Her's some links to my site with the information that may help you understand more:
Carb CFM calculator for Demon Carbs
http://www.4secondsflat.com/Carb_CFM_Calculator.html
Racer Bown cam specs and combination suggestions:
http://www.4secondsflat.com/Racer_Brown_Cam_Specs.html
You may find this article of interest also:
http://www.4secondsflat.com/Cam_Design.html