Dave Young

Vapor lock with our modern fuel

Recommended Posts

After spending the past few months chasing a periodic "running lean" condition with my 1928 Chandler, I finally surmised that she was experiencing vapor lock, due to the temperature of the cast iron carb.  Apparently, the new blends of fuel have a much lower boiling point than even just a few years ago.  This stuff begins to bubble at 160 degrees.  My problem arose from my fitting a different carb to the manifold, a big iron Zenith, in place of the dreadful Schebler air-valve monster that was on there.  The Zenith, being much wider, sat fairly close to the exhaust manifold drop leg.  I had fit a heat shield at the onset, but eventually, after multiple roadside "sit-and-cools-offs" , made a much larger shield and now she runs along fine.  

 

I'm wondering if anyone else out there is having trouble with carburetor, ignition and valve type symptoms and at a loss as to the cause.  My car ran great any time it was less than 60 outside.  T-shirt days she would run along for 20 minutes and then I'd be limping home as she back-puffed thru the intake and ran like crap.

Share this post


Link to post
Share on other sites

So much has been written about the ethanol problem out there and Mrspeedyt is right on. Buy ethanol free gas. It is available, more expensive, but it is available. I buy it all the time for boat motors, Corvette, mowers, Model A and T, and buy ethanol gas for the modern car and truck. 

I won't go into how I messed up the Corvette with Ethanol gas. 

If you made a metal heat shield, that may be a problem. I have talked with a few guys that have used the old style muffler wrap on their carbs. It looks like 1-inch wide asbestos tape from years ago. Works great for keeping the heat from transferring in tight spots. 

Hope you find a solution. 

Share this post


Link to post
Share on other sites

I feel that I have solved the issue by adding the heat shield.  She runs along fine now.  The shield is a two-layer metal affair with a small air gap between the layers, as would typically be done on a wood stove to reduce clearances to combustibles. I would love to find some non-ethanol fuel. Any tips as to hunting it down in New Jersey?

Share this post


Link to post
Share on other sites
Quote

Dave, when I drove my Packard in the summer months, I had the same problem. Solved it by using middle grade gas with a few oz. of Marvel Mystery Oil. I don't know if it was due to the higher octane or different volatility, but the difference was noticeable.  John 

 

Share this post


Link to post
Share on other sites

Vapor lock is not new.  It has been around from the beginning of cars.  More so on some cars than others and more or less depending on altitude you live. 

 

We are just more sensitive to it because with pressurized fuel systems with the pump in the fuel tank vapor lock can not happen on modern cars and we do not see it any more..

Share this post


Link to post
Share on other sites

Th old cure was to mount a can on the firewall and put a few coils in the fuel line and place it inside the can. Then you put ice in the can, cooling the fuel before it enters the carburetor.  There were also more elegant "cans" available on the aftermarket....

7201350.jpg

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, wilbur said:

I feel that I have solved the issue by adding the heat shield.  She runs along fine now.  The shield is a two-layer metal affair with a small air gap between the layers, as would typically be done on a wood stove to reduce clearances to combustibles. I would love to find some non-ethanol fuel. Any tips as to hunting it down in New Jersey?

It looks like New Jersey does not have many sites, but "pure-gas.com" shows 8 locations. The price/gallon is outrageous. Maybe a little more research would help. Any New Jersey members care to comment?

Best of luck in your search.

Share this post


Link to post
Share on other sites

Hey John, I need to see a picture of your Packard!  I have a wedding drive this Friday evening with the Chandler and it's going to be chilly out. All should be fine, but I do want to hunt down some straight gas somewhere.

Share this post


Link to post
Share on other sites

been getting mine at the local boat marina--some small private airports will sell it too--just get yourself a couple of 5 gal gas cans--that's my biggest problem , you can't get close to the pump,without walking---good luck --Tom

Share this post


Link to post
Share on other sites

Dave,  this is the 160 I used to own.  For me it was just too new. I am having more fun with the Special Coupe than I ever did with the Packard.  John

packard.jpg

Share this post


Link to post
Share on other sites

It also depends on when you buy the fuel.  They still used additives in the warmer months to raise the vaporization pressure and also the price.  With fuel injection becoming the norm, they may stop doing it or at least reduce the amount of additives.

