<VV> Jets for power

[Chuck Kubin]

---------Generally if you have to increase jet size it is because the carb is too 
large for the accompanying air flow. -------

Hey Warren,

Ya left me at the drugstore by the magazine rack on this one.  So the air flow determines the size of the carb? Can you elaborate?

Meanