Chevy 350 possible edelbrock carb. problem. Need help
When you took it to your mechanic you said he determined TDC and remarked the balancer. Did you ask him why the original mark on the balancer was off? Did you ask him why he unpluged the vacuum advance? You definitely need to know if there is a problem with the vacuum advance. The vacuum can on the distributor could be shot, something could be broken on the plate inside the distributor not letting the advance work. When you cleaned the carburetor did you soak it or just use carb spray? Here is a Wiki article on HEI distributors to read. Read the section on the Idle transfer slot thru the example of a typical performance ignition advance curve. This is a lot of information to help you understand what is happening. Even if you don't do the work on it you will know what needs to be done.