Conan,
Cam durations are given in two specifications, total duration and 0.050 lift duration. The total duration spec also varies from manufacturer to manufacturer, with duration starting between 0.000" to 0.006" lift.
Total duration: Usually between 240 and 270 up to about 296
0.050 duration: Usually between 170 and 220 up to about 238.
So that marine cam with a total duration of 260 may have a 0.050 duration of approximately 204 to 212.
