Holley's science vs Edelbrock simplicity?

sr71mopar said

They sure aren't double pumpers. Let me rephrase that. It still take air flow to open the air flap/door thing whatever it is.

Click to expand...

As Fishmen said, they are mechanical secondaries with an air valve.

Holley is the only carb I know of with a vacuum opened secondary throttle blades. Just like the TQ and the Q-jet which also have mechanical secondaries.