Arsenic is present in the environment as a naturally occurring substance or as a result of contamination from human activity. It is found in water, air, food, and soil in organic and inorganic forms.
At first glance, it may seem difficult to explain. A difference in the lobe separation angles (LSA) of the cams can explain the difference. LSA is the Lobe Separation Angle or the number of degrees between the intake and exhaust lobe centerlines. The LSA has a direct relationship to amount of overlap on a cam.
Talk about airplanes! At last count, there are 39 (and growing) FAA certificated S-LSA (special light sport aircraft). These are factory-built ready to fly airplanes. If you can't afford a factory-built LSA, consider buying an E-LSA kit (experimental LSA - up to 99% complete).