Quote Originally Posted by discorevy View Post
The factory heads have a screw in plug in the exhaust side to avoid the likelihood of it coming out due to the potential heat differential on that side


Edit: The usual core plugs are just fillers from the casting process, not anything to do with freezing, even if some refer to them as "freeze plugs"
Or Frost plugs. Funny how such a simple thing can be so complicated by a naming process. Welch plugs is what I always called them. I thought they were to facilitate the removal of the casting sand.