Yeah the oil issue I will come across when I take the crank out completely. I would say it would have muck in it and this is why it wasn't oiling properly.

I have also found that the cheap torque wrench I was using was terribly inaccurate so I'm angry with that. SO this explains why it was so tight when I first started it up.

The knocking is a worry though. It was almost as if the cranks shafts (where the conrods bolt to) have been machined down. Although I am certain the previous bearings are excactly the same thickness.

It has to be the gudgeon pins, but it's very rare to have all four wear out in the one instance.

This is so strange.

I will strip the block, clean the crank double check all clearances ensure the bearings are okay and hopefully then there will be some positive results.

It would just be so helpful if anyone has had the same experience and could shed some light.

There are no short-cuts I suppose.

Thanks to all anyway for the input.