Re: 1953 Vicking 12D10V surging at high speed

[frankr]

As the float rises and drops in the carburetor, it operates a valve that controls the incoming fluid (also often called a needle & seat assy). You have a Tillotson carburetor and they made those seats in various diameters, all of which will physically fit. But the ones with a small diameter seat won’t allow the gas to flow into the carburetor as fast as it is consumed.