It sounds like you need a carb rebuild .Maybe a lean pop,you give it a little gas and flat spot and popping though the carb. does it run ok after the flat spot? Or does it pop all the way up on the reving of the engine?

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1936 1.5 wrecker,1937 gmc coe,1939 Chevrolet coe,1942 4x4 coe, 1942 coe,1946 dump,1947 2 ton dump,another 1947 2 ton dump,1950 coe,1967 c30,1937 cat 22,1936 Chevrolet 5 window foremans coupe, 1914 ford speedster.