I have a vacuum gauge bouncing all over the place. The exhaust on the passenger side is about 100 degrees hotter than the driver side. front to back varies 10 to 20 degrees. It has a dual plane edle brock air gap manifold. I've checked for vacuum leaks, can't find any. It acks like it has one. My base timing is at 15 degrees, I have about 15 mechanical advance. I've tried advanceing the time timing as high as 30 degrees base timeing, and it doesn't help. I checked the carb over and over, I've adjusted the valves several times. Any ideas.

Did you try running a compression check to maybe narrow it down to one or more cylinders? With the vacuum gauge bouncing I would look at compression blowing back into the intake. Sounds like an intake valve is not sealing, being held open, lifters too tight, bad spot in the seat?

And/or possible broken valve spring.