Edelbrock 1406 whistling

Being you have a 4150 carb base this is not what you need . If this plate you are showing is what your intake opening looks like this is your problem. Holley sells a plate for their strip dominater intake for use with a 4150 base carb this is the plate you will need and ues two gaskets one on each side. This plate you pictured will not work with your carb. Is this what your intake flange looks like can you get a pic of both base of carb and flange on intake. It would help.