A slighlty noisy clic-clic for my RR/SS motor

Hello everybody,

I bought recently a Bently T1, 1973.
My motor is having a light "clic-clic" noise.
This noise depends on the RPM, but not fully.
I can hear well the noise from inside the car, and much lesser when I
am close to the engine, having the bonnet opened.
My engine does not consume any oil.

Thank you for your help.
Antoine.