What exactly does a 3 angle or 5 angle valve job do? Im not to firmiliar with headwork, I just usually buy built heads.(i.e. my SBC) Is there a significant HP gain, is it for durability, flow, etc.?
Failure is not failure if you learn from it
Multi angle valve jobs smooth the transition of the air / fuel and exhaust gas flow around the valves and valve seats for increased velocity. This increased velocity helps develop more torque and to a lesser extent, horsepower. The more angles, generally, the smother transition. The best is a continuous radius, which just rounds the seat, for the smoothest transition. These work best with a ported head, but will work with a stock head. The stock head already comes with a multi-angle valve seat, but wear down over time. A good machine shop can put a better valve job than the stock head comes with. The valve job alone isn't worth pulling the head for, but if you have to do work on the head, then it's worth the few extra $ to do over a standard valve job.
A ‘multi-angled valve job’, typically 3 or 4 angles will result in smoother transition for the air and greatly enhance flow, while maintaining adequate valve seating area for the necessary dissipation of combustion heat. This precision process is considered standard practice in performance tuning shops.
Multi-angled valve seats are one improvement that does not require the trial and error ‘art’ that is found in cylinder head porting. Requesting a 3-angle valve job should be considered the minimum that you would ask from your machine shop. Typical 3-angle valve jobs include an angle cut on either side of the actual sealing area of the valve seat. The high accuracy required of this technique means that the seat area is kept to a minimum (often less than half of the original seat area). The net result is that the gasses are encouraged, or funneled, through the valve-to-seat opening. The flow increase is dramatic. The intake seat width is typically about .040” while the exhaust is kept a little wider (.050”) to allow for better heat dissipation. It is critical that the corresponding cuts in the valve seats be matched and thus it is important not to switch valves
for lamens terms, better air flow into the combustion chamber.
SON OF A BITCH!!!
I just typed up all this @!#$ for you to read and my window disapeared... now I have to start over.
ok heres a lazy version....
When you do a bunch of port work and stuff it won't do much if the the valve/seats aren't doing what they should. The point of a multi angle valve job is to help with flow slightly by having less restiction intothe cumbustion chamber and and helps performance by making sure when the valve closes it actually seals how it should. When going all out on port work and valve train its deffinetly advised to go with a multi angle valve job.
- Multi Angle Intake Seats/Valves -
- 45* angle on the intake valve face
- 30* undercut intake valve
- 45* intake valve seat
- 30* top cut intake valve seat
- 60* bottom cut intake seat
- Multi Angle Exhaust Seats/Valves -
- 45* angle on the exhaust valve face
- 30* undercut on exhaust valve
- 45* exhaust valve seat
- 30* top cut
- radius (blend) departure
