318 2bbl won't idle without choke

When I first got my Aussie Charger many years ago it idled like **** and would take a while to start when hot. I rebuilt the carb (2 barrel carter ) two or three times with no change. I was given a second hand carter and I rebuilt that and all my issues were solved.I could not see any issues with the first carb but suspect it had a crack in it somewhere that would open up more when hot, or a warp somewhere.