I had ZTherapy HS6 carbs on my 164. I couldn't get the
car to keep an idle and it smoked at WOT at high RPMs. I
fiddled lots with everything and never got the car to run
right. I can fiddle with the SUs on my 144 and get things
to run right so I don't think that it is only that I just
don't know what to do.

I put the original strombergs back on after fiddling with
them and the car runs better than it ever did with the SUs.

I had to replace a diaphram and synchronize bimetalic
strip thingies (one of which was actually on backwards
originally.) and I replaced a couple of other gaskets but
otherwise they were in solid shape to begin with.

My car also had lots of other problems that I at first
thought were the fault of the carbs. Is you manifold
straight and all the studs in place? Have you checked
the nuts on the manifold?
chris