1950s car shaking

[Big Fins]

I always heard it was correct to oil the leather plunger too, but then thought that the gasoline would wash away the oil. Unless gasoline never touches the leather. IDK!

[dadscad]

By soaking the pump in either oil or gasoline helps to lubricat the pump bore in the carburetor so that the leather cup's sealing edge doesn't get damaged by friction rolling the edge up as it is pushed into the carburetor.

[Roger Zimmermann]

When replacing the pump, I'm using a small screwdriver placed under the leather to expand it. The first one I replaced did not expand and I had a hole during acceleration. The screwdriver trick solved the issue.