Okay, so it's up and running, so much quieter, didn't realise how noisy it actually was. No rattles what so ever.............However, I believe there is an air leak somewhere on the intake manifold as the the idle speed has increased. When I first started it there was no problem it idled beautifully, unfortunately I'd forgotten to refit a couple of hose clips to the thermostat housing and I had to remove the upper inlet manifold to get to them. After refitting everything the idle speed was a bit too high and erratic. I have another one so I'll swap them and see what happens. The other thing it could be is the idle body on top of the manifold. I'm fairly convinced it's an air leak though.