starting issue

[Poptop57]

I have a 57 Skyliner-312, electronic ignition, Edelbrock performer carb, Reds headers.  It runs fantastic but doesn't always start well. When it is warm and you shut it off, and let it set for 1/2 hour +, some times, (not always) it doesn't want to start. Crank on it forever. It acts like it is flooded with a 1 cylinder start up. Once its running, it runs fantastic. I think it is a carb issue. Any Ideas.

[oldave57]

This issue seems to come up from time to time and the consensus seems to be "vapor lock" or a similar issue caused by excessive heat build-up after the engine is stopped but the heat continues to build up.  Several have tried a phenolic spacer under the carburetor to reduce the boil-off caused by heat transfer from the intake manifold.  Others have attempted to solve the issue by adding an electric fuel pump to prime the carburetor in addition to or as a replacement for the mechanical pump. 

Does your carburetor have a phenolic spacer between the carb and intake manifold?  This might be a good place to start as well as attempting to insulate the fuel lines in close proximity to the engine block.

Below is a link to a previous thread on this issue.

http://57fordsforever.com/smf/index.php?topic=7861.msg70124#msg70124

[chapingo17]

My two cents on this, I have a 57 Fairlane 292 Y block I was having issues starting after it warmed up and sat on the parking lot for an hour. I would give it a couple of pumps to start it and it would flood (without even knowing). My theory is that carburetor gasoline (out gases) and floods intake manifold. What has work for me is to take off the air filter and start engine with no pumping gas and install filter housing back on carburetor once it turns on. While trying to eliminate hard start I also upgraded to electric pump it was vapor locking at the output of the mechanical pump. Now in days gasoline has a lot of ethanol causing this type of problems.

[81TTA]

I've had the same experience with an FE engine and Edelbrock carb.  Plus, the usual issue of longer cranking if/when the car sits for days or weeks between starts.  Thought there might be a common cause where the fuel in the bowls was leaking and/or evaporating.  So...  installed one of those generic electric in-line pumps on a manual switch so it could "fill the bowl" before starts. 

This virtually eliminted the long cranks due to the vehicle sitting "cold" for extended periods of time.  Now, a couple cranks and it fires right up.  But, it didn't do anything for the starts you describe where it's shut down "hot" and restarted tens of minutes later. 

While working on a running problem I thought was due to lean operation, I was swapping jets and rods trying to make a difference.  When the engine is up to temp, I noticed the fuel literally boiling in the bowls while I was swapping jets. 

This makes me think along the lines of the other posters.  I also believe the fuel is "vaporizing" out of the carb and into the air cleaner.  This takes a little while to take effect.  So, if you immediately re-start after shutting down, the engine fires right up without a long crank.  If you wait 15-30 minutes before restarting, all that vapor has saturated the carb/air cleaner so that, on a start, you're effectively flooding the engine.  Given enough cranking time and some luck, the engine might manage to fire up and run a little rough for a while.  But, in some cases, the engine just won't re-start when hot.  If I let it sit for longer and pretty much completely cool down, the engine would fire right up like any other "cold" start.

I don't think this is all due to the specific carb or engine.  I'd imagine this would affect any combination in the same way.  Insulating the carb from the manifold as described below would probably help. 

[KULTULZ]

It is heat soak. When you shut the engine down, the engine heats rapidly as the cooling system is no longer  functioning. The cab bowl (and fuel line) absorb heat. The fuel line increases pressure and floods the bowl. The fuel in the bowl(s) boil and either evaporate and/or flood the engine. And then you have blend separation whereas the ethanol will evaporate over time.

A carb with the fuel bowl(s) integral to the carb main body (CARTER - EDEL) will absorb more heat than will a carb design with the fuel bowls outside of the main body (HOLLEY 4150/4160 or F2100/4100). And then you have that big air cleaner that acts as a heat umbrella not letting heat escape.

If an EFI THROTTLE BODY application, it will not be the fuel bowl but as that fuel line pressurizes, the expanded fuel VOLUME has to go somewhere,

A phenolic spacer is important along with a heat shield if possible.