Mike, and others
Be careful in interpreting cam specs. I am trying to understand the document and cam specs. I see the document notes the SV cam inlet is Open at 29 BTDC and closes 63 ABDC. Duration is then 272 ( 29+63+180). These are the same specs noted in the WSM for the 1725 But it is unclear to me what is considered "Open" or "Closed". (Also lift is not specified).
I have installed a KB grind cam in my 1725. The specs I have from Delta for this cam shows Open at 5.4 BTDC and Closed at 37 ABDC, with duration then 222.2. This would imply that the KB grind has less duration and is a milder cam than stock. (lift is specified as 0.408", which i assume is same as stock)
BUT, if I look at the details of the Delta cam specs, I can see that "Open" and "Closed" are considered as the point where the lift is 0.050". In fact, there is a statement "events rated at 0.050" tappet lift". Furthermore, if I look at the table included in the Delta specs I can see that if I assume the lift point is considered as 0.006", then the Open and Closed points would be 46.3 BTDC and 71.1 ABDC, for a duration of 297.4. More duration than the stock cam. Without stating the definition of the lift point, I don't see how to compare profiles.
In reading a wiki article on Camshafts I see that it is common to rate open and closed at several different lift point, with 0.002", 0.006", 0.020" 0,050" and 0.200" being common. Depending on which lift point is used will give you different insight into low end torque, high end, peak power, etc.
So without lift point definitions in these comparisons I suspect this article has little value.
I am very happy with the performance of the KB grind in my 1725, bored, stroked, and Vizarded to about 1820, with CR close to stock 9.2:1
Tom