Tony,

The Threaded Rings are available under part number 617 017 00 03. There is also a special tool required to pull the pre-chamber out of the head. Sometimes, they can be quite stuck. You might have to make somthing that will engage the pre-chamber threads and pull it upward.

Be sure to clean the area where the pre-chamber seats in the had. I use a film of Anti-Seize Lubricant on the contact areas between chamber and cylinder head and the threaded ring itself.

Torque to about 100 lbs/ft when finished.

I hope this information is helpful...Bert