Originally Posted by chevykid90
i couldn't find anyone around here that had a set of closed chamber heads that were in my price range. but in my numbers book these heads had the smallest chamber size with 112cc. i am not going into having bigger valves put in, but will porting them give me any significant gains?
If you can do it yourself, there's something to be gained in many cases, by smoothing the transition from where the factory tooling cut the last angle into the port. There is almost always going to be a "lip" that interferes w/the flow, as well as the usual casting flash and irregularities that occur as a matter of course in mass produced iron castings like these heads.
There's not as much to be gained by porting the runners, the "low-lying fruit" is said to be the bowl. A three angle valve job done correctly will be an enhancement that will likely be as much of a gain as anything else you might do, so be sure and have that done.
A 30º back cut done on the valves is also helpful, and doesn't cost a fortune to have done.
There are reduced diameter valves available for your BBC. The entire stem isn't reduced- just the portion that's in the bowl area of the head. I've not used them, and I have heard conflicting reports of how much is gained by using them. If your
research shows them to be beneficial- and IF valve replacement is needed anyway- they'd be an option worth considering.