['75 308 GT4 (Peter)]

Mick, its very difficult to interpret people's descriptions of engine noises, but I can suggest the source could be:

-Whoever did the timing-belt work, did NOT replace the belt tensioners and they could be worn-out, dried-out, etc...

-The lower cam-belt-drive pulley's bearings are a known weak spot as they don't get adequate lubrication (solved on later F.I. and QV cars with sealed cartridge bearings). They don't get serviced by the techs as its a MAJOR task to remove & replace.

-You should also consider the water-pump, the A/C pump and alternator as the sources of the noise too.

Does the noise occur only at that RPM, or at other points (before/after/over a range of points/etc...)?

 

['75 308 GT4 (Peter)]

Mick, you can confirm by listening to the tensioners using a mechanic's stethoscope (like a doctor's 'scope, but instead with just a plain tube on the end).