In the years which Chrysler put Holley 4160 600cfm carbs on the 440 New Yorkers and Imperials, back when the cars were newer, in the later 1960s, the local Chrysler dealer would routinely swap the Holleys out for a Carter 4bbl from a model year they used Carters on those base 440s. Reason? It seems that Holleys, back then, had a poor reputation for durability of the seals and gaskets, such that they needed a rebuild about every year or so. So, as the Carters had no such issues, the customers were satisfied to have a very reliable Carter than a "troublesome" Holley on their cars. That was then.
In the earlier 1980s, I bought a new Holley 4160 for my Camaro upgrade. No issues with leakage or such, other than ethanol (apparently) on the accel pump diaphram (which is on the bottom of the float bowl, so a leak there could potentially drain the front float bowl onto the intake manifold . . . NOT GOOD! I later changed that carb to a 4175 OEM-spec carb and it ran well, but had similar issues with the accel pump diaphram. SO, an ethanol-resistant accel pump diaphram is important to have on those Holleys, from my experiences.
So, as much of a perf heritage as Holley 4bbl tend to have, I might now lean more toward an Edelbrock AVS2 or Street Demon, in the approx 600cfm sizing. A SD with the phenolic float bowl, which is a clone of the Carter TQ. The SD has the triple-boost primary venturis (ala Rochester QJet) as the AVS2 has the annular discharge primary venturis (ala 1960s Ford OEM 4bbls, and current Summit-branded 4bbls). Both carbs have OEM connections to Chrysler-used carbs, so it might be a toss-up or which one is less expensive at the time you get ready to buy one? Watch the sales at Summit or Jegs!
Just some thoughts,
CBODY67
