Whistle on acceleration

I am getting a loud whistle during any acceleration that is more than 'cruising'. It is almost always there, but once in a while is not. I can't get it to whistle when I open the hood and gun the engine, probably because it is not under a load. It is probably a vacuum leak, but could also be one of the smog valves that are installed in the vacuum system hoses. Has anyone else had this problem? It is a '79 400/4 speed.

what is yer intake duck work made of ?
when i made my cold air intake for my 95 it made a whistle on heavy acceleration almost sounded like a turbo.
but i would definatly look for vacume leaks thats probly not the problem though a vac leak would cause runnability problems like high idle and such

what is yer intake duck work made of ?
when i made my cold air intake for my 95 it made a whistle on heavy acceleration almost sounded like a turbo.
but i would definatly look for vacume leaks thats probly not the problem though a vac leak would cause runnability problems like high idle and such

It is the stock air inlet - The shaker (closed) and the cold air duct from the air cleaner to near the battery. I took the air cleaner off and checked the gasket on the carb - looks good. At the same time, I checked the vacuum hoses and could not find a problem. I plan on taking the shaker off, keeping the air cleaner base on to eliminate any chance of it being the cold air inlet stuff, and driving it to see if it still makes the noise. The worst thing it could be is a leaky intake manifold - but I just don't want to get into that right now.

Thanks for your response, and if you have any more ideas based on what I have just said, please let me know.

sounds good let us know if that fixes it