With the rocker cover on and the car idling, i used a long screwdriver as a stethoscope to listen in on different parts of the engine. It's really amazing how well this trick works. Anyway, i could clearly hear the injectors ticking away by putting the sharp end on one of them, but i dont think that was the noise i was hearing. I did notice however that the noise was far more evident at the front of the rocker cover than the rear.
With the rocker cover off, i could perhaps see why:
On the No. 1 cylinder cam lobe for the inlet, you can clearly see it's worn already. That was a brand new cam no more than 1000 miles ago! The thing that mystifies me still though is that i had this noise before i changed the head/cam/rockers, so perhaps this isn't my problem. The rockers came with the second-hand head that had previously been used with the exact same type of cam that i've used, so there shouldn't have been a problem.
Any ideas or suggestions?
Funnily enough, the car is a little less noisy now, but i changed the injectors and changed from fully synthetic to semi-synthetic oil (Castrol Magnatec) so perhaps they could have contributed to it.
