Not sure if they have gaskets in them didnt see it, but i know there is a spring inside them. Here is my story with mine hope it helps.
A few days ago my z w/ 4screw su's and e12-80 dizzy was doing the same thing. I changed everything from the plugs, cap, rotor, and fuel filter ran the car for a day and happened again. I pulled the carbs and took the tops off where noticed that the atf i had put in them (i was told its okay) had run out and they were dry causing them to drop really fast. I cleaned the carbs really good with carb cleaner, cleaned the floats pretty much every where i could get the carb cleaner nozzle into. Put them back together and filled them up a bit with the atf and the car ran even better. Once again few days later it was worse than ever. I couldn't make it over 35mph and cut off at every light. So i parked it and sat in a chair staring at the car and i thought let me pull the fuel pump and see what it looks like inside. I popped the top off it and bam! filled with 30yr old crud it was so caked up inside the filter it was impossible to tell there was a filter actually in side it. So i cleaned it out shook and drained the tank.I then bought 3 gallons of 100 octane and 6 gallons of 91, filled it up and had the best day of my z driving life. Been running great ever since.