The best way to check float level is remove the carb top, turn it upside down. The top of the float should be just above the flange on the top, turn it over and it should drop about 3/8" to 1/2". Check the float while inverted blow in the gas supply inlet, should not pass air, lift the float and it will pass air. May sound "shade tree" but it works. I have 2 Rochester B carbs on my 248 GMC and they work fine, no leaks at all and it runs good.
