Yes, it can be off by a couple of teeth and still run. In fact, the Ford 2.3L engine from the late 70s had to have the crank timing advanced by 3 teeth in order to run after changing the belt.
Because nobody is perfect and everyone makes mistakes. They will usually test the ignition timing after assembly, but if the cam timing is off, it won't show up as readily.
Monday, November 21st, 2011 AT 3:22 AM