Engine: like a strange bird noise
 

First : it is not a joke...

Second : the facts

My '73 double carburated 2.0 runs well, but ... when the engine is middle hot, a strange "cui cui" noise comes.

Example: I leave home, I drive about 20 kms, no noise. I stop the engine and 15 minutes later, if I start the engine again I hear a strange "cui cui" noise comes.

It is directely indexed on RPMs. It does not seem to be the clutch. The noise is here when pedal pressed or not. If I rev up the engine, the noise decrease but when I use engine braking, the noise comes back. The noise comes from the impeller aera. Alternator ? Distributor ? Bearings ?

I know that you won't fix the problem without hearing the noise, but may be this happened to somebody ...

I remembered a post awhile back with the same indications. Check it out & maybe you'll have some luck.
http://forums.pelicanparts.com/showthread.php?s=&threadid=88173&highlight=chirpin g+noise
bruce

Lube the distributor cam...where the points make contact...just a "petite" amount of grease will work but dielectric??? grease in purpose made.
Check fan/alternator belt tension
Check sheet metal screws. vibration at idle can cause metal on metal chirp noise.

check the belt alignment and for objects in the fan.

also belt tension.

Hungry newborns in fan housing.