On a Gurtner carb.
It is very very simple to get wrong... and could very well be your problem.
The Gurtner "engineers" made it VERY easy to install the float wrong.
Take it back apart.
The needle in the float goes in with the pointed end UP... it is easy to put it in upside down
THATS NOT ALL.
The other thing izzzzzz... The needle is supposed to go into the tiny hole in the bottom... and it is VERY easy for the needle to MISS the hole and slide down the side of the little cone that the hole is in... and you can't tell.
You need to play little games with it and stick it in several times and wiggle it up and down while looking at how the float slides up and down... till you are SURE the needle is in the hole.
That might be your problem.