If you've done carb work there is a major pitfall many RD owners run into. This happened to me with pretty much the same issue your having. It involves your float bowls. Look at the float bowls. They look pretty much alike, but with very close inpection you will find they are not alike. One has a hole that the other doesn't have. If the bowls are reversed you will have problems. Now it's been a long time since I dealt with this, so I'm going from very old memory. So I may not even remember the details exactly.
On the bottom of you carbs, you have a long tube. When you put on the float bowls this long tube goes into the round hole in the float bowl. Look at each float bowl very very close. At the base of the float bowl where the tube goes. Look at the bottom. You will find one float bowl has a hole and one doesn't. Get these bowls reversed and in the wrong place and you got grief.