Share this post


Link to post
Share on other sites

We are having a huge problem here in California with the ethanol gas and carburated cars. Palm Springs hits the triple digits pretty often and I was having a similar vapor lock type issue. Especially after a 10 or 15 minute shut off and heat soak. I decided to wrap the steel fuel line from the fuel pump to the carb with Thermo-Tec, also covered the top portion of the fuel pump with it. I think I might be OK now, just have to wait for those triple digits again to be certain.

Share this post


Link to post
Share on other sites

There was much discussion on this topic earlier this year. One cure is to add from 10% to 25% kerosene or stove oil to the gas. The percentage depends on the compression ratio. Your Chandler should take the full 25%. Everyone knows not to use gas of too low octane but it is a mistake to use too high octane. Your car was made when gas was low in octane and contained a lot of heavy ends or oily elements like kerosene. One Australian cured a similar problem by adding diesel fuel. This is heavier than kerosene or stove oil but it worked, the car did not smoke, but there was a slight diesel smell at idle from the exhaust.

 

Owners of 20s cars report that their car runs better, smoother, cooler, and develops more power on the mixed fuel.

  • Like 1

Share this post


Link to post
Share on other sites

Adding Kerosene is certainly beneficial but its a common misconception that the increased volatility of modern fuels is related to octane rating, refer to the attached article by BP on the subject (Petrol =Gas)  

 

modern-petrol-vintage-engines.pdf

Share this post


Link to post
Share on other sites

I would add the muffler wrap to the heat shield. But only put the wrap on the carb side of the shield. With the air gap and the wrap you are providing a double protection barrier. 

Share this post


Link to post
Share on other sites

Correct, the octane rating has nothing to do with vapor lock. It's what's added to the gas, such as ethanol, which has a much lower boiling point than gasoline.

 

Around here many stations have switched to e-free 91 octane . It matters not that it's high test, what matters is that there's no ethanol in the high test and that is what benefits cars prone to vapor lock.

 

One other common cause of vapor lock is lugging the motor, and not downshifting sooner to get the rpms up.  Lugging the motor makes it generate more heat while at the same time making the cooling system go slower.

 

Paul

Share this post


Link to post
Share on other sites

I've been very lucky to have good access to No-Ethanol gas locally, but my PureGas App does help when travelling. Here we generally pay $2.29 for pure 87 octane when normal gas is around $2/gal. Driving the '88 'Vette to central Florida last month for a Region Tour, we paid as much as $4/gal for No-Ethanol in the Florida Panhandle, and $3/gal in the Orlando area at Wa-Wa Stations.

 

When I cannot get No-Ethanol gas during a Tour, I use the LOWEST OCTANE AVAILABLE, and ADD 10%-15% DIESEL - readily available !

This will cause your engine to smoke, and to give the appearance of "burning oil", because it really is the case, but don't believe your friends who tell you that your rings are worn out - it is only the Diesel mixture,.

 

We did this during the 2015 Glidden Tour in Oklahoma city with temps in the 100 - 115 range while driving the 1941 Cadillac which is extremely prone to vapor lock, and never experienced the issue at all (while many others succumbed to the dreaded vapor lock).

 

Other things we did to the Caddy were to fashion a heat shield to protect the carburetor from the exhaust crossover pipe immediately behind it, and to install a COOL-CARB gasket which is two aluminum plates with a sandwiched poly-core to minimize heat transfer from the intake manifold.

  • Like 1

Share this post


Link to post
Share on other sites

Marty,

              I'm surprised to hear you had any issues with the ethanol gas in your '88 Corvette? Our gas here in California is terrible on all my carburated vehicles but I don't experience any trouble with my injected cars.

Greg

Share this post


Link to post
Share on other sites
27 minutes ago, GregLaR said:

... Our gas here in California is terrible on all my carburated vehicles...

 

I've heard that gas must be different out West, 

so maybe other urban areas have similarly bad compositions

that contribute to the problem--more than just ethanol.

 

A friend in Washington state, said his gas would go bad

in only 6 weeks.

 

Another person, from California, agreed.  He told us in a

newsletter interview in 2013, "Modern gas, especially in California,

is so bad, that in some of my steam cars, if I don't go out

or the car hasn't been moved in a month or so, I've got to

drain the gas out because it literally won't fire.  You put a 

match to it and it will burn like oil."  He said he was using

a Sta-bil product, filling the tank right to the top, and 

typing to get the best-sealing gas-cap possible to try to

keep the fuel from going bad.  I assume he solved the

problem more or less, because he had had one steam

car up to 75 m.p.h. on the open road.

 

So car fans in Kansas or Pennsylvania or other states

might not have all the answers needed--but let's hope 

poster Wilbur has his Chandler's fuel problems solved now!

 

Share this post


Link to post
Share on other sites
1 hour ago, GregLaR said:

Marty,

              I'm surprised to hear you had any issues with the ethanol gas in your '88 Corvette? Our gas here in California is terrible on all my carburated vehicles but I don't experience any trouble with my injected cars.

Greg

 

Greg, the Corvette didn't show any problems, but I prefer not to use Ethanol, knowing the damage and rust issues which will ensue if left in the system. Our 1988 BMW 528e had Ethanol left in the system for a moderately extended time, destroying the tank, pump, steel lines and all six injectors - and you don't want to know the cost of parts and labor to replace all of that stuff, especially at BMW prices. Ethanol fuel allows water vapor to condense into the fuel and to precipitate the rust issues - think $,$$$.$$

(enjoyed your Kaiser last spring)

  • Sad 1

Share this post


Link to post
Share on other sites

On the 1929 Franklin I drive the most I add 2-3 gals of diesel to a full tank of gas and it corrects the problem, It lowers the flash point of the fuel. The car performs just fine and no more vapor lock ... Try it. Ive also used a inline electric pump that I use only for starting after the car has sat a long time (eliminates the need to crank a long time to get gas to the carb.) and when the car hiccups from vapor lock , I flip the pump on for a few seconds and it clears out the line. Im sure the heat shields help and its a good idea.

Share this post


Link to post
Share on other sites

It is another common misconception that vapor lock is caused only by the ethanol added to the fuel.  There is no doubt that ethanol increases the problem,  here in Australia  we have the option of fuels with 10% ethanol and we avoid it it in our old cars. however in hot weather, vapor lock can occur even when running with non ethanol fuels .

 

Vapor lock has been an issue from the days of early motoring , consider this opening paragraph from a letter from the Packard Motor Company dated July 31 1931 addressed to its dealers and distributors  Quote:

 

'"Technical Letter 1895 dated March 17 1930 reviewed the gasoline situation and outlined the steps which had been taken to prevent the development of vapor lock in the fuel lines and the carburetor.  ...................."  The letter goes on to describe further changes recommended to avoid the vapor lock.   Incidentally those changes may well have worked in 1931 but with increasingly volatile fuels  they are not entirely effective now. 

 

The solution is to lower the temperature of the gas in the carburetor however that can be easier said than done.

 

.

 

 

 

 

 

 

 

 

 

 

 

 

 

Share this post


Link to post
Share on other sites

A few years ago, Skinned Knuckles magazine stated that the boiling point of 10% ethanol at 3-5 psi was 182*F underhood temperature at or near sea level.  Today's gasoline is formulated for EFI engines with fuel pressure of more than 35 psi, sometimes substantially more.

 

For those of us with updraft carbs especially those fed by gravity from vacuum tanks, it's even worse:  They had problems with gasoline being not volatile enough in winter, hence exhaust downpipes at the front of the engine where the fan would blow heated exhaust air at the carbs, and the variety of hot-spot manifoldings.  No summer/winter blends then.

 

In 1943 or so, Cadillac changed the design of their fuel pumps for 1937-forward V8s due to vapor lock issues.  Those engines' manifolds are on top of the heads and today must usually be shielded.

As mentioned, we need to reduce the temperature of the fuel in the engine compartment by shielding fuel lines and/or carbs from sources of heat.

Share this post


Link to post
Share on other sites

Shielding is good for reducing radiant heat transmission  however  it does nothing to prevent the convective heat transfer from the hot engine bay and this might be the greater cause of the problem.  I have experimented with a heat shield that  fully encapsulated the vacuum tank and it seemed to make the problem worse and I suspect this was because the shield was  actually retaining heat.  There are no easy solutions, In hot weather I carry a water bottle and rag to wet the vacuum tank and carburetor which gives instant cure but not for very long.  On a very hot day here it can be a PITA.

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now