I Instro84 USAF retired Joined Jul 17, 2005 Aug 11, 2017 #1 need to clean up the head bolt hole on a block what size tap do i need to get? thanx
ek02 Well-Known Member Joined Jan 31, 2008 Aug 11, 2017 #2 7/16-14. Best to use a thread chaser, not a tap unless the threads are damaged.