Usually locktited in, you need to use a stud remover and its best left to a professional head shop. Whats wrong with it? stripped? Its very easy to wind the threads out of the head as well leading to more issues and requiring inserts to be fitted.
there is not enough room to get a stud remover on these. I'm inclined to think they are pressed in
and the only way to remove them is weld a a slide hammer on to them and heat the head, Problem with
that is I dont think those little ball sockets are available, they dont seem to show up on parts lists that I've seen
I would assume the threaded type have some evidence of a tightening technique on the outside.
Mine dont have anything that would suggest that they are threaded in, I wouldnt care destroying them if
new ones were available.
Well I got up early and made a tool to attempt to remove them, I can definitely say they are not screwed
in but pressed in with a good interference fit. I ground 2 flats on the side of the tappet socket (for want of a better term)
and my tool with same diameter 13mm bore with 2 grub screws at about 110 degrees apart because its not possible to grind or get an allen key with more than about 110 degrees apart, A slide hammer on the other end of the tool with about a 1kg weight (slide hammer) and heat the head very very hot and it came out to be used again. I tried to post a pic of the tool etc but my file is to big. will try to make it smaller. I doubt any are screwed in. so i maybe on a winner but will still inquire at the eng recond shop .