I know that 3 angle are supposed to be the best but does it really matter? I know a guy that can do a really quality 2 angle for 50 bucks less than anyone doing a three angle, how much horse power comes from a 3? thanks
I'll assume you are building your heads to flow better than stock...
Most machine shops these days have a 3-angle valve job as their "basic" grind. The "better" valve job is one using a tool that actually makes more of a radius with about 8 cuts (can't remember the name).
I'd spend the extra $50 and get the three angle job. The heads will flow much better.
A modern valve job is done with a carbide bit that cuts all three angles at once.
The guy trying to sell a two angle job is using stones to grind the seat, ancient history.
The only way to do a valve job is with three angles. The 45 degree seat angle is sized and positioned by the 60 degree throat and 30 degree top angle.
Anybody trying to sell a two angle job is a moron.
If you are just having a set of heads cleaned up the stones work just fine. They mostly grind the carbon off the seats and don't take much of any material off unless you bear down on them. If you have some brand new bare heads, are installing new hard seats or installing oversized valves you would want to have a full 3 angle job done.