The story go,s on . After replacing the cylinder head and getting it running cleanly i noticed the oil pressure light on at idle. I tested the pressure with a gauge and found it near non existent at idle and only abut 14psi at full revs.
After some internet searches on what the pressure should be , Around 24 to 37psi , I found that these engine suffer from the plug in the end of the camshaft coming out . The drilling is blanked off with a aluminium plug which come out with heat and time.
I stripped out the front end of the tractor and got to the timing cover. After dropping the front of the chassis down . by undoing 7 of the 8 bolts ether side it swings down. Removing the timing cover there was a hole in the end of the cam. Making sure to clean up the swarf tapped the end of the cam, Put a steel thread in and welded it home .Will report on the effects after reassembly.