At the phone company they took away our can of Berryman carb dip. The company doctor decided it was too toxic. He probably was not wrong, get it on you your hands and it won't come off for a week. It dyes your hands yellow, and they smell toxic for days. It dissolved latex gloves. Eventually all we had were cans of carb spray for rebuilds and that worked just fine. It was a fleet of 400 vehicles, all with carburetors so we rebuilt a lot of them, especially Holleys on the bigger trucks.
When it's done soaking in whatever you come up with, use a can of that spray carb cleaner with the straw. Jamb that straw against each passage and watch to see that it sprays out the other end of the passage. If it won't flow through the passage, blow compressed air through the passage using a blow gun with the low-pressure tip removed and replaced with a 3/16th brake line. That will usually unplug the passage. That was how I was taught to rebuild carbs by a Ford dealer mechanic that did all of the carbs at the dealer he was at in the 1960s and 1970s. Another tip he taught me was after the carb is rebuilt, blow with your mouth into the fuel inlet with the carb in the normal position, while still blowing flip the carb upside down and you should not be able to blow past the closed needle and seat. It's better to find out that that the needle and seat is not working properly before you install the carb. If all the passages are clean, minimum throttle shaft play, the float level is correct and the needle and seat is working properly your rebuilt carb should work well. Be gentle tightening those carb screws, you don't want to strip them out or distort the parts.
Prefill the carb bowl through the vent tube. Look to see that the accelerator pump squirts, and it should start up right away. Make your final idle air fuel adjustment using a little propane bottle slightly opened, it's called the "propane enrichment method". When you pass the propane over the carb if the idle goes up your too lean, if it goes down your too rich. if it stays the same, you're really close. Make sure both screws are adjusted the same and give the screws another 1/8 to 1/4 turn out so your slightly on the rich side. You need that to compensate for changes in barometric pressure and temperature... There is no better way to adjust the A/F mixture than using propane. As a licensed smog station that was the only way the State of CA allowed us to adjust carburetors. Except they wanted the final adjustment to be to the lean side. They wanted the rpm to go up 50 rpm when you gave it the propane. The 4-cylinder cars idled really rough adjusted that way with the AC on.
