Tapping Noise

[roadrunner]

Hi, I have a 500 SEC 1985 & i'm getting a tapping noise from the engine on tickover. You tend not to hear it once the revs pick up but it is slightly there.
Anyone got any ideas?

 

[Myros]

does it come from one side or the other

in time with the engine revs, or in time with some belt- driven ancillary?
Welcome to 20 questions.
What's the mileage, have you had the chain tensioners done at all?