I need a little enlightenment on this Holley carb

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Whether equipped with a Holley 1920 or a Carter BBS, the '60-'66 A-bodies (Dart, Valiant, Lancer, Barracuda) with Slant-6 engines -- except '65 and '66 models with factory A/C -- had a rotating-rod throttle linkage arrangement that requires a carburetor with the correct throttle lever fitting to accept the rod.

The BBS and the 1920 both have their own characteristic dammit-points, but the BBS has fewer of them…only one, in fact: if the screws holding the three castings together are overtightened, the casting flanges can warp over many years. Usually not a problem as long as the same castings are used together (and using two gaskets at each flange tends to solve whatever minor air leaks might result from the warpage). The BBS holds up better in the long run; eventually the 1920s reach a point where they're just plain done and cannot be brought back from the dead without totally ridiculous amounts of money and effort, and sometimes not even then.

Better than the BBS and 1920 both was the Bendix Stromberg model W, which unfortunately was used only in one year (1963) and only on bigger cars (B- and C-bodies). That's a very durably good-running carb with very nice quality castings, no gasket flanges below fuel level, etc.

The first-version Holley 1920s on the Slant-6 engines of 1962-'63 weren't radically different, but had some better design and build in them than the '64-up carbs. As the '60s went on and especially in the '70-'73 timeframe, the Holley 1920 was progressively made cheaper, nastier and more problematic. Meanwhile, the BBS got progressively improved; the final version (used on '71 198s) is one of my favourite swap-on carbs.

The original poster's carb is a "remanufactured" 1973 Holley 1920 1-barrel -- one of the cruddiest versions of that carb, made much worse by the abusive "remanufacturing" process. Castings aggressively blast-cleaned...passivation coating gone; open-pore potmetal of poor quality in the first place will rapidly turn into powdery white "metal mould" corrosion.