Small Engines (Lawn Mowers, etc.): 20 hp Intek Ohv series 407700 Valve/pushod adjust, scott palmer, rocker arm

Question
Marc,
Pulled head, had valves ground and seated,guides and all inspected and look fine. After reinstalling, engine does not start, just backfires. when setting the gap .006,this is between the rocker and top of valve spring,correct? The machinist sets the actual valve gap at the seat,correct? As I understand,there is no timing adjustment,except when setting the flywheel?
Also I noticed, when rotating the flywheel by hand and watching the valves open and close, the left exhaust and right intake opens/closes together, where as the Right exhaust opens/closes then left intake opens/closes,knowing this is set by the cam,i assume this indicative of twin cylinder, if not please advise.

Thank You,

Scott Palmer

Answer
The adjustment for the tappet clearance is between the end of the rocker arm and the top of the valve stem.  Timing on this engine is achieved by, first, lining up the crankshaft and camshaft marks (if engine never apart, this can't change.) and second is the flywheel key and relationship of position of magnets on flywheel to the ignition armature.  You are correct, the movement of the valves is dictated by the camshaft.  If you have everything set correctly and the problem still exists, let me know what you find.  Hope this helps.