On a new head and new valves I purchased for my 190sl, the valve seats were not backed off so I sent it to a local machine shop. My concern is whether there was enough material removed to keep the edges of the seat on the valve from contacting the seat in the head. The photo is not the best in the world, but when I laped the valve in, there appears to be only .1 to .2 mm that is not contacting on the outer edge. Is this enough or should the seats be backed off further?

Thanks - Walt Puryear

Attached Thumbnails