have a 11hp briggs and stratton vertical shaft engine that is about 30 years old. In order to check valve clearance does the piston have to be at TDC on compression or 1/4 past TDC. Also, does it matter which way you turn the engine(clockwise or counterclockwise) when you bring the piston to TDC. On the intake valve I get a different valve lash reading if turn the engine counterclockwise or clockwise. However, the exhaust valve reading is the same no matter which way I turn the engine. Could the camshaft lobe be that worn! This flathead on an old craftsman is puzzling. Any help would be appreciated