What most of you all seem to have forgotten, or (more than likely) just plain didn't/don't know, is most of the cube type carbs have one or more non-replaceable check valves in em. When they go bad all the rebuild/G&D kits in the world ain't gonna help, nor will tweekin any screws.
It ain't rocket science!
'Course if yer house has more wheels than yer truck...
" Old age ain't for sissies "