vegiguy,
What year 235?
Did you try the carburetor idle-rpm adjustment fter a good tune-up:
- newly set points and plugs
- valve lash adjustment on a completely warmed-up engine
- timing to maximum vacuum
- setting carburetor idle mixture to maximum vacuum
I set my 1954/55 trucks' idle speeds at 450-500rpm as specified in the manuals (I do this even with dual carburetors).
My 1954 235 with Hydra-Matic transmission calls for 400-450rpm. After a tuneup, I used that range.
I do not know if I could have brought them down to the 400rpm 1941 specification.
A lot of people prefer the Carters over the Rochesters. I use original-specification Rochesters in my 54 trucks (yes, they "weep"), but I had a Carter on my 1948 Panel (back in the 60s - it worked fine).