I have one of these quadrajets with the slotted secondaries, and have seen it written that these were high performance models.

Does anyone know Which year/models of cars came with these carbs?

I have one of these quadrajets with the slotted secondaries, and have seen it written that these were high performance models.

Does anyone know Which year/models of cars came with these carbs?

my 1970 Formula 400 came with a q-jet with slotted air valves.

The slotted secondaries were used on many carburetors. Check the carburetor identification number to obtain the original application.

Jon.

Good carburetion is fuelish hot air.

Pontiac q-jets used slotted secondary flaps until 1975. Most of the 75 and newer Pontiac carbs had solid flaps and the fuel supply holes directly in line with the flaps so they are exposed to the underside of them. The slotted flaps in the early carbs are actually a bit too large and let in a lot of air when the secondaries are quickly opened. In actual operation the fuel runs almost directly down the inside of the secondaries, the large slots are not needed. We've had much better success using very small notches or relocating the fuel supply holes under solid flaps....Cliff