Briggs 12J707-1753-E1
What I have appears to be a leaky intake valve seat. It not loose that I can tell but the leakdown indicates a leaky intake. Resurfaced valve and seat using valve grinding compound and also set valve clearance which cure part of the problem. Compression went from 30 to 45 psi after I did the resurfacing of both valves but the leakdown still indicates leaky intake and the only I can think of right now is a valve seat leaking around its outside mating surface.
The service manual talks about pinging in a loose new valve seat and wondering if this would work with the old seat that appears to leaking.
Now the history of this engine is that it is used in very harsh conditions at a nursery. They have already ran it without oil twice, warp the head from overheating due lack of air flow, and broke several pull ropes all in the last 6 months. When it came this week it would not start with the operator barely able pull the engine over. What I found was oil that is as thick as 90w gear oil, another blown heat gasket and this intake leak. Once I got that thick goo was clean out of the engine at it now will pull through; although, it still feel tight. For what this engine been through the cylinder is a lot better shape on this 98 than the 2013 that they also brought in running rough.
I feel just like wringing their necks some days.