whats a valve job?

[iwantawd]

what is it and what does it do. i hear things like 5 angle valve job and stuff like that.

 

[97GSTURBO]

Valve job= Getting valves replaced, or resurfacing the seat on the valves to allow a better seal, or allow more air flow... 5-angle valve job is where they (the machine shop) cut 5 angles on the valve to allow more air flow.

 

[UndergroundR32]

From what I've been told a 5 angle valve job is completely unnecessary unless you're getting into serious power numbers (500+). I believe the stock head has a 3 angle valve job, correct me if I'm wrong.