Vapor Lock and how to fix it?

[Richard McBurney]

I have a 64 Deville Convertible, keep running into the same problem - vapor lock on hot days. So far I have rebuilt the carburetor , new gas tank , but when it sits in traffic on a hot day it will vapor lock .  It will take about 30 minutes for it to cool down, then starts up and runs again.  My Son said dont drive it on a hot day , think that is ridiculous.

Has anyone else run into this issue?  And does anyone know of any solutions or suggestions? 

Appreciate it 

Rick McBurney

[Kurt]

Wrapping the fuel line helped mine. With the ethanol in gasoline these days, it boils at a lower temperature than it use to. You can fine insulated tape for wrapping the fuel line at auto parts stores & elsewhere. It's not the prettiest thing in the world but it does solve the problem. It really only necessary between the fuel pump & carburetor. Air-conditioned cars have a fuel return line on the fuel filter housing which also help reduce vapor lock. Mine has that & with the wrapped line I no longer have any vapor lock problems.

Here's what I used: https://shop.advanceautoparts.com/p/design-engineering-cool-tape-1-...

Here's what it looks like installed:

[Kim K Kaiser]

I did that as well.  helped me I think.. 

I stuck some of that tape on a pot in the kitchen.  ran the gas stove on it for a set amount of time, used the temp gun to check the heat,, then ran the same pot, after it had cooled down, pulled the tape, ran the stove on it again for the same amount of time. there was a significant difference in temp on the inside of the pot from where the tape was and were it wasnt.   I also tried and wrapped the fuel pump as well, kinda archaic looking. but  I was doing all I could to keep heat off of the areas that I could.

[Anders]

You have most likely not fitted the correct gaskets below the carburetor.

However as our cars came with two different makes of carburetors you need to tell what you have. My guess though is that you have a Carter. They do have these problems if not using the correct gaskets in the correct order.

But, before you start fault finding go to "Help" (between Invite and Literature on top). Scroll down to:

Read it all and do remember the "shim" if you have a Carter. It's the shim that's most likely is missing in your setup.

[Tony and Ginny 429]

Does your engine run hotter than it should  causing higher under hood temps that may be causing  or adding to the  vapor lock issue ?

A lean running engine will run hotter than it should be 

A plug check would show plugs burning whiter than the brown paper bag color they should be 

Ethanol fuel will burn leaner than the engine  and carb were  originally designed for 

Rejetting the carb if the above applies could help reduce heat in the cylinders and under the hood 

Enjoy 

[Tony and Ginny 429]

Even if the carb was rebuilt it is still to stock specs and not recalibrated for the fuel ( ethanol ) you are now burning in the engine 

Enjoy 

[Tony and Ginny 429]

All you can do to reduce under hood temps should help your problem 

A bad clutch fan or radiator that needs replacement 

Coolant that is old and needs replacement 

Lower the temp rating of your thermostat  195 to 180 — 180 to 160 

They sell coolant additives that reduce coolant system temps by 20 degrees 

Some thoughts if you establish that the engine is running on the hot side and adding to or causing your vapor lock 

Enjoy

[Russ Austin]

Check the float level, as it could be set to low. The fuel will boil of faster with a low fuel level in the bowl.

[Tony and Ginny 429]

You can remove the rubberized shields over the A frames for the front tires to reduce engine bay heat ( if you still have them ) 

Mine are off for years and no debri from the tires has ever been a problem entering the engine bay 

Is an old Hot Rod thing to reduce engine bay heat 

Retarded timing —-will cause your engine to run hotter so check that if  the tune is over due 

Enjoy 

[Tony and Ginny 429]

For what it  is worth 

I have never had any vapor lock issues with my 64 convertibles engine and have the car off the showroom floor all these years as it was my dads car ( one of his collection of 8 - 62-64 coupes and converts all restored turn key )

I run my car often  now in 80 to 90 degree temps in Florida with the temp gauge slightly past the 1/4 mark on the temp gauge

That has me believing the problem has a solution

my 429’s performance is always a joy for me to be experiencing every time I drive the car on the very best weather days making them  a very special time 

you can help reduce the temp at the carb by removing the carb and blocking the heat passages at the front of the intake manifold  

that should reduce carb heat and vapor lock issues 

if your exhaust heat riser —-is not opening and closing Correctly that will cause the intake manifold heat passage to the carb to get much hotter than it should casing the carb to get hotter than it SB 

you can wire it open if it is not working correctly ( old Hot Rod trick ) 

Heat riser is on the driver side just below the exhaust manifold —where the exhaust pipe is connected to the manifold 

a long list of things that can be done to reduce under hood heat issues in the above posts 

my engine is completely stock with an Edelbrock carb rejetted for the fuel we now use and a point dist 

My car did not come with a clutch fan and I have had the fuel return to the gas tank disconnected for over 30 years 

hope the above helps some solve the vapor lock issue which is difficult to deal with 

[Roland Moser]

i experience something today that can be described as vapor lock.

it was a very hot day and i had to drive the car in stop and go traffic for quite some time, the idle speed began to drop and the engine was stumbeling like it was too rich or lean. i had to switch it in Park and rev it a little or the engine would stall.

the temp gauge was slightly past the 1/4 mark on the temp gauge, so the cooling system is ok.

when i was restoring the Carter i blocked the 2 holes in the manifold, see photo.

i believe the float level in the manual is to low, it says 3/8 inch to the gasket, for may understanding it should be parallel with the gasket.

your thoughts please?

[Tony and Ginny 429]

Richard 

Do all you can to reduce your under hood temps - a lot you can do 

Your temp gauge does sound like it is reading as it SB - just pass a quarter ( 1/2 is 200 degrees ) 

Running slightly advanced timing ( 8 degrees ) over the stock 5 degrees will run you engine slightly cooler and improve gas milage very slightly 

Worn points will cause retarded timing —( poor maintenance ) which will cause the engine to run hotter than normal   and reduce you gas mileage performance 

With gas expense up it pays to keep our cars well tuned and engines performing at there peak 

The ride is more enjoyable and could prevent engine vapor lock from heat build up in hot weather and having issues that stop you 

Old antifreeze will not dissipateg heat as it as it should and cause heat issues — again maintenance 

That should help some to keep you rolling 

Enjoy 

[Sammy]

Had the same issues and after testing different spacers with different materials it works fine. 
Only first start after driving when engine is hot and temperatures at 100 F it takes two or three tries 
to start it, but only 10 sec or so.