A surging condition at part throttle, or constant speed can be caused by several things.

• Look for vacuum leaks – Carburetor mount, vacuum lines, intake manifold.
• Be sure the mounting gasket is not leaving any openings.
• If by chance you are not using an air cleaner, then plug the air cleaner stud hole in the base of the Thermoquad.
• If large vacuum take-off in base of Thermoquad is not used, then plug with pipe plug in box.
• If vacuum tube for spark advance is not used it should be plugged.
• If no air leaks then the primary side of the carburetor is probably too lean.
• If wide open acceleration is good then change to a metering rod with a richer part throttle stip.