[Walt Fricke]

Bob

Nice pictures. Wish I coult get my modest camera to focus through a magnifying glass! If I could, I'd supply shots of some random valve stem tips. Not a scientific sample, just what is sitting on my desk. None look convex. From memory, none of my elephant feet have been concave, either.

Others, and some certainly have a lot more experience than I do, may have seen cupping of the elephant foot, or of the tip of the valve stem. Your motorcycle engine being one example. But I never have with my 911 motors. I've had an elephant foot ball tip break off, and had a couple bend at the waist, all due to overrevs. Otherwise, anything that will screw out OK I have not hesitated to reuse, and have not gotten myself in trouble with this cavalier attitude. The valve tips I looked at look fine, despite fairly high mileage on some. Only ones which look beat up came from engines which blew up, as evidenced by dents on the valve head faces. And those don't even look bad - nothing you couldn't true with a valve grinder.

Maybe on some engines this is an issue. Not on my 911s not reved over 8,000 rpm, anyway.

There are lots of things one can worry about in life. Porsche 911 valve lash should not be one of them. Feeler gauge works just fine. Factory says to use it, which should say something.

But for those who are inclined to fret, there is the back of the cam method. And one can just set up a dial indicator and do it that way. Both would take care of any concavity issues.

Walt Fricke