quote:

ORIGINAL: bkmc24


so a question for you, ive been wondering this for a while, what happens when someone re-jets their carb? what is going on when that happens and whats the benefit of it. and another question, if i were to put a procharger on, would i have to do the fuel injection swap or will it fit on the carbed motor. i know a blower will fit on it but i dont want something that huge comming out of my hood lol.

quote:

ORIGINAL: Lee Willis
Jets looked kind of like a big allen head screw, they were usually brass, about 1/4 inch diamter, 3/8 long and have a tiny, very precisely diamtered hole in them, the were screwed/placed in the carb and it was through them (the precise hole) that the fuel is sucked out of the carburator bowl and down into the engine by the incoming air. If you have ever messed with nitrous kits, these are sort of similar to the jets you get with them. There was one for each barrel of the carb: 2 in a 2-barrel carb and 4 in a four barrel carb.

They came in all sizes of that tiny hole, say 68 thousandths, 72 thousands, 78 thousandths, etc., and you tuned the fuel/air ratio by changing jet size: a slightly larger hole gave more fuel. You would stick a fuel-air measuring sensor up the tail pipe and try various jets. There was a real airt to picking the right sizes for a modded engine and it was a critical tuning feature. When you added a new manifold or cam or increased compression ratio you have to re-jet the carb.

Most "modern" (new) carbs come with jets for a particular engine you buy them for. If you go modding the engine you may have to change the jets, otherwise it can run too rich or too lean