Re: Rochester ????
The Rochester two barrel carbs are either the 2G, the 2GC, or the 2GV. The 2G was a chokeless version intended for the center carb in a 3- deuces configuration. Like on a GTO. The 2GC is the standard thermal choke version, and requires a stock gm manifold to work the choke right. It had an exhaust passage that came up through the manifold to the choke housing. The 2GV has a vacuum operated choke. There was a little thermostat that sent vacuum to the choke to open it as the engine warmed up. You can buy these. Either the 2GC or 2GV can be converted to manual choke with a simple kit from an auto parts store. The 2G series is really easy to tune, and should not have to be rejetted for changes in displacement unless you are going to an EGR'd engine. The adjustments available are for curb idle speed and curb idle mixture (screws and needle valves), part throttle mixture (a power valve spring available in 6 weights and variously sized metering rods), accelerator pump (bend the rod for more or less), float level (higher means richer), and main jet (change sizes). You should really only need to change the curb idle and accelerator pump settings, and maybe float level if you change engines within 50 cubic inches of the original. You will want a pre-'75 model because they had emissions stuff after that.
The aircleaner can be adapted with a plastic adaptor ring meant for adapting Holley- sized air cleaners to Rochester cleaners. They cost about 5 bucks. I got mine at my local Napa. I use a chrome ring air cleaner on mine. Mine is on a Buick 225 V6, and is the stock carb. It is easy to keep tuned and gets decent milage. I just bought an Offenhauser Qjet intake and a Quadrajet carb to replace it, though, so I can get more HP and better milage. The Qjet has smaller primary barrels and huge secondarys, and the offy manifold flows better than stock. The smaller primarys give better off-idle response than the 2GC. The qjet will also operate at all kinds of wierd angles. I will be interested in selling the 2G that I have. I just rebuilt it. It has been converted to manual choke. I will keep it around until I get the Qjet and Offy tuned, though.
The only real shortcoming to a 2G series is that they are a little simple and they don't have as good of fuel economy at low speed part and full throttle acceleration as a 4 barrel because they rely soley on the accelerator pump for acceleration fuel. They stumble a lot if you lug the engine. If you have good driving habits, they give no problem. They idle as smooth as glass. They are really easy to rebuild and tune.
I recommend getting a carb tuning book and reading it. It is not rocket science (well, actually it sort of is), and you could probably get your BBD running right again by kitting it and tuning it up.
1955 Willys CJ5 Buick 225 V6 160HP 270ft-lbs, T90 trans, Warn OD, PTO winch, Spicer 18 T Case, RS9000's, Dana 25F/ 44R,
5.38:1 gears, 11" brakes, Bestop Supertop, Hurculiner