On my trip home cross town my 216 started hesitating horribly on the bottom end but would clean up with a good amount of throttle. I checked and found the vacuum advance not moving at all. I used a vacuum pump...nothing moved, moved the manifold hose to the advance unit and ...more nothing.
So new advance unit has been ordered.

The engine would (until this happened) start on the first try with one pump of the accelerator and just a bit of choke. Now I am having to pull the choke almost all the way out and work the throttle a bit. I did have 2 backfires through the carburetor while trouble shooting this issue. Does vacuum advance have any effect on start up? Or is there more likely another issue at play possibly caused by the backfires?
I have the vacuum line at the carburetor disconnected and the port is plugged.

Jackie