Need Carb Help

[Bdrennan]

Ok, I am fighting what I thought was heat soak, but now I'm not sure.

I put an edelbrock 1406 carb on my car and it runs and drives great... No issues.  However, if the car sits for a couple of weeks, I can't get it to start for anything.  Just cranks and cranks.  I have to end up putting a little gas in the top of the carb to get it to start.  Once it does, again, runs great and will continue to fire right up unless it sits for a couple of weeks.

Fuel pump isn't but a few years old.  

When it sits and I pull the air cleaner I don't notice any squirting of fuel when I pump the accelerator.  From everything I read it sounds like the carb needs to be rebuilt, but it really it is only a few years old and it was new when I put it on.  Could this really need to be rebuilt?

 

[Hemikiller]

Edelbrock is notorious for this. I had a truck that I'd only use once every couple weeks and I always had to prime the carb. Rebuilding it won't help. 

 

[Don C]

+1, if you don't want to crank it until the mechanical fuel pump fills the carburetor bowls install an electric fuel pump near the gas tank. Turn the key on, wait 10 or 15 seconds, crank it. Also solves any potential vapor lock problems in warmer climates.

 

[goodnigh]

Same problem here.  Sets for a couple weeks all the gas drains back to the tank.

We were going to put a check valve in the line.  You would think the fuel pump

would prevent this.  Carb is a Holley 770 Street Avenger.  Also wired the choke

to the alternator stator I think so the choke won't get power until the engine

is running.

mike

 

[Don C]

The mechanical fuel pump does have a check valve to prevent backflow to the tank. Because the float valve sets at the top of the fuel  bowl fuel cannot run from the bowl back to the tank, unless the valve seat gasket is leaking or not tightened down on two barrel carburetors, then some could run back into the fuel line. However, if the check valve is leaking in the fuel pump the pump will not function very well. If your fuel is disappearing from the fuel bowl it is into the intake manifold or onto the intake manifold from  a leaking component or porous casting.

 

[autonomousbronco]

You can also always try a phenolic spacer for the carb (measure hood clearance first)...it’ll keep it cooler during run times and prevent the fuel from boiling off post shutdown. 

 

[mbrew2]

Not a carb guru, but here's my advise from experience. My car had an eldelbrock 1406 on it when I bought it.  Thought it ran OK but had constant problems with running rich and bad heat soak when it got hot. Tried everything anybody suggested. Finally gave up and swapped it for a Summit carb with electric choke. Presto! All problems solved. Cold - turn switch on, pump accelerator once - fires right up. Hot - don't pump, just crank - starts like its fuel injected. Also discovered that Eldebrock was sensitive to fuel pressure which made it almost impossible to tune. My fuel pump was producing almost 8 psi. Installed a fuel pressure regulator set at 6.5 to 6.75 psi and never looked back. Car regularly sits for weeks and still always starts right up. Only time it didn't, it had sat for 6 weeks with front wheels on ramps, even then, it started, but died until drained fuel lines filled. I've run Holley 670 and 770 Street avengers and 750 double pumpers and while the Summit carb may not be the ultimate performance carb, it gets the job done and cranks when I want it to - every time. 

 

[Stanglover]

I too am no carb guru, far from it, but as I too have a Holley 670 S/A, I have direct experience with this issue. I cannot comment on the Edelbrock carb as I've never used one, but I have to assume there is a vent tube on the fuel bowl like the Holley. When my car sits for an extended period, the fuel in the primary bowl will have evaporated. I don't think much if any will have leaked into the intake, but possible. After the winter hibernation, I poor about  a 1/4 cup of fuel carefully through the vent tube and it will start within a couple of cranks.

As for hot start problems, I had that too. There has been much discussion on this, but in a nutshell, my solution was to block off the exhaust heat cross over, stock manifold, and add a 1" thick fiber spacer, Problem solved, never had that issue since. It is a lot of work to block off the crossover, but adding a phenolic or fiber spacer will help, but not totally fix the issue. It's not when the engine is running,  it's when it sits after.

 

[Kilgon]

+1, if you don't want to crank it until the mechanical fuel pump fills the carburetor bowls install an electric fuel pump near the gas tank. Turn the key on, wait 10 or 15 seconds, crank it. Also solves any potential vapor lock problems in warmer climates.

+1 with Don.  A electric pump is the only way to guaranty a full bowl of fuel when you go to start the car regardless of how long it's been sitting.  Some of the other advantages of a electric pump is that it will allow you to see any fuel leaks you may have before starting the engine and if you wire in a separate switch it can be used as an anti theft device.    

 

[midlife]

I myself use Bic lighters to find any fuel leaks ...

 

[TommyK]

I myself use Bic lighters to find any fuel leaks ...

I guess that explains the no eyebrows thing

 

[autonomousbronco]

I myself use Bic lighters to find any fuel leaks ...

A very effective method.

 

[Animal Lawyer]

A very effective method.

of finding the leak or losing the eyebrows?

 

[autonomousbronco]

of finding the leak or losing the eyebrows?

Yes.