You'll have to be a little more specific - I'm more of an import guy so I'm a little lost around carbs. I know what an xcel pump is, but how do you change the stroke?
Go on line and look up Edlebrock 1406 carb discription. It "should" show you a brakedown picture of your carb/acel pump. When you move your throttle by hand you will see an arm through the linkage that pushes a plunger into the bowl area. This has a pump adjuster (should be a spring around it) that if not correct could allow too much fuel from the bowl to enter into the rods which floods.