lol. I checked pdf manual , no help. Then I checked a briggs repair CD I bought way back. One of the reasons I still run an XP computer. It says early production 28 ohv used a 2 piece intake valve stem seal. see figure 20. , but there's no figure 20. Then says current production use a 1 piece seal , see figure 19 which actually exists.
on the early the seal is in the cup and cup has flange that valve spring seats against head. On the one piece what actually holds the seal from moving up with the valve stem?
edit: ok found this
viewtopic.php?f=3&t=3074&p=21921&hilit=intake+seal#p21921I even posted. I guess later production head had recess for the seal body.
so in that case is the old seal available? or would you be looking at a new head if you wrecked the seal?