Kingston 5 ball help

[Simon Anderson]

Help and ideas needed,
I have recently acquired a Kingston Model E-5 ball carby.
I have gone through and rebuilt it, new balls and seated, new butterfly shaft, reseated needle and seat and set the float height to 1mm below the top of the jet.
It  starts well and once you bring the rpm down to a more idle speed the carby will start to drip out the bottom air intake and start to lean out.
I thought that the float height maybe the cause of the problem so I went up then down with the same issue.
Next, looked at the intake valve closing timing, I made the tappet clearance a lot larger to make the valve close earlier. The thinking here is that as that maybe positive air pushing back into the manifold which is in turn pushing a small amount of fuel out of the jet. It still drips at idle
What have I missed?