be careful if you want to remove the knock sensor, i needed 3 days it's like [EDIT] welded on block, and the little space you have to make your moves!!!!! i needed to remove the starter ....... don't try to remove unless you are 100% sure you need it. just a warning.

 

The threads on the sensor have loctite on them. Applying localized heat on the block with cause the loctite to "loosen". Just don't overdue the heat as you might damage the sensor.