ok im getting ready to get my heads ported out but in order to do that i need to get a valve job done. now i heard there are 2 kinds of valve jobs, a regular and a competition. now what kinda performance improvement can i see out of the competition? they said the would do a three angle cut, and if i do do this then when i port my heads, what size flow should i get? i am planning on getting my intake manifold proted too so if anyone has any ideas on what size flow i should do that too then please give advice.

 

well, thats pretty open ended, but here's what i have heard before.
3 angle valve job about 15 hp alone. polishing the stock designed head gets you about another 20-25 and porting is very differentiated.

 

Well a standard VJ (valve job) can have a wide seat on it... which means the place where the valve touches the head.. This is not really good for flow but good for long life. You want to find a balance of great flow and something that will live a long time. Usually a "competition" valve job will have 3,4,5 or more angles in it and might have some backcut on the valve and some blending done into the port....

Robert Yates said that a VJ is half of a cylinder head and it really is... gotta do a good VJ to get good numbers.

bret

 

A regular VJ is 3-angles. A comp VJ should be a minimum 5-angle, we do what is called a radius valve job, there are no angles, just a smooth transition, with a backcut the flowbench shows a 30% improvement.

As said above the seat width and placement is a big part of this too, this depends on how much spring pressure there is and how long you wnt the VJ to last....Flow vs. longevity.

 

well in that case then is it a good idea to get the competition valve job done? and if not then what kinda job should i get done then. cause i want to get the most power out of these heads as possible. and if u guys can give me some advice then that would help out alot. also what kinda porting should i get on my intake manifold?

 

i sure hope you get the portwork done before the valva job!
3-angle is common
5-angle if you are all out racing to benefit from it.