I have a 75 F250 with a mild built 460. When I start the truck after sitting/cold start. It cranks and fires up immediately. After driving and the engine is at normal operating temperature, I can turn it off, try to start it again right away but have to have the gas pedal to the floor while cranking for 5-6 seconds. Once it starts, it does not sputter, idle rough or die. Same thing applies if I wait for say 30 minutes or so and the engine is still warm...long crank time.

It always runs great, idles smooth, and has excellent acceleration. I do notice that after I have been driving and I park it, there is a smell of gas which will disappear after a while. No leaks, anywhere. Not around the carb, fuel lines, fuel pump, filter, tank...nothing.

Not sure if it is related or not, but...if I start it cold, it has a normal fast idle. If I tap the gas pedal, it drops down to about 650 rpms which is close to a "normal" idle speed. After I drive it and it warms up, the idle in neutral is about 750 rpms.

It has an Edelbrock 1406 carb with larger secondary jets (I had it done at a shop - don't remember what size they are).

Am I getting too much fuel in the carb once it warms up? Is this a symptom of the choke not opening up all the way? Looking for some direction on where to start to find the cause.

Thanks.

 

Your problem is that Edelbrock carb. Its a common problem with them. Someone may know a fix, but I've never seen one.

Nathan

 

Cant say it's the Edelbrock carb, because my Holley 600 does the same thing....EXACT SAME THING.

 

Common carb issue, however the cause is often different between types.

Myfreeford, edelbrock carb on an aluminum manifold? Just a gasket between the manifold and the carb? If yes, get a heat sink between the two. One of those thick gaskets, a phenolic spacer, something like that. I don't recommend the ones that are a pile of plates and gaskets they tend to break carbs.

Secondly double check float level.

On the holley is tends to be a power valve + high float level issue

 

I agree, your carb is percolating into the intake.
This is why you smell gas but don't see any.
Then you have to hold the throttle wide open to clear the flooding.
A spacer can help.
So can a heat shield (an aluminum reflector plate that bolts under the carb)
These things haven't been common since the early days of emissions mandates and subsequent skyrocketing under hood temperatures.
I'm old enough to remember those nightmares.

 

Are there different thicknesses in a heat spacer that I would want to consider? Any brand better than others?

Thanks. This is good info.

 

Do you want an open, split, or four barrel spacer?
You have an Edelbrock carb.
They make phenolic and wood spacers in 1/2, 3/4, and 1" thicknesses.
Make sure to get a new throttle cable bracket (or riser) so the pull is at the correct angle.

 

Material is more important then thickness when it comes to spacers and heat.

 

Honestly, I don't know what kind of spacer I want/need. I've never knowingly needed one. I have an Edelbrock 1406 and a Performer 460 manifold. I am not familiar with which material is better for this kind of issue.

Do I need to use an Edelbrock spacer? What material will perform the best? As for thickness, is it better go go thicker?

 

Given that it's a truck I would assume four bore or divided plenum depending on what intake manifold you have.
In which case I only see 1/2" wood from Edelbrock but they do have four hole in 1" phenolic.
There are plenty of other manufacturers.

Separation is going to help torque by keeping velocity up at part throttle.

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