/6 Idling Problems
I used to use piping hot beakers of carbon tet and methylene chloride
That's quite explanatory; both of those solvents are severely neurotoxic, and the effect is cumulative.
It always bears repeating: chemicals strong enough to clean a carburetor are by necessity extremely aggressive. They will dissolve the gluelike varnishes and gums and other kinds of gunk that you want gone, then they move right on to strip the anticorrosion coating off carburetor castings in a fairly big hurry (20 minutes to 2 hours or so, depending on strength/freshness and temperature of the cleaner).
It will also dissolve your hands, eyes, sinuses, etc. No matter how you are exposed to it -- by inhalation, by skin contact, etc. -- it will also work at dissolving your lungs, and it will dissolve the fatty matter that makes up your brain. Over time, this causes cognitive and behavioural problems similar to those seen in longtime body-and-paint men. At risk of sounding like I'm preaching, if you use this stuff, use it as intended (dipping, not splashing/pumping/spraying) and be about 3x as careful as you think you should be. I'm talking extremely good ventilation, completely shielded skin and eyes, etc. Methylene chloride by itself is grievously injurious to life. It is seriously toxic, causes cancer, and is readily absorbed through skin (liquid) and via mucus membranes and lungs (vapour). Add in the other strong chemicals found in these dip-type cleaners (MEK, toluene, acetone...) and you really do have a toxic waste dump in a 5-gallon can. These products, when used safely and carefully and disposed of properly (that can be a real trick!) can be useful for seriously filthy parts, but you have to handle them with
great respect and caution.
be very careful what solvents you choose as some will aggressively attack/destroy plastics
If there are any nonmetallic components left on the carburetor you're about to dip into carb cleaner, you're doing it wrong. And a further comment on the anticorrosion coatings mentioned above: carburetor castings stripped of their anticorrosion coatings are quite pretty when they come out of the dip, but once placed into service, they corrode
very rapidly. The potmetal (zinc die cast) of which most carb castings are made forms a dense, powdery corrosion that is all but impossible to remove successfully, and even if you could, the "eaten" metal no longer conforms to the precisely-machined and -drilled dimensions; passages are either clogged solid or grossly oversized, etc. This is one of the main causes of permanent death in the Holley 1920 carburetor -- irreversable buildup of crud and destruction of critical dimensions in the main metering block. It is also one of the reasons why "remanufactured" carburetors tend to be such junk; they are abusively "cleaned" with abrasive means (blasting -- it might not be sand, it might be soda or some other material, but it strips the coating nevertheless, and the coating is usually not reapplied).