I've searched around with no avail.

 

Search a little harder. It might help to change your search settings to return ''topic titles only.''

Here is a great thread:

https://honda-tech.com/forums/showthread.php?t=1234798

 

Oops, sorry guys.

 

Most factory valve seats are cut at 3 angles. They haven't done 1 angle valve jobs from the factory since the days of leaded fuels and seats that were cut right into the head material. Its very rare that a stock engine would have a 2 angle valve job either. You *must* use 3 angles to get the valve seat to the proper width. A wider seat is not necessarily a better seat. Wide seats transfer heat better but do not seal as well. Most engines use an interference angle from the factory. It improves sealing and allows the valve to 'self-center'. When someone says '3 angle valve job' they are talking about the valve seats only and not the valves. Valve faces are cut at one angle only. 'Back cutting' is something to do with changing the shape of the valve head to change flow, it has nothing to do with the sealing of the valves. The additional 2 angles of a '5 angle' valve job radius the entry to the valve seat and also have nothing to do with sealing either. If someone really does not know what they are doing they will remove the venturi which is made up of the valve seat and the material right below it when doing a 5 angle valve job and will kill velocity past the valve. But this will increase the peak portflow (in cfm) which is good right? Not necessarily. You need to look at flow at all lifts, not just peak cfm.