So the story so far.
My engine appears to be a 2nd gen 235 (4 bolts on cam cover, smaller pushrod cover plate.
The "knock" disappears when removing the lead from Piston 6 near the cab
The next step then is to drain the oil, remove the pan and remove the rod cap to view the bearing shells, this will tell me if the bearings are worn and whether they are STD or undersize.
I have ordered some plastiguage from the ebay, will order the shells from the ebay US (nowt on UK ebay) and get some more SAE30 oil and oil pan gasket
A couple more questions if I can, before emabarking on this journey. What torque should the rod bolts/nuts be tightened to? I read mention of 40lb/ft but that seems to be mainly 1st gen 235s are the second gen the same?
google isnt helping with this one.
TIA