hi sages- i have been wondering about the rules for sl6 carbs of the one and two barrel variety. have been reading the tech messages in the forum for years and combining them with my experiences i would draw the following conclusions. please feel free to comment or correct me. the one barrels seem tobe the 1920 and the 1945. have rebuilt a few and have bought new ones when the rebuilt ones wont stop leaking. the 1920 seems to get better mpg than the 1945. havent noticed any running problems with the 1945, but hear a lot of bad press about it. think my 76 feather has a one barrel 1920 and its the original, never had it off. 77 dodge aspen had a two barrel, had more power than a one barrel and still got good mpg. had to replace it 3 times in 360k miles. all the same problem- the idle circuit clogged up so it would only run on the high speed circuit in va on 95. dealer tried to make a home run wanted 600, put in a rebuilt from pep boys for 80 and it ran fine. one other time the two barrel crapped out (same idle circuit problem) in the lincoln tunnel in manhattan. think the sl6 two barrel is the same as the 318 2 barrel. pumping the accelerator and keeping the high speed circuit open kept it going until i got to a safe area outside the tunnel. folks in ny dont communicate in english but rather use hand gestures(sign language?). never had those problems with the one barrels. later i think for emissions purposes mopar went back to the one barrels. let me know what you think. regards bf

Usually I see this happen is that carbon vapor recovery can vomiting fine particles of carbon into carb (seen this happen on mine) best fix was install two filters, one between can and the carb and filter (for EFI) between fuel pump and carb (the smaller ones tend to have too coarse screen.

The idle jets is very tiny (around .5 mm or smaller).

Ever since, weber fuel bowl is clean.

Cheers, Wizard

Carter BBS '60 through '71 on cars and '74 on trucks, Holley 1920 '62 through '73, Holley 1945 '74 through '85, Holley 6145 (feedback version of 1945) '81 through '87. And there was a Stromberg WA in '63 only. There were some variants in markets outside North America (Holley 1922 in Argentina, Technico-Stromberg BXUV in Australia).
The throttle body eventually wears where the throttle shaft passes through, and requires rebushing; see here

Not necessarily. A carb in good condition works better than one in bad condition. All of the carb designs used on the slant-6 have their benefits and drawbacks.
The basic design is sound, but most of these were calibrated to squeak the cars past Federal emission control certification tests so they could be sold when new. They were not calibrated for smooth running or excellent driveability. Recalibration can greatly improve matters.
If your '76 has its original carb, it's a Holley 1945.
The Carter BBD used on the 2bbl engines is a good carb.
The idle circuit is not very difficult to clean and clear out. Occasionally you might get lucky, but "rebuilt" or "remanufactured" carbs from parts stores are generally a very poor choice; see this thread.
Conceptually, and a 273 or 318 2bbl can be made to work, but there are differences (choke linkage hookup, idle flow calibration, etc.) See Carter BBD operation and repair manual (pdf).

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