strange noise
 

76 911 2.7L
Sometimes when I start my car after sitting for 1 hour or so it iddles very rough and when I accelerate a strong humming sound comes from the motor compartment, but only when the car is running, if I accelerate the car at iddle speed there is no humming.
Any help is appreciated.
tks in advance....

I had a '73 with a 2.7 CIS. Usually the cold start problems are results of a "lazy" warm-up regulator.

There is also something about an idle lever in between the two seats. Anyways, its been so long since I had experience with the CIS, I forget. My dad has an 80SC with CIS as well. He has had the same problem. He also replaced the warm-up regulator three times. Each time was with a "known good" Finally, he bought one new. This did the trick.

I don't know about a humming. That seems rather vague. Perhaps the belts are too tight?

Good luck!
Nick