The issue with fuel evaporation (due to ethanol in the fuel) is worse than it used to be (like when the car was newer). I'm not sure if there are any "ethanol shield" additives which might help this issue.
Our '66 Newport 383 came with a Stromberg WWC3 carb and I liked the general design of the carb compared to the Carter BBD (larger version) that was used interchangeably with the WWC3 carb, back then.
A few things to look for. Due to the "top hat" aire cleaner design, people tended to tork-down on the air cleaner wing nut. That extra tork resultingly pulled up on the center of the air horn where the carb stud was screwed in. It looks substantial enough, but after several years, CAN deform that area upward. Might not sound like a "big deal", BUT that area is also where the back of the float bowl seals AND carries the vac signal to the power valve (which is part of the air horn assy). So, first thing that is lost is fuel economy as the power valve is always open (getting no vac to close it when not needed). So ours got 12 mpg, no matter what.
The second area is the sealing of the rear of the float bowl. In some choke plate angles, during warm-up, raw fuel can actually be pulled out of the float bowl into the venturi area, which can really make for rich mixtures. I experienced that one winter in 1973. Once the engine was warm and the choke was more open, no issues.
Other than these two things, to me, the Stromberg was a fully-modern design carb. Everything looked good to me and it operated well. Even better after I got the choke pull-off to open things up a bit quicker. But, alas, I upgraded it to a Holley 2210 to get away from the warped air horn issues (Chrysler did issue a "fix kit" for the same issueson the Holley, though). Plus the Holley got better fuel economy on the highway with better off-idle throttle response. BTAIM
The "archaic-looking" BBD 1.5 looked more "out of the 1950s", to me. Being a metering rod carb, it can have more flexibility in turning, BUT the parts to do so were only in the Chrysler parts dept, with no guidance of what was what from Chrysler or Carter.
As it's history was "from the 1950s", when air cleaners were held on by band clamps around the air horn, they adapted to the later-style air cleaner by drilling a few holes in the band clamp area, then bending up some large diameter "wire"/rod to go in holes in the band clamp area, and then curve upward to hold the air cleaner stud in it. So THAT kept the forces from the center of the air horn.
ONE other thing to look at can be . . . in some carb designs from the 1950s, there were some fuel-carrying passages in the float bowl housings which were drilled and then plugged with ball bearings and a sealing solder, before surrounding metal was peened to keep them in place. Ethanol can erode the solder and let the ball-plugs fall out, which will quickly empty the float bowl. Inspect the carb float bowl section for any such plugs, which usually are on the front side of the casting. IF you notice any seeps, get them plugged up with a gasoline-resistant sealer quickly.
For the ultimate test, after the car has been sitting, remove the air cleaner and manually work the accel linkage to check for accel pump shot. Might be one shot, but if any ones to follow it spurt air, that's an empty float bowl. But as I recall, the hoe the accel pump feeds from is below the level of the main jets? Just some thing to consider.
Just some thoughts and experiences,
CBODY67
