Awesome, now I can reference against this for later use......
.. and if you're in any doubt, valve 'keepers' are collets as in a 'collet' chuck, if you're reading on this side of the Atlantic.
Good and exhaustive writeup there, but it would take me most of that 2 hours to cut 8 valves in properly
for better pictures, copy the image location top a new window and remove the .thumb