Verifying heat soak.

[-009-]

Do the below symptoms sound correct for a heat soak issue? The car has a 340 with a mechanical fuel pump and an Edelbrock AVS2 carb. The fuel lines are routed in the stock location.

A quick rundown of starting issues.
- After sitting overnight it will take multiple attempts to start. A few attempts later it will sputter and eventually start.
- Once it's been running for a while you can shut the car off and immediately restart it with the flick of a key. (the carb gets hot to the touch)
- A couple of minutes of sitting later it will no longer start until after three or four attempts.

It looks like the correct spacer will be the #8711.

Thanks for the help. Though after writing this post it seems like that is the issue.
Want to be sure before I toss more money at this car.

[Cuda Cody]

Before you start the car, can you pump the gas pedal and have someone watch the carb and see if fuel is being dispensed from the fuel bowl down the barrel into the intake?  Basically, when you hit the gas do you see a stream of fuel coming out of the jets?

[1 Wild R/T]

Yes.. When you try to start it cold the carb is dry cause the fuel boiled out the night before...  If you crank it & get it to start but then shut it off before theres any heat in the engine it should start pretty easy the next day....  When you shut it off hot & try to restart 30 minutes later the engine is flooded because the fuel has boiled & the vapor has soaked the intake.. Wide Open Throttle & crank & it may start... Or not...  The real problem is modern fuel is formulated for EFI where the fuel doesn't need an Anti-boil additive cause fuel is kept under pressure so it can't boil....

Thermal block spacers, blocked heat to the intake, lots of patches help... What would really help is fuel from 1970....  Or EFI.... 

[-009-]

Before you start the car, can you pump the gas pedal and have someone watch the carb and see if fuel is being dispensed from the fuel bowl down the barrel into the intake?  Basically, when you hit the gas do you see a stream of fuel coming out of the jets?

Just went out and checked there is a steady stream of fuel when you pump the gas.

[Cuda Cody]

Yup, today's fuels suck compared to back in the 60's and early 70's.

When you try to start it and you know the bowls are full, pump the gas pedal once or twice holding the pedal open for about 2 seconds.  Then lift off the gas pedal leaving it untouched and don't turn the key over for at least 10 seconds.  That closes the butterflies and gives the fuel time to vaporize to become fumes.  Then when you start the engine it will suck those vapor fumes in much easier and start better. 

But what you describe sound like there's not fuel in the bowls.  After the car has sat for several days, try filling the bowls with fuel before turning it over with the key.  Or you can try spraying starting fluid down the bowl.  Either way, if it starts easier then you have an issue with the bowls being empty and that might be why you have to turn the engine over for so long before it will start. 

[kawahonda]

There's a thermal insulator that is included in Mike''s rebuild kits that just about nearly crushes the problem completely. Driving in the hot summer month without one is embarrassing...people look at you like your car isn't going to start and you start to get worried about the battery. After getting the insulator, it starts much, much easier and I don't give it a second chance driving it in the heat.

[Chryco Psycho]

Coolcarb makes one of the most effective spacers available , very thin too

[Cudajason]

Coolcarb makes one of the most effective spacers available , very thin too

yeah but...

[Brads70]

Electric fuel pump with a pressure regulator and a return line works good too.

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A quick followup with the heat soak issue. I installed an Edelbrock 1/2 heat insulator gasket PN: 9266 and that seems to have solved the problem for the most part. The car will now restart after the engine is at operating temp and 15-20 min after shutdown. Though it doesn't fire up with a flick of a key, it will eventually start. Don't yet trust shutting it off in the staging lanes.

I'll take a look at those recommended gaskets, in the near future.


Thank again.