Small Engines (Lawn Mowers, etc.): Briggs 4.5 Quantum valve timing, piston assembly, crank case

Question
Greetings, finishing up a rebuild and need to know how to set timing? With crank case off and piston assembly at 9 o clock postion, cam gear at 12 o clock. The timing mark on crank gear with piston at TDC is at the 3:00 position. How do I line up the mark on plastic cam gear? I've tried lining mark on crank gear with mark on cam gear but piston is then not TDC and I have no compression? Only one way crank gear fits because of key. When timing marks line up crank at 12:00, cam at 6:00 piston is not at TDC?

Answer
Do you have a plastic cam?  Sometimes the cam timing mark is a drilled hole or indent in the plastic teeth.

I would like up some marks and follow the strokes.  The intake should open on/near the down stroke.  The next up stroke should be the compression.  Coming back down is the power stroke.  As the piston starts to up again the exhaust valve should start to open for the exhaust stroke.

You should also have both valves slightly, very slightly at top dead center on one of the strokes.  This is valve overlap.  All 4 cycle engines exhibit this property.

Let me know if this helps.
Eric