Quote: btw, there are TONS of holley carbs that do not have this valved vent line on them. the majority of 4bbl holley carbs just use the vent that is in the air horn.
why would a six pack carb need a special vent for the center? doesnt make sense. should operate the same as any old run of the mill holly 44bl
Every Mopar OEM Holley, including the early center six-pack carbs, has had an external fuel bowl vent valve of some sorts, either a small rubber “hat” over a hole or the later enclosed valve and nipple (E.C.S.) It is not intended to be/or replace the primary balanced bowl vent. On a street application it’s purpose is to provide, external to the air cleaner, another bowl vent path to atmospheric pressure thus ensuring, under hot at rest conditions, that pressures above the fuel can’t build during heat soak. Competition applications usually don’t have the same concerns and therefore carbs built for that purpose don’t have them. Aftermarket carburetors, including those from Holley, I’ve purchased over the years, designed for street/street-strip use, all had an external enclosed bowl vent valve. If not running an evaporative recovery system of some kind it is to be left open.
Blocking off or eliminating the external vent valve system will not alter the running performance at all in most cases, may contribute to hard starting hot however under curtain street use conditions.
