Plugging smog holes on 302 heads

1/4 tap, allen head set screws and a little loctite. Done it a few times on 302's and 308's, works great.

Only thing I would add is that you really should drill the smog ports for the tap first, they're close to 1/4" but not super consistant. Some will probably work ok, others will be smaller and you could end up trying to cut too much metal with the tap. 1/4" x20 by a 1/4" or 3/8" works fine, they don't have to be very long. In fact, I like them shorter so you don't have to worry about tapping very deep, and you know the set screw won't go anywhere.