Technical SBC running too fast on start up

I'm not so good at fine tuning. I have a pretty stock 350 with an Edelbrock carb. Recently got the car worked on after a few months sleep and when you start it up the engine idles high for too long. It used to idle high then with a quick blip to the pedal, it would idle down. Now it idles high for a longer time even when you hit the pedal several times before it calms down. Any ideas? Seems like it shouldn't idle that high for that long.

 

Adjust the Choke??

 

Make sure the fast idle cam on the carb is free to move when you blip the throttle. Sounds like it is sticking.

 

Also, if you have an electric choke, and you had it apart at any time, check to make sure that you put it back together properly.

I have had quite a few people tinker with their choke, and put the cap and bimetallic spring back on wrong, and not just on Edelbrocks.

 

It the choke is open then possibly a vacuum leak at base of carb if the carb has been taken off at any time.

 

This is the business side of an electric choke. That spring is made out of two layers of metal, such that when electrical current is applied, it attempts to unwind.

From this view, the hook at the end of the spring moves counterclockwise when heated by electricity.

That hook needs to be around the lever that is in tha cast metal part of the choke housing, so it can pull the choke open when you step on the throttle. I cannot count how many that I have seen where the hook is just on the other side of the lever. When it is there, it won't pull the choke open. The hook will still move, allowing the choke to open when air is pulled past it, maybe, or maybe not.

This can be checked my loosening the torx screws a little. If you rotate the black cap clockwise, it should open the choke. If it does not, it is put together wong. You can double check this by rotating the cap counterclockwise. If that closes the choke, then the hook is definitely on the wrong side of the lever.

Now, if you have a manual choke, take a picture of the linkages on both sides of the carburetor, and post them. We might be able to spot the issue.

 

Mine did that for a long time before I realized it was a vacuum leak

 

How long is long, and did it get colder there recently?

Since you made no mention of releasing a choke cable yourself, we can only assume that this has an electric choke.

This electric choke is connected to 12V constant, when the key is on (not to the coil lead). The choke itself is a resistance load, that functions by the heat produced by that resistance. It is therefore dependent on ambient (outdoor) temperature, as well. The colder it gets where you are, the longer the choke will stay on, and the longer it will be on high-idle. Even a few degrees drop in temperature makes a difference. If the choke was adjusted when it was 80º, and you fire up the car at 60º it will perform differently.

Definitely check for vacuum leaks. If none are found, both the high-idle speed and duration are adjustable, with screwdrivers.

 

Lots of good advice already on getting the choke adjusted. Just be advised that there's probably two idle speed adjuster screws to deal with.

One is for the "curb idle" (low speed). That's set with the choke fully open and engine at normal operating temperature. The other is the "high speed" idle adjustment which is best set on a cold engine with the choke closed to a specified amount. This helps keeps the engine running with the enriched condition that the choke supplies on a cold start.

 

Here is video for fast idle speed adjustment on Edelbrock carb.

 

This is another brand carb but video shows how to adjust choke.

 

Thanks for all the replies. It is an electric choke. After the first 2 replies I checked Google for Edelbrock electric choke adjustments. I took the air cleaner off and the blade would not close. When I moved the throttle rod it freed the blade to close. Maybe something was binding there?
I loosened the 3 screws on the choke cover and turned it all the way counter clockwise then back about a mark and a half. I started it up and it went to about 2800 rpm according to my tach. I hit the gas once and it idled down correctly, so that adjustment seemed to help. Yesterday I had to hit the gas about 5 or 6 times before it idled down. Now I have to get that 2800 down. Looks like I'll have to adjust the high idle screw.
Outside temperature has not varied much here....about upper 70's to mid 80's.
I'll try it again tomorrow and see if it does the same

 

At this point, you probably only need to adjust the fast idle speed screw down.

That is shown here:

Making the part of the screw that is shown stick out farther raises the fast idle. Backing it out lowers it.

Shown in the picture, the choke is ON, and that screw is on the tallest portion of the cam.

If you are at 2800 RPM on a "cold" start, I would back the screw out three full turns, and try tomorrow. Adjust from there, as necessary.

 

I totally removed my choke and don't have any issues even in cold weather. (It just don't get that cold here in the winter...and you're further south than me.)
Did it just start doing it???...or after you might have.................done-some-work on something under the hood?
6sally6

 

Someone else did some work....under the hood.

 

Can you take it back TO THEM?.......I would, and find out just what they......."adjusted"! Watch them and learn what NOT to do!!!
6sally6

 

Depending on where you live is how I set a choke. I hold the throttle open then turn the choke plastic cap slowly into the fast idle cam to the first setting and tighten the holding screws on the plastic choke heater cover. The choke butterfly is only partially closed. For me it’s the faster idle for a short time then the bi-metal spring opens the butterfly and drops the idle back to normal warm engine..