I second the accelerator pump as a possible issue. I cleaned my Rochester type B carburetor three times before I found the tiny port that the accelerator pump discharges into the carb throat was partially blocked. Assuming it’s a Rochester type “B” this may help.

Rochester Carburetor Information, Installation and Service Bulletins - Pre 1960

Thanks to Keith Hardy’s Old Online Chevy Manuals, for providing us this wealth of information.

Last edited by Phak1; 11/30/2019 2:41 AM.
Phil
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1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube
Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes
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