Holley 2300 series carburetors were used on Chrysler small and big block Six Pack engines. This family of carburetors also provided the economy-minded two-barrel fuel mixing for numerous engines in the Chrysler line-up.

The standalone two-barrel 2300s had a full circle air cleaner base; that allowed the use of air cleaners with the same size mounting hole as some four-barrel carbs.  However the carburetors used on the Chrysler Six Pack engines have that large base removed, leaving a half-circle "D" shaped flange for the air cleaner to mount; this was essential to fit the carbs close enough together in the limited space atop the engine.

The center carburetor flows 350 cfm (cubic feet per minute) and is equipped with a choke plate (controlled by intake manifold heat) and an accelerator pump.  This carb also has a metering block that holds the replaceable jets and power valve.

The stock accelerator pump is a 30cc unit and is generally adequate for stock or lightly upgraded 340 Six Pack engines.  Different size nozzles, or "shooters", are available to increase the flow of the accelerator shot (at the cost of its duration).  Different cams, which actually operate the accelerator pump as the throttle opens, are also available; these also affect the flow and duration of the pump shot and can be the final piece in the tuning puzzle.

The outboard, or end carbs flow 500 cfm and use a metering plate instead of a metering block with jets.  This plate, which is thinner than the metering block in the center carburetor, has precisely sized "metering restrictions" for the idle and main fuel feeds performing the same function as the jets in the center carb.  They can be adjusted up by drilling out the restrictions to a larger size, but reducing generally means buying a new metering plate.

The end carbs, as supplied by Ma MoPar, did not have choke plates or accelerator pumps.  However Holley made performance/racing carbs designed to be used as a Six-pack but with a fully mechanical linkage instead of the more streetable but less deterministic vacuum linkage used by Chrysler; some of these outboard carburetors did come with accelerator pumps.