[mustangurl00]

How much hp can be gained from a 5 angle valve job? how will the valve job be affected by porting and polishing heads?

[Codeman]

a few hp. not a whole lot. the most you will gain will be through the combination of the valve job and the porting and polishing along with some bowl work. Most places do at least a 3 angle valve job or at least that is what they call it. Generally when you do a valve job you do a 44 or 46 degree seat cut depending on the manufacturer and what they cut the valve to. You do this till the seat is round and clean. You then lap the valve and check to see where it is riding. They then cut the other two cuts to get the correct location on the valve face where the valve should be riding and the the correct seat width.

I don't think that a 5 angle valve job is even worth it. I think that it is almost a con to get people's money. Heck I don't think a 3 angle valve job is worth it. Since technically a normal valve job is a 3 angle job if the engine builder is checking their work and ensuring that your valve face is riding at the right height on the seat and making sure the seat is the correct width according to the specs.