I will try to give better information, I guess the problem is I do not know what is helpful. The flat edge will rock on the valve when placing it across the top of the valve stems. I do not know how to measure it.
The tractor was very hard to start when pulling it, but ran good when it did finally start. I have no mixing of water and oil, so I believe that the head-gasket was installed correctly, after installing the new rings and liners.
now that you mention it, the oil in the exhaust has got to be diesel. It is thin like diesel, and black from the soot I am assuming.
I will do the valve lash again. One book says .30MM and .40, another book just listing specifications, lists both at .38-.48. I used the .30(.014) and .40(.016) so when I do it again, I will use a little more gap.
thanks