Hmmm...just plugged the smog ports on the heads of my 225 OF V6. Bought some 1/2" - 13 x 1/2" stainless set screws. Smeared 'em with some copper Never-Sneeze and cranked 'em in. Worked and looks great The fun part of the project was removing the tube that runs inside the exhaust port up to the back of the exhaust valve. Those suckers did NOT want to come out.