the cheap one at Harbor freight will not go in the spark plug hole. That camera has a .625 probe diameter. Now the 300.00 dollar one will go inside the Rockets 12mm spark plug hole and works great you can go thru the top of the head where the cam gears are and see down under the crank gear.
looks like this
Takes video also and will take a memory chip microphone and head phones. has digital zoom and control of the amount of light.
you can even check the APE manual tensioner to make sure you have it in the right location. Or if not you will find out soon enough!!!
The screen produces a much clearer view then still photos. as the light reflects and fuzzes the picture.