hi im new to this site i have a 2.2 astra bertone im going to change the valve stem seals as it smokes abit when i put my foot down onls smokes at high revs tho so i thort might as wel do the camchain as the same time as it has 79k on the clock and have no idiea if its ever been done had the rocker cover off and it looks new and no play at all but already got the new chain so going to change it anyway any adivce that anyboady could give would be great thanks cheers..