s, i.e. motor homes, sports cars, pickup trucks, luxury cars, etc. You will find similarity in many factory and individual's attempts to fix it; there really isn't much that has not been tried. There is nothing new under the sun, when it comes to Stude drivers' attempted remedies either, i.e. Ford used a return line in the 1970s, as was suggested above. There's also a Studebaker Tech Bulletin from 1957, advising how to deal with it on supercharged cars way back then.

Basically you will find there are several ways to reduce vapor lock severity. Collectively, all methods tried to date will minimize the symptoms, but will not CURE it. The only actual cure is EFI, which most Stude folks cannot justify the expense of.

[jackb]

and also back to basics: what temperature is the engine actually running ? If you're at or around 200 degrees, you're probably in trouble without the above aids..

[raprice]

There's an old mechanic's cure for vapor lock. It involves putting wooden clothes pins on the fuel line under the hood. It works.
Rog

[altair]

There are a lot of theories about vapor locks, but a frozen hear riser in the closed position can be a major factor combined with a small pin hole in the fuel line. The fuel line is operating under vacuum and air mixed with the fuel can also be a contributing factor. Many of the early cars ran at a relatively low temperature whereas some later cars ran with an elevated temperatrure to meet the enviornmental standards and to avoid vapor lock problems the intake manifolds were liquid cooled (soon after fuel injected) A sound cooling system, fuel system, ie no vacuum leaks and a proper working heat riser control system will eliminate most vapor lock issues. Gasoline boils about 175 degrees F., fuel management under that temperature will eliminate vapor locking. Dave

[aftontrix]

You guys make me nervous. I have been driving my 57 Silver Hawk with a 1958 289 engine here in southern Oklahoma for the past four years. It gets over 100 degrees here in the summer and I take it out even though no A/C. I feel like I am driving in a steam bath but it has never vapor locked. I have a mechanical fuel pump and a two barrel carb. I use 100 percent gas, no alcohol. Now I am starting to worry that it may vapor lock someday. What do you do to get it started if it does happen? Thanks

[JoeHall]

You guys make me nervous. I have been driving my 57 Silver Hawk with a 1958 289 engine here in southern Oklahoma for the past four years. It gets over 100 degrees here in the summer and I take it out even though no A/C. I feel like I am driving in a steam bath but it has never vapor locked. I have a mechanical fuel pump and a two barrel carb. I use 100 percent gas, no alcohol. Now I am starting to worry that it may vapor lock someday. What do you do to get it started if it does happen? Thanks

Just put some clothespins on the line, and a rabbit's foot on the key chain, and you'll be good to go for at least another four years

[jackb]

again......when I lived in Central Texas, my 64' ragtop would vapor lock at temps above 100 degrees. Old Studebaker dealer advised wooden clothespin solution: no further problems.... or on another humorous note...I remember at an International Meet many years ago, a fellow in a bullet-nosed car cured his vapor lock by placing cold grapefruits cut in half over his fuel pump on the side of the road for a quick, albeit, temporary fix.......just FWIW... I like late night driving in hot weather when travelling long distances.....

[dougsoldcars]

I've heard the clothes pin really works, but I have a couple of other suggestions as I just sorted this out on my wife's Avanti which would get vapor lock during the summer here in florida which is fairly hot. I put on an Airtex electric fuel pump that I can switch on and off. I also add sea foam if I have to buy gas with ethanol. The best deal is that down here they sell RV fuel that has no ethanol. I just add 108 octane boost to keep the octane rating up. Hope this helps.
Doug

[Flashback]

An electric fuel pump helps. Rerouting fuel line helps. No ethanol gas helps-a lot. phelonic spacer helps. An aluminum intake helps. Blocking the heat passage to intake helps. I don't have room for a spacer on my car, but I did all the other items I mentioned above My fuel line comes in at the back of the fender well. You can see it crossing over on the firewall. The one other thing I did was install the cool can you see. Its a emergency measure.

I deleted the heat riser (damper) from the exhaust. I also DO NOT use ethanol gas, and I mix my gas with avation fuel.

These items all help, but lets assume from the beginning you don't have a overheating problem

[SScopelli]

I believe this is an old wives tale. Fact are, the higher the octane, the lower the ignition point.

The best cure I've found for Vapor Lock, is a return fuel line, the pump keeps pressure on the line, if it is allowed to return to the tank, it doesn't collect heat, doesn't get to the vapor point, as easily. You do need a restriction so only a little returns to the tanks, put a Y in the line just before it reaches the carb, with an .040 restriction in the return line will improve your vapor lock problem.

Return line is optimal in the vapor lock solution.

I'm ready for the comments..

But you need to get the heat off the top of the engine and carburetor! This is no longer 1940!

This involves removing your intake and blocking off the exhaust crossover on the intake and taking out that flapper valve!

Blocking the crossover, the temp drop on the manifold is PHENOMENAL!

Also, install a thick phenolic spacer between the intake and carb. Vapor Lock is not only in the fuel lines, but the bowl of the carburetor!

You can see the R1 fuel filter with return line in my picture below.



Sorry for the old blurry picture..

You can buy this Fram G3499 version from 70's cars at any auto parts store.




Running the return line back to the tank is real easy with a coil of 1/4 tubing. What gets tricky is soldering in the return line pipe in the tank!

BTW, I'd skip the thermal tape.. Once the heat soaks through the thermal tape it will hold the heat longer when it is not running!

87 Octane, Mechanical R1 pump, in Phoenix at 118, no vapor lock..

[JoeHall]

Return line is optimal in the vapor lock solution.

I'm ready for the comments..

But you need to get the heat off the top of the engine and carburetor! This is no longer 1940!

This involves removing your intake and blocking off the exhaust crossover on the intake and taking out that flapper valve!

Blocking the crossover, the temp drop on the manifold is PHENOMENAL!

Also, install a thick phenolic spacer between the intake and carb. Vapor Lock is not only in the fuel lines, but the bowl of the carburetor!

You can see the R1 fuel filter with return line in my picture below.



Sorry for the old blurry picture..

You can buy this Fram G3499 version from 70's cars at any auto parts store.




Running the return line back to the tank is real easy with a coil of 1/4 tubing. What gets tricky is soldering in the return line pipe in the tank!

BTW, I'd skip the thermal tape.. Once the heat soaks through the thermal tape it will hold the heat longer when it is not running!

87 Octane, Mechanical R1 pump, in Phoenix at 118, no vapor lock..

I agree a return line helps a lot. While the motor is running, it keeps the fuel flowing fast enough that it stays cooler. Also in hot restarts, if you give it a few seconds with the electric pump on before cranking the motor, it will purge the line with fresh, cool fuel. The fuel in the carb bowl, and in the line coming into the carb though, is still prone to vaporizing, especially during hot restarts, but clears up a lot quicker with fresh fuel coming up to the return junction.

As for clothes pins, that idea reminds me of high school days and working in the hay fields of Kentucky during the hot summers. Most of the old hay trucks were flat sixes, and most of them vapor locked. Raising the hood, you'd find clothes pins everywhere, but they still vapor locked. When we'd stop for lunch about a half hour in the heat of the day, we'd all hope the truck would not restart, and about half the time it wouldn't. Only more time, water, urine, or whatever else handy on the fuel pump would eventually help it restart, IF the battery didn't run down first. If clothes pins were a cure all, I'd have probably made more money, because I got paid by the bale (about 3 cents each), not by the hour