Fuel boil off

[twodko]

Our 69 has an Edlebrock Performer series 750cfm carb sitting atop a phenolic plate over a stock manifold. The OO put the phenolic plate in an attempt to isolate the carb from too much heat. Motor is stock otherwise - no headers. The issue is when the mill is up to operating temps and gets shut off its a bitch to get the car started again. I asked the OO about this and he says this happens because the gas gets boiled off, so theres no juice in the bowls and I have to pump hell out of it while cranking it over until it finally starts. Is this what's happening? What would be the remedy? Is this common. Thanks gang!

Tom

[Piston_Freddy]

Is the exhaust crossover blocked?

[Ghoste]

It is what's happening and the Carter style carbs are a little notorious for it with modern fuels.  Isolating the fuel system from the heat is about all you can do.  Run the starter for a short bit to fill the bowls or get a small electric pump as a helper to get fuel up there are a couple of things you can do.

[daveco]

Very common: "Vapor Lock"
Do you have a return line & vapor separator style fuel filter?

[68X426]

Tom, maybe even wrap some heat shield material around the incoming lines where they are close to the intake and block.

I feel you pain.

[twodko]

Hey Fellas,

Thanks for your input, boil off was what I thought but I needed your validation. As usual you guys are the best!

[FLG]

Did you block off the heat crossover? That sure warms things up.

[bobs66440]

Did you block off the heat crossover? That sure warms things up.

I blocked mine recently because of the same problem. I haven't had much of a chance to test it but soon I hope.

[twodko]

I have skills but engines.........not so much (but I'm learning). Educate me on the "heat crossover" thingy. Is this the valve between the exhaust manifold and the exhaust pipe that stays closed until the engine is up to temp?
Man, its embarrassing telling you guys I don't know much about these things. Humbling.

[FLG]

Theres a little hole in the center of the intake ports and center of the heads (right under the half moon shape) which allows hot exhaust to flow up and into the intake to keep it warm in the winter but with the gas the way it is now it really causes issues more than anything.  Felpro makes a valley pan gasket that blocks off this port.

[Brock Samson]

   This topic has been covered before a couple of times...
   Search "Vapor Lock".
The old mechanics i knew back when i had the issue with my souped up 318, told me to put a clothes pin on the fuel line, it worked most of the time because i think the metal spring on the wood would help dissipate the heat faster, it didn't seem to cure the problem but it did seem to help, and when i would go to car shows back then the old-timers would mention it and ask if i got vapor lock.   

[bobs66440]

  This topic has been covered before a couple of times...
  Search "Vapor Lock".
The old mechanics i knew back when i had the issue with my souped up 318, told me to put a clothes pin on the fuel line, it worked most of the time because i think the metal spring on the wood would help dissipate the heat faster, it didn't seem to cure the problem but it did seem to help, and when i would go to car shows back then the old-timers would mention it and ask if i got vapor lock.  

Interesting idea. If you want to be really cool use a finned aluminum clothes pin!   There's probably hundreds of those old-timer fixes that work great but will be lost to time because they sound funny and people won't try it.