To answer the op's question -
Valve guides are the metal sleeve that sits in the head that the valve stems slide through.
Valve stem oil seals are a rubber component that slides down the valve stem and sits on top of the valve guide to stop oil from the rocker assembly side of the head seeping down into the cylinder.
There are two designs on valve stem oil deals that I know of. The older simple o-ring or the newer top hat style.
Hope this helps
Steve.
If I could take a little liberty and add to your post here monkey;-
If the guides are worn or out of spec, they'll need to be replaced.
Following guide replacement, the seats should be re-cut. The reason for re-cutting them is the new guide centres may not be the same as the old and with worn guides, it's likely they have also worn the seats off centre too.
If the Seats are re-cut, it would also be wise to re-cut the valves themselves.
As others have suggested, fit valve guide seals to all 8 guides, The 'hat' type are usually streets ahead of the O ring types.
In regards to valve Guides, there are standard Cast Iron ones available as well as Bronze types, for street use, I would suggest Cast Iron. The Bronze ones are good but much less forgiving and can be 'fussy'.
