So long story short, working on an aveo that someone else put a head on, hasn't ran since, brought to me expecting it was out of time. Got everything apart, crank mark is lined up, definitely out of time probably 3-4 teeth. What's getting me, I have the locking tool in the back of the cams, but the timing marks on the gears do not line up. Is this similar to the old Fords where as long as the back in timed correctly then your good? Or did previous person screw up the cam gears? Are they keyed?