Maybe it's a mis stamped 53?

Had a similar issue with my 72 swinger's 225. turned out the reman carb had a jet 6 numbers bigger than stock. Bought the right jet and things were all good. Mine was supposed to be a #50 IIRC.


They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.