Don't understand cams

273 you are correct, in that I start thinking about what I need as far as HP to achieve the goal. If I need 450 HP in a 3400 pound car to get, say, 11.50's then I have a starting place. Then I look at displacement. Am I going to do it on a 3.313 stroke, or 4.000 stoke? How much bore do I have to work with? The bigga the bedda I always say. Sooooo, if I can get a 4.125 bore, I can take some stroke out, make the rod a bit longer, spin it a bit higher, gear it a bit lower etc.

Once I get that sorted out in my head, I decide how much RPM I need, and can I get enough port to feed the displacement I have and the RPM I need, without a cam that need 300* at .050 and that will at least will idle at 1800 RPM or lower (I threw that in there for the 500 RPM idle in park guys with a shift speed of 7500 RPM lol). Then I start looking at compression ratio. What fuel. Then it's works on the heads and flow them to see if I'm even close to what I think I need. All the time everything except the hard parts are in flux. Things like induction, actual cam timing, final CR and such. Once the valve job is sorted out, and the ports produce enough GOOD air to make power, then I finalize all the other stuff.

It makes sense in my head.

It would be interesting to see how others think their way through a build.