Carburetor help and or advice

I have a 66 GMC with what I Believe to be a 230 straight 6.  It has a Carter single barrel Carburetor that I rebuilt.  there is a open hole in the top of the Carb with a plunger that comes up when the accelerator is pushed.  I can see that it does not currently seal off the whole when it moves up, and I do not know if it is suppose to?  my van is running very rich at idle as well as when I am driving and accelerating.  I have an electronic distributor (i did not replace or adjust)... I am looking for help and guidance.
attached are two pictures of the hole

That sure is my favorite carburetor,,,,,,,,I will get you some pictures,,,,,,that hole is the bowl vent,,,,,should be a fiber washer on a screw attached to the accelerator link,,,,idea is that at idle its open a little then goes up to shut off hole when you step on gas,,,,,,,,,accelerator pump is vacuum operated,,,,,so any problems there causes intake to suck gas out of bowl and run rich,,,,,,so what did you do to rebuild it?

I purchased a rebuild kit from NAPA. Watched Mike's Carburetor rebuild on YouTube. The carb had a lot of garbage clogging it. But there is no fiber washer. There is just a metal washer that doesn't seal the hole. I suppose I could fashion one and replace the other. I will try to send a picture of how it appears now.

but thats not your problem,,,,,,,was there a check ball in the pump,,,,,,,,did you make sure the pump was flat,,,,,,,,was the float good,,,,,,,did you get the correct needle and seat,,,,,,did you set the float level correct,,,,,,,,,did it have this problem before you worked on it,,,,,,,,is there a puddle of gas down the barrel after you shut off the engine,,,,,,,you are getting too much gas from somewhere,,,,,whats the choke doing?

Check ball with a weight in a port yes ( none in the accelerator pump itself). Pump seating flat and free, the float looked great and adjusted fine. I used the same shutoff needle because the one in the kit wasn't the correct one. There was a puddle of gas in the bottom of the intake manifold when I removed it. Yes I had that problem plus more before I rebuilt it. It was fouling out the last spark plug before and didn't idle wells. The choke is open (disconnected). I open the cover to cloak on cold starts

we will get there,,,,I kinda like to dial things in as I get facts and clues,,,,,,we are looking for where the extra gas is coming from,,,,,,,,,lots of places it can get to those spark plugs and them spark plugs dont like extra gas,,,,,,,now you could be using a 50 year old needle and expecting it to work?    how about this metering rod,,,,you adjust the pump,,,,,, THEN,,,,,,you adjust it,,,,,,