Three angle valve job, what is it and what does it do??

[Anonymous]

First off thank you for not laughing too entirely much because you know i am a newbie when it comes to hardcore mods.

Any ways what is the three angle valve job i keep seeing posted and what are its benefeits? Tank you berry berry much Tom 8)

 

[rbohm]

8) the best shape for a valve seat for maximum flow is a bull nose or rounded shape. the closer you get to that shape the better the airflow over the valve seat. if you look at the valve seats as they come from the factory you will find the seats are quite wide. a 3 angle valve job does two things; 1: it reduces the width of the seat, and 2: it smooths out the airflow over the seat. how does it do this? you use 3 angles, 30, 45, and 60-75 degrees. the 45 is for the valve seat itself, the 30 smooths out air flow into the chamber as it leaves the seat, and the 60-75 smooths out airflow as it approaches the seat. the more angles you use, the smoother the airflow over the seat, but the more often you need to dress the seats for optimum performance. a 3 angle valve job works for the street. any more than that is a waste of time.

 

[mugsy]

Another question: are the three angles on the valve, the valve seat or both?

 

[rbohm]

8) generally just the seat itself, but often times racers put a second angle on the valve itself to smooth out air flow over the valve.