Originally Posted by vinniekq2
ap sometimes you make very good posts,sometimes you dont. 300 "advertised" and since when does time( duration) become not effective with any head? show the math,,,,
"advertised" duration is completely meaningless since it is not the same EVEN WITHIN THE SAME CAM COMPANY.
As for the math, on those heads you need to notice a few points. Flow, compression, and choke. Even assuming those 160cc heads were heavily ported and taken out to 180cc's you'll be choked around 5800 RPM in the pushrod pinch, assuming you flow enough to make power at that point (225cfm would be adequate and relatively easy to hit) and you have enough compression to make power at that RPM (9.5:1 is about right for that RPM and those chambers) then to make the most average power at those RPM you need to match the duration.
Since you're not working with a restricted intake nor a really good exhaust a 220-225 duration would provide about the duration you need for that RPM and power. With a good thorough job you can easily get over 400hp.
There is more definite math involved than these generalities but I don't feel like putting the effort forth to show it. A great basic website for related calculators though is Wallace Racing.