3 angle valve job

[jgar]

So I see some of you guys have 3 angle valve jobs in your sig.
What do you gain? Is this some thing that is worth while to do if you have to rebuild the head?

[xtreme762]

It allows the valve to seal faster and more tightly. It also increases port turbulence, which increases air speed, allowing more air into the mix.

Normally when you do a 3 angle, you'll want to port and polish as well to get the most out of it.

Good Luck

[400exmxracer]

Not to hijack your thread, but I've been wondering what I will gain as well. I know what it does, I just want to know how much of a difference it will make. This is what I have already

02 400ex
426 wiseco 11/1
Stage 2 hotcam
Wiseco crank
Mildly Ported and polished head
Stage 3 amr cdi
Fmf powerbomb header
Big gun EVO r slip on
Fcr 39mm carb
Dirt digger clutch
Hinson clutch basket
Stock gearing(for now)
Open air box
I'm probly forgetting stuff

[bcleveland]

Originally posted by xtreme762
It allows the valve to seal faster and more tightly. It also increases port turbulence, which increases air speed, allowing more air into the mix.

Normally when you do a 3 angle, you'll want to port and polish as well to get the most out of it.

Good Luck
Bud I hate to say it but most of what you said is wrong. It doesnt allow the valve to seal faster or tighter. It gives a radius for the air to flow over when coming over the seat. Instead of sharp angles. It gives more flow and less turbulence. It can increase air speed better known as port velocity. You want just enough turbulence in a port to keep the air fuel mixed. Combustion chamber turbulence is a good thing you want to get that fuel air mixture swirling a nd tumbleing. But there are rite and wrong ways to do this and the only way to check for sure is to pull the head and read the burn pattern on top of the piston.

[Honda5]

^ Exactly

[jgar]

I started to read up on it last night. Seems like a flow thing. So what a burn pattern and how read it?
Just trying to learn...

[ds268]

Multi-angle valve seat cuts allow better flow plain and simple. The angles and widths of the angle cuts are critical in achieving max flow potential. It has nothing to do with the how tightly or quickly the valve closes -- that's the cam profile and springs. Ideally, you don't want any turbulance in the port. Turbulance creates dead spots and decreases port velocity. This is generally why porting out a head without understanding how or why will cause a power loss from a turbulant port. All mixture should occur within the chamber.

So is it worth it? If the valves need to be replaced and a valve job is required then absolutely. However, this isn't something that will make a noticeable gain like adding a higher compression piston or cam.