Ran into problems replacing camshafts after pad replacement

[Anker]

Originally Posted by JFP in PA

Because when the engine truly rotates backwards, the valve timing will result in instant piston to valve contact; even rotating by hand, the mechanical advantage is sufficient to bend valves. When you back off of WOT, the engine is still rotating clockwise; the only way to get it to rotate counter clockwise is by someone turning the crank backwards.

Or spinning 180 degrees without both feet in! Can happen on track and in autocross. Important to do full brake and full clutch immediately when you spin, otherwise the car will pull the engine backwards when you roll backwards after the 180.