Timing Marks on the 273 [66 Barracuda]

Demonracer said

Yes, unplug the vacuum line from the advance but be sure to plug the hose so you DO NOT have a vacuum leak.

Click to expand...

It shouldn't matter whether you plug the vacuum advance line or not. There should be no vacuum there at idle. If there is, you have a carb problem, or hoses connected incorrectly.