I tore into it

I picked up head gaskets this afternoon and tore into the flat head Briggs. I backed the mower up on the ramps and noticed a cooler exhaust pipe so I started on that side. I pulled the valve cover and lo-and-behold, there was 3/16 inch of valve lash on the exhaust valve! Pulled the head and the valve seat was out. Sitting cockeyed in the bore but all undamaged. I pulled both of the valves and they both looked good as well as the seats so I peened the exhaust seat back in. I figure if it stays I have done well, if it doesn't then I will find plan B. The lash was a little low on both of the valves on that side so I used 100 grit sandpaper to run them to the upper end of the tolerance. Tomorrow I will put the spring keepers on and check the other side. I have to double check the tinwork an make sure that side won't be running hotter than it should. That will only cause trouble again fast.

I am shocked that it ran as well as it did. I mowed all summer last year with these symptoms! They are kind of like 8N Ford and VW engines. They can run forever with bubblegum repairs and will be running long after they shouldn't. We will see what it does for the engine. It can only help!

I set my valves toward the high end of clearance so as not having them open longer that they have to.
I would rather hear a little valve chatter knowing they are closing good, and not staying partially open.