That 10884 number comes up as a metering block for a 600 Holley carburetor and if you don't know the model number of the Holley carb is on the front driver side of the choke tower. It will have something like 1850-5 for an example and then there will be like four numbers underneath it for example 3005. The top number bill be the model number of the carburetor and the number underneath it is the date it was made.
The number after the dash will be higher the newer it is made. If its a common Holley 4160 with side hung fuel bowls it would most likely show a 1850- which is a manual choke and there is the other one a 80457- which is a electric choke.
Is your carb one of those? It sounds like something is either binding up on your choke on the fast idle cam perhaps and a few other things could be causing a binding issue. If your using an electric choke version then when you first hit the throttle to prime the engine it will automatically set the choke on the fast idle cam to have it on fast idle and as the electric coil will start to heat up and it will slowly open up the choke plate but it will remain on the fast idle until you hit the throttle again and then the fast idle cam which is on the passenger side on the bottom side of the throttle plate outer side.
The thing on electric chokes you have to make sure the fast idle rpm setting is not setup to high with the fast idle speed screw as when you let it off and if the fast idle screw is screwed in far enough for a certain rpm range then when it drops down the bottom of the screw can sometimes just barely touch the fast idle cam on the lowest setting to where it normally should clear to the cam is all the way down and it will be the fast idle screw can make contact with it just enough to keep the primary idle from setting down to the primary speed from the primary idle screw.
If you can't get the proper rpm setting with your fast idle screw without it contacting the fast idle cam in the fully open position after the electric choke coil has opened up the choke plate all the way then sometimes you might have to sand just a little bit off the last bottom ramp of the fast idle cam to allow more clearance room for your choke fast idle screw so it does not contact the fast idle cam in the full open up position.
Normally in my experience if I get a 1300 or so high rpm it should clear but it can differ from carb to carb depending on the factory tolerances. Check the other things mentioned above as well.
