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

[Roland Moser]

replaced the Fuel pump today with a new Carter M3993, the fuel filter glass still holds not more fuel than before, engine still stalls if its hot and long enough idling.

BUT! i sprayed some brake cleaner along the intake manifold to the cylinder heads, guess what! the engine reacts to this and mostly stalls. seems like the engine gets wrong air, i changed the intake gaskets with new ones from Best (14046E) 4 years ago when i was rebuilding the carb and i never thougt that there is such a problem now.

will remove the intake manifold and see if its cracked underneath.

what intake gaskets do you prefer?

the ones from FelPro are metal, is that a tight sealing? 

[Kurt]

I had the FelRo metal gaskets on my intake a few years ago and the car developed a stalling problem when hot and would make a high pitched whistling sound. That turned out to be a vacuum leak between the intake and head. The whistling was the metal gasket vibrating like when you blow on a blade of grass between your thumbs. When I replaced the intake gasket, I decided to block off the exhaust running through the intake as the heat is excessive. I would literally hear the gas boiling in the carb after long drives. I used the Best gasket because they are thicker and that solved my problem. If your car is non-AC and without the vapor return line to the gas tank, your fuel level in the filter bowl may be normal. From your latest info, it sounds like you have a vacuum leak and that  may be your stalling problem

[Roland Moser]

yes, it really seems the main problem is a vacuum leak between the carb and cylinder heads.

i'll give the FelPro a try, Rockauto has only the metal gaskets.

[Mack]

Don’t waste your time with that. 
call Olson Gaskets 360.871.1207 and order intake gasket with pre heat (middle) port blocked for the intake manifold. At the same time get rid off the heat riser on the drivers side exhaust manifold… their gasket is thick and blocks the exhaust going under the carb that makes it hot, you don’t need that anymore. all the standard gaskets are steal so they transfer heat from heads up to the intake and the  intake onto carburetor… stupid. Like I said in me earlier posting, I thought that for a few years now. 

All you need to do is take the internal temp under the hood down which causes the vapor lock. 

ohhhhh and yes, make sure you don’t run too lean so adjust the carb as well.

[Roland Moser]

the heat riser is already removed from my exhaust job couple years ago.

how does the hot air choke work when i block the middle ports?

[Mack]

What carb you got???

choke will open up regardless due to the temp OR just get yourself an electric choke which is 5min install and works just fine.

[Kurt]

I installed a manual choke cable on mine. I like that I can fully control the choke at all times and now no seasonal adjustments are necessary. 

[Tony and Ginny 429]

Kurt 

As you stated the Edelbrock electric choke does work better than the stock choke ( which I really dislike ) but not perfect by any means requiring some  adjustment based on the current outside temp from season to season 

The Manual choke —is the only fool proof best working choke for those reasons 

As I only use my car sometimes 

I remove my air cleaner and set my choke by hand ( open 1/8 inch at start up ) and prime the carb ( due to car sitting for periods of time ) and I get an instant fire up that saves my starter and battery —-from nasty abuse 

The carb heats quickly once running and opens the choke butterfly  fully with no other issues until I do the same procedure  next time I use the car 

Has been my best solution and easy enough to do - -instant fire up 

Baroooooooooom ! 
Enjoy 

[Tony and Ginny 429]

You can wire —-the heat riser open if you still have one 

An old hot rod trick 

Enjoy 

[Roland Moser]

you were right!

installed the manifold with the thin metal Felpro Gaskets (MS8931SH1) and guess what?

still sucks air!

absolute waste of time!

[Tony and Ginny 429]

 Richard

Could you have a crack in your intake that you are not possibly  aware of ? 

Cracks in  the intake manifold  (  air leaks    ) have been  somewhat common on our year Cadillacs from time to time 

As Russ says —- he  always uses the Fel Pro gasket I am sure the gasket material is not your issue at all 

I would review your gasket installation procedure

Enjoy  

[Roland Moser]

there is no crack in the manifold, i inspected it thoroughly when removed.

where exactly do they crack?

when i spray brake cleaner between the manifold and cylinder heads the engine runs rough or even stalls, now its the drivers side gasket, before the new FelPro gaskets it was the passenger side.