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On the last set of heads I had on the Square, the had 60-70K on them when I did a valve job. #3 had been tightening up, and I found the seat had indeed settled into the head, and the valve had mushed into the seat, so that the contact surface on the valve and seat had increased. I guess it was getting ready to break. I still have this valve and could measure it if there is a steadfast spec for stock length. I cant remember if it was a VW valve or Aftermarket.... I may still have used an aftermarket valve in 88 when these head were new. Keith > It is caused by the valve not hitting the seat square when it closes. > And each time, the valve is bent a little micron or so. and then bent > back maybe the next time. At the number of times the valve closes per > minute when our engines are running at highway speeds, the metal starts > to fatigue. As it fatigues, and the seat starts to get hammered. The > valve settles into the seat, and due to the metal fatigue, the valve > eventually breaks if not replaced. > This is one reason I ALWAYS replace the exhaust valves, and the guides > on any head I do, unless when I measure the guides they are found to be > OK.. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~