Quadrajet making a whistling noise

[Reziel_1983]

Okay, so lemme explain what is happening.

I used to have an edelbrock 600 cfm carburetor on my 350. The 350 had headers, and edelbrock performer intake and a cam that was 3 steps above stock(I think).

We installed a bigger cam because my cam had a bad lobe and lifter so we just decided to upgrade to a bigger cam. With this new cam in and the edelbrock 600 cfm still on the engine we couldn't get the timing to be set. We could never get it to stop clattering, so we decided to try to put the old quadrajet back on. T

he timing on the engine is now set correctly but the carburetor is now making a whistling noise. We have had the quadrajet rebuilt before putting it back on. I'm a little new to engines and was wondering if anyone knows what might be wrong.

Thanks