Small Engines (Lawn Mowers, etc.): Engine Overhaul, installing, cam

Question
Briggs and Stratton Engine 28R707, type 1120E1, code 03052820.  I am overhauling this engine, however, I have a problem.  Two question:  How do you set the timing? Second, does the values need to be set a proper way?
Thanks

Answer
There should be a dot or other mark on the cam gear and the crank gear.  Just line these up to set the cam timing.  For the ignition timing, this is mainly controlled by the flywheel key and is non-adjustable except for the use of offset keys for performance purposes.  You can play with the ignition timing slightly by altering the air gap of the coil to the flywheel.  But generally it's best to just set the coil to spec.

For the valves, they seldom need any adjustment in an L-head engine like you have.  The clearance between valve stem and lifter when both valves are closed is from .005" and .007" on the intake and .009" and .011" on the exhaust.  If you're using the original valves and didn't cut new seats, there probably won't need to be any adjusting, but check anyway.  If you did cut new seats, then you may need to adjust the valves a little.  You do this by grinding off material from the valve stem where it contacts the lifter a little at a time.  Usually just lapping the valves won't lead to needing to doing this.