Flat spot in carburetor

[michael a]

Marvel Schreiber carb purchased as new rebuild off Ebay. Car starts and runs fine on the flat but if you get into it or pull a hill it has no power you have to go to almost idle to get it to hit on four and if you ease into it gradually it picks up speed and runs well until you get to a hill then as you give it fuel it just bugs down. Kind of acts like water in the fuel any thoughts?

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