Lean? Not for the light load cruise mixture, but in low vacuum situations when the power valve opens,it may not provide a rich enough mixture for sustained full throttle operation. Carbs respond to air flow, in theory the carb doesn't care what size the engine is.Heavy truck carbs generally have richer jetting to accomodate constant full throttle, full load operation.The 261's came with a Rochester B carb slightly larger in size than a 235 type, a 1-9/16 throttle bore.The carb you have should work ok for casual driving, but will limit the power somewhat.
