[MBEngineering]

HI Vincent 911

"After more than 5 minutes a noise appears. It was like 2 metallic parts hitting each other. The noise started to increase"

have a look at your No'5 rocker's , poss the intake adjusting swivel is dry!!,
I usually fit the lower rocker covers and then flood the rocker gear and cam with oil to stop that noise, also pump oil down the cam feed in the cam box and check the spray bar is working?

regards mike