Hey guys , my engine started whistling last night. Ok, heres what I did, yesterday I pulled my car into the garage just to put new valve covers on becasue my other ones were leaking, they are the late model efi aluminum type. They fit like a glove, I understand I need an oil shield under the pvc ,I didnt put one on, I think I'll have to rip the one of the old valve cover and somehow screw it to the new one, I didnt realize this until I read about it on this site. Anyways I started it up , I let it idle for a while , no oil leaks. Then drove to my friends house and on the way there I hear a loud whistling noise, so when i get there I pop the hood and try to find out where that noise is coming from, I couldnt tell where it was coming from. Today its back in the garage, I pulled the air cleaner , I started it up,I let it run,I had my head near the engine and the sound seems to come from in front of the carb. I put a rag on top of the carb with my hand over it then the engine dies out,then I started it back up and sprayed some carb cleaner around the front of the carb near the idle mix screws and the idle slightly changes a bit, I dont have the thin tube so i cant spray it in a specific place. I tigtened the nuts that hold the carb down , that didnt help anything, I'm thinking vacuum leak? would that cause a whistling sound its pretty loud, Could i have a vacuum leak through the idle mixture screws? I dont know where else it could be coming from, the motor runs fine, carb is an edlebrock been on there for approx 5 years never a prob or rebuild. I dont know why changing the valve covers would cause this noise, maybe just a coincidence?