Measuring PP port timing

[RICE RACING]

Apex seal leading edge for opening (bottom extremity of the port, typically flat edge or bevel if it got a big one on it) & apex seal trailing edge for closing (on the outer apex *most are rounded* or tapered end to end at the middle of the port of the closing edge or bevel if its got a large one on it), obviously on the one chamber

So round port, flat open round close or square port flat bottom flat top or tapered it does not matter, you just pick the extreme ends and that defines your opening timing and closing timing on peripheral ports port volume to timing relationship is LARGE so a fraction of a degree either way due to a large bevel (rounded edges to the rotor housing surface is not that critical) just keep both the same. A flash light (pen light) helps you pick this rather than naked eye.