Why? Just because that is the way it is done. When the Tri Power Manifold Left the Assembly Line the Automated Drills and Taps had just created New Threads! So why would you want to leave Rust, Sealant, Dirt and Grit in the Holes to get Dislodged and dropped into the Intake Runners? Trust me, that is the reason most Carb Studs do not come out by hand!
