I have a 71 with a recently rebuilt 455 in it. Recently is has started making a weird noise out of the carb at heavy acceleration. My first thoughts say to replace the carb gasket which I plan on doing this weekend, but in case thats not it I wanted to see if anyone can identify this sound and what could be going on to cause it. I have pasted the link to the video but it sounds similar to the sound a a dirt bike makes when you rev it up. Check out the video.

 

Maybe I'm not hearing what you're hearing. Just sounds like the air rushing through the carb and into the engine. Since you are not in gear, there is no load on the engine. You can't duplicate the sound when it is driving because it won't react as quickly as when you blip the throttle in neutral.