Well, I think we'll call it a day there. Ben (SZ-R) kindly came round to my house today with his mate Darren to look at the car and to see if they could diagnose what was still in the engine.
So he fired it up first to see if he could get an indication of where the noise was coming from and told me straight away that it seemed as though it was buggered.
We took out plugs 3&4 and had a nose round with the boroscope. The first one we looked at was #4 and it seems there is a chunk of piston missing. The surface of the piston looks like its taken a beating and there is a 'H' scratch on the top which looks to be the initial point of impact for the screw. Also, there are fragments of metal which have managed to wedge themselves between the sidewall and the piston so it is scratching the inside of the cylinder. So that would mean it would need to be bored etc.
As this is an NA engine, I'm not going to bother with it. This is the 2nd GE engine in 12 months I've been through, I'll get some pics up later for you of pistons 3&4.
Time of death: 12:55pm on Saturday 12th January 2013.