The passages often clog right at the carb base gasket and can be drilled out. They are only about a half inch deep and then open into bigger passages below that rarely clog. You should be able to blow air in them and hear it at the tailpipe.
The bi-metal spring on the heat riser should lift the weight and close the passage when the engine is cold. It should lower the weight when the engine warms up.
Mac :{)
1962 K10 short step side, much modified for rally
1969 T50 fire truck, almost nos, needs a few things
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