On the moderately tuned 261 in my 37pu, I tried a whole bunch of carb and manifold combos in the last 6 years.Started with 2 Rochesters on a heated Offy manifold, 2 Pinto Holleys on the same manifold . I then bought a Clifford heated 4bbl maniflod. First tried a 500 4bbl Edelbrock,a 500 Carter AFB, a Holley 600 4bbl ,and now a Rochester 4gc off a 64 283.Spent enough time to tune all the carbs and actually there is little power difference between them that you can feel.The first set up with the Rochester B's ran very well on the home made water heated Offy manifold.Used #57 main jets,drilled out the air bleed on the venturi cluster .002 more, and reduced the size of the power valve orfice to .025 from the stock .032.The engine had smooth seamless power, no flatspots and about 18mpg with 3.36 gears.However on hard acceleration in first gear, gas would slosh up the accelerator pump shaft cavity and spill on the manifold.Not really a fire danger, but it stunk, yuk.Perhaps a set of Carters or a pair of glass bowl Holleys would work well while keeping the old time look if that waht you like.On my engine ,the 500 Edelbrock always had a momentary bog as the secondaries opened. No amount of jetting changes or air valve fiddling solved the bog.The 600 Holley was too large but produced good power and no bog as the vacuum secondaries started to open .On some engines,Holley 4bbls, like the 390 or my 600 need a lot of air bleed changes to get proper mixture during part throttle cruising. On all carbs, changing main jet sizes generally won't cure part throttle driveability problems. You must get into the air bleeds to make a meaningful difference.Remember the Clifford 4bbl intake has a large plenum under the carb. the plenum acts like a holding cell for air fuel mixture, so the carb may act bigger than it is.As with most modifications, the engine tuners preference plays a large part in deciding what is good or bad.An engine that bogs just slightly as the pedal is floored then picks suddenly, may feel faster than a smooth transition.Of course the smooth one has faster acceleration.Sometimes a carb that works great on one engine ,won't perform well on another engine that is similar.The current old Rochester 4bbl suits me fine but is really no better than the 2 old Rochester B's for power and fuel mileage.
