Before you take the carb apart, talk with Tom Langdon. If the carbs are relatively new and Langdon will honor/provide a warranty, he will not like hearing you opened up a carb.
You are right about those carbs being nicely matched with a 235.
Mine were very economical on a 261: 18 MPG when I drove smoothly and 12 MPG when I was speeding. The carbs were too small for my 261, so I switched to something else.
