sometimes my cossie engine makes a tick tick tick etc noise when i rev it or accelerate but it doesnt do it all the time. its coming from the head which is a recon and ported and polished and has now done about 13000 miles. ive recently done an oil and filter change. any ideas? hopefully something simple

 

maybe have 1 or 2 sticky cam followers.

 

sounds like exhaust blow where the manifold meets the head mate?

 

I have to agree fairly common