I have a warning
o not turn backwards or you will bend the valves.Turn the crank as you are tightening a bolt.You do not need a special tool and put the timing marks in the right spot before taking off the timing chain.Replace the timing chain at the same time if needed with a new tensioner.Use 2 5/16 bolts to hold the top gears in place,there is a hole for them and pull them out after setting the timing marks.