Pox those DCNF's are not supposed to do that, actually they were marketed where you could drive them on the street and come up to a stop and slam on the brakes and have a perfect idle. In both cases stated above it's fuel starvation on hard cornering, float level maybe a bit low, or fuel pump is weak, but most deffo fuel starvation as Mr. Oval says.
werent dcnf's deigned to have the float bowl oriented to the front of the car or 90 degrees from crank centre line on ferraris and fiats in the first place?, hence the age old issue of side orienation on an a/c flat 4 causing fueling issues as the movement of fuel in the bowls on hard cornering is adverse to its original design. I think!!! there was a newly designed float which cured this problem to a degree but i could be wrong. berg tricked out and reworked 42's under the guise of their "42 specials" great old school carbs, i think for "normal" driveability they are very hard to beat, they run really smoooooth. just dont show em a corner lol.