This custom tap is made specifically for chasing head fastener threads in the Subaru EJ engine blocks.  This tap is a bottoming tap, which will go all the way to the bottom of the threads.  It is also extra long, so your do not have clearance issues with your tap holder.    Our cleanout taps are custom sized per application, as not all block threads are equal.   These taps will not pull any metal out of the existing threads, and clean and debur for a nice refinished thread.
 
It is recommended to clean main and head fastener threads during any engine rebuild.   We also offer the main fastener thread cleanout tap as well.