are you sure that a duration of 264 means that the inlet valve is open for 264 degrees out of one cam rotation? that's 528 degress out of the 720 degres of 2 crank revolutions? how can you fit in 4 strokes if the inlet valve is open for that long?

maybe it means 264 degrees of one crank rotation (so 132 degrees of cam rotation)?

i don't know for sure, i'm just trying to learn along with you.

maybe this diagram, found by Gareth T on this post helps?