Thermactor question

The holes on the back of the heads for the smog tubes (d3ve heads) Can they be plugged with a small brass plug or something? Idea on size? Or the hole threaded and a bolt put in there?

Scotty's (The Mad Porter) site has verry good instructions on how to block and plug them.It maybe one of his free tech tips on his site,check it out.

Alternatively, you can get a foot (or so) of 7/16 steel/brass rod, cut 2 pieces 1 inch long and 2 pieces 5 inches long. Drive the short piece in one end till it blocks the drilled hole then drive the long piece in the other end to do the same. NOTE: you'll most likely have to clean the passage first. AND, NO, 1 long piece will(almost) never work as the passage is drilled from both ends and is mismatched in the middle.