Don't understand cams
I think i read somewheres that chry figure there cams duration and overlap at .002 lift not 0. them you have comp that will give some advertised spec's. But they do them at .006"
I realize that chry is the only one that give spec's strictly by advertise and the standard has become @.050.
I don't think anyone every gave advertised at .000" lift; it is too vague to find on the cam lobe in the measurement process. It is common to give advertised duration as well as .050" duration from just about everyone. Now, there are quite a variety of lifts at which advertised durations are measured; I've seen .004" and .006" and some larger numbers for some solids.
The .050" lift standard is just one standard point of measurement; it surely does not tell the whole story, as you and others have pointed out. I'd want to know both; it gives some idea on the ramp shapes.
BTW, so your cam card does NOT have the advertised valve timing events? With the .050" and advertised durations, one thing you could do is:
- figure the difference between the 2 numbers for intake and exhaust
- divide those numbers in half
- add those to the .050" exhaust closure angle and subtract from the .050" intake opening angle to get some 'advertised' valve event angles
- figure overlap from that.
That process does not account for asymmetrical lobe shapes, but will get you close.