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?
Not sure where the intake can and might crack myself
When you tighten down the bolts work from the center bolts to both ends of the intake
Make all bolts just snug first then going around and around tightening them down a little at a time until you are ready to use a torque wrench for the last turns on the bolts to seat the manifold —evenly
Not at all sure about using the brake cleaner spray —-as I always use water which I know is not a problem to be running thru an engine and does not stall the engine just changes its sound
Water will remove carbon deposits in an engine so it is ok to be using
Best I can do regarding installation advice
As you have had a problem with one side of the manifold or the other not seating correctly - could you have the wrong intake manifold on your year engine ?
There are two different 390 engines
The 62 and 63 are different engine designs but not sure if the intake is the same one
I only ask that - as these car engines have often gone thru a number of parts changes thru the years in many cases with hobby mechanics who do the best they can to get the correct replacement part
Just a long shot thought —that comes to mind under the circumstances you have described with one side not seating correctly —twice
Found receipts and history what I did 8 years ago when I installed the 1406 to keep heat from carburetor and fuel.
Tried different spacers like Mr Gasket 6006, Edelbrock 8711.
Either they didn't fit perfect or it was still hard to start the engine when it already ran hot before.
Best solution I found was insulator 8723 from Edelbrock.
No stall anymore, only takes a little time (some seconds) to get it started when engine is hot.
But beside that no issues.
With the correct insulations for this spacer (I can't find the number anymore for the insulations) I did not need to fill the holes in the original intake manifold.
And I didn't use original spacer at all, PCV directly into carburetor.
The small tube going into the original choke I just plugged with a carb grommet and used the
electric choke from Edelbrock.
And height is still ok with original air filter housing, too.
Just to keep it as original as possible.
Maybe this helps a little.
Thank you Sammy
Your spark plugs and some cylinders ( closest to the air leak ) SB burning lean ( and hot ) if you have an air leak ( vacuum leak ) from outside air into the intake manifold anyplace
Plugs will have a whiteish color - S B the color of brown paper bag when correct
Use a spray bottle with water and spray all the intake seems and the carb base
You will hear the engine change its sound when you find the air leak spot for a moment
i don't know about an electric or manual choke conversion...
the car was running fine before i had this vacuum leak on the intake manifold.
is someone using the FelPro metal gasket with success?
Thats all I have been using,
just removed the intake manifold.
i can't see a crack from the undersite where it sucked air, but on all 4 intake ports on the passenger side you can see that the gasket is wet and did not stick on the lower part of the ports.
i was using the Best Gasket, will give the FelPro a try now.
would you use Gasket sealer around the ports?
Looks like you found your problem with the intake manifold vac air leak — wonderful !
The new gaskets SB just fine without additional sealant
I only use it to be holding a gasket in place when needed as it makes for easy removal if needed in the future
Russ’s expertise and advice on this site is about as good it gets about our year Cadillacs
Spray your intake manifold seams and the carb to intake seams with a spray bottle of water to find the location of your air leak
The sound of the engine will change— when you spray water on the air leak location- at an idle
Knowing the location of the intake air leak— should help to focus on that location to correct and seal it