The performance of the engine doesn't seem to be affected by that. But the noise is so loud that you are not tempted to push hard on the accelerator!
Clearly the noise is syncronised with the opening of the valves. So the noise is clearly comming from the top of the engine. I tested that by putting a flat screwdriver on the valve cover with a piece of clothe and putting my ear on the screwdriver handle. That way you can hear clearly feel the vibration source.
I tried adjusting the valve clearance 2 times and the first time the noise disapear for a week and it came back. I think it is related with that mecanism altought the clearance hasn't change since the last adjustment.
Is there another part of the valve mecanism that can by wear out like the springs or anything you ever heard of?
Don't be affraid to get technical... I'm familiar with mecanical terms
