You are probably in uncharted territory unless you can find manufacturer specs telling how far to go. Or you can do it the old fashioned way trial and error. Assemble the engine incl valves so they operate correctly and in time. Go to a craft store and find some modeling clay. Stick a small amount of clay into the head where the valve may interfere with the head. After sticking the clay to the head, use some #105 motor assy grease on the head of the valve so the clay will not stick to it. Then with an already settled head gasket install the head and torque to correct spec. CArefully and slowly turn the engine over at least 1 full turn (360 degrees). Then remove the head. If you are careful you can now measure the thickness of the clay where mashed in close proximity to the head, this tells you how much clearance you have. From here you just have to remove small amounts of head surface till you get the desired height. I would leave at least .015 final clearance. Remember there are many things that will change this valve to piston interference. 1. head gasket thickness 2. head thickness 3. block deck height 4. valve lift (lobe on cam) 5. valve seat grinding 6. valve face grinding.
Small engines are neat to experiment with because you can get away with things you could not on a multiple cyl engine. Proceed slowly take your time and you will probably even learn something by it.
Small engines are neat to experiment with because you can get away with things you could not on a multiple cyl engine. Proceed slowly take your time and you will probably even learn something by it.
