Strange Engine Noise
 

Hi


I have a 1972 911E with rebuilt 2.4 motor with 36,000 miles on rebuild and carrera chain tensioners and rebuilt MFI pump last fall. Started this car up as the weather warmed up and had a dry day to back it out and let her run for awhile after 2 months sitting idle. Car started right up and ran ok for a few minutes. Then a strange high metallic sound at idle coming from right rear bank? Not every revolution just at random. Dissapear if increase RPM. Sounding almost like something expanding but the sound of engine changes each time this sound was heard. Any ideas???
Thanks James