Unsteday idle

Posted by happy On 2024/5/26 15:04:07

55 400 idle variations
With engine warm and the vacuum advance disconnected and the port plugged, idle is unsteady. A vacuum gage connected to the rear port of the carburetor reads max on the gauge. Visually comparing the distributor position to a 56 400 and firing order are the same. The 56 idle is smooth and vacuum is normal. I am at a loss as to what could be causing this unsteady idle, and high vacuum. Any suggestions as always would be deeply appreciated.
Happy