Thanks guy's. I stripped her down for inspection and it appears that the camshaft timing actuators had blocked screens (drivers side was the worst) The timing chains have a little wear by the the look of the tensioner, but the the marks are all spot on. I have since seen other LY7's with the same noise which were either the camshaft actuators or restricted pick up/faulty o-ring on the pick up pipe or oil pump not supplying enough pressure to the camshaft actuators. I ordered a few bits and have been away at work for the last 4 weeks. Will drop sump and check pick up and clean, replacing all 4 actuators and oil pump for shits and giggles. Going to give it a good clean top to bottom while I'm there as it is a bit sludgy. It had plenty of oil and I ran it with the rocker covers off to help further diagnosis, noise seemed to be coming from the camshaft advance assembly on the drivers side. I think that this was brought on by me adding an oil conditioner to the engine which increased the oil viscosity and helped pick up **** to block the screens. I know that I can get a replacement engine cheap and easy enough but I want to try this first to satisfy my curiosity. Will be home in a week to get started back on it, will make sure that I keep ya's updated
