Dare i say it Brian.. But surely the Head has been ruled out by now..
Which leaves the bottom end. Have you put on the oil pressure gauge?
Maybe the oil pump hasnt provided enough pressure and what you are hearing is a worn big end bearing?
Thinking left field... hows the crank pulley? Is there play on the key way? Is the crank pulley bolt tight enough?
Are you using a crank pulley that allows the "special" tool to be fitted so that proper torque can be applied to the bolt?
I am very sympathetic about this build Brian... You will sort it out eventually...
ps... High Tech Cylinder Heads in Malaga..
