I had a similar problem with hissing from the carburetor and poor performance under load. It turned out that the bowl on the Rochester B was warped just enough to suck in some air and make a hissing sound. I resolved it by changing to a Carter YF.


1956 Chevy 3200, 1/2 Ton, 235 CI
https://photos.app.goo.gl/TQQo1YnFjs3U7xB57