Anyone help me on this one I have put carb kits in both my techmseth motors one on my old very old cub cadet tracktor and my old very old snowblower. They have the same carb put in the new needles and seats and cleaned everything very well.. if I don't shut the gas off at the tank after a few days seems like the carb leaks... any help there or just turn gas off.. thanks..

Sounds like the float may be sticking.
The fuel fills the float bowl and shuts off fuel, may be the seat?
I would shut the fuel off.

Left unfixed raw gas can start to fill the air space in your crank case and prevent the engine from turning over. Remove the bowl, turn the gas back on and actuate the float. Does or or does it not shut off the flow of fuel.