Holley Carb & Fuel line question...

No, no one drill or tapped it, it' new. I just wondered if it should be capped? I didn't know if I left it as is if it would be drawing in air from the outside?

Also, about the fuel pressure gauge. Like I say, it screws in pretty far. Is that going to restrict gas? Should I use some of that white tape stuff to seal better?

Thanks!