How do you set carburetor jets?

Answer 1

Well, first of all, you don't "set" jets. Jets are removeable, and come in different sizes. They are used to set "off idle" mixtures, and adjust perfermance. Imagine a drinking glass. Picture the open end. A hole that size will flow X amount of gallons, in X amount of time. Right? Ok. Now if you were to jam a donut into the open end of the glass, thus reducing the diameter of the hole. Now, the hole will flow Y amount of gallons, in Y amount of time. The size of the hole controls volumetric flow. That is exactly what a jet does. When a motor is running at a given rpm, or climbing through the rpm range, say, under acceleration, the vaccuum a motor can pull, the jets are pretty much flow limiters. They are numbered by the size of the hole in them. I think the number is how many thousandths the hole is big, but, I am not totally sure about that. They are used in al carburaters that I know of. Reason being, a car that is tuned to run well at sea level, at altitude, wont. So, there needs to be an adjustment for this. It also makes carburaters more universal, to work on many different sized engines. Anyway, everyone is changed different. A holley, you pull off the float bowls, and they are in the jet block. Primary, front, secondary, back. On Carter, Edelbroc's, which really are a AFB design, just like the Carters. And, Quadrajets, GM's medium performance carb, all use the same system, which consisters of a jet, and a needle, that fits into the hole of the jet, and plugs it up to regulate the volume of flow. It probably is a more efficient way, than like with Holley, who just uses the jet. The Holley carb is geared more toward out, and out, performance, and is a little bit more ragged, and were used by all three of the big manufacturers, on their more performance orientated muscle cars. (however, I must say that most of them were not double pumpers, which, are much more ragged on the street) They all unscrew, and on the three AFB type carbs can be accessed from the outside of the carb, unlike the Holley. Jets usually do not need to be changedunless, you move to a new altitude, make perormance modifications to your motor, are transplanting the carb from another vehicle, or, maybe installing it for the first time. Even then, they are usually pretty accurrate. If you are having surge problems, or, say, are trying to get better gas millage, or, when idling in the garage, everyone is in tears within 2 minutes, I would not mess with it. It really doesn't make that much difference in a street vehicle, and, there are too many hazards, that, can, and will cause a level of chaos that will well exceede any expectations you may be envisioning.........chuck