Make sure that the stop rod (black color L rod) is slightly shorter than the ext bar and socket as shown below. Otherwise the socket will not sit at the bottom of the cylinder head bolt properly.
The stop rod can be placed outside of the cylinder head wall for support or it could be placed inside whichever is convenient.
This tool is typically attached to a 9½ inch ext rod and a ratchet wrench of 200Nm or more of torque capability.
