Adapter rings- does that mean that the 216's had smaller intake runners? I don't want to do anything to restrict airflow...thanks!
Yes. the runners and ports are smaller. The carb for a 216 is also smaller and won't bolt up to a 235/261 manifold. Nor will a wider 235/261 tbolt up to a smaller 216 manifold.
There are many reports of dual 216 carb's working very well on a 235 and also being workable on a 261.
Altho harder to find, stock 261 Rochester carbs have larger ventri's and jets than the same bolt pattern sized 235's but when you go duals on a 261 it has been posted that dual 235 carbs worked better.
You run into decreased air flow when you over carb
these old Stovebolt powerplants.
