in order to run a 1/4" mpt tap into bottom of SBC (5.0) block I had to remove the manifolds and risers and discovered the flappers on starboard side were not closing and one was broken. What caused this condition and what is procedure to replace. Also some one mentioned that I should use "plastic" pipe plug at bottom of block. Is this better than brass plug I removed. Should I use teflon tape or pipe dope or dry on plugs
