Why is ther no formula to figure out port volume?

Rumble, The eddy's are 168-170 cc's as cast and not much room for porting as they get thin. I've went through at the pushrod pinch more than once and just barely started to port the heads. So IMO I would say that you may be able to get them up to about 175-178 cc's with the bowls hogged out. They would work on the 410 CI engine but the upper RPM's would be the limiting factor as to where the hp would actually stop or fall off some.

I ran a set of 452's on my BB that was 404 CI and the heads were 184 cc's and they did ok but I could feel the power fading some at 6,000. The car actually ran the same times shifting at 5,600 rpm's. The heads that I really needed for this engine came out to be 192 cc's. But bracket racing doesn't have to be or need to be the fastest, but the most consistant, so there wasn't any need to change the heads as it was winning races.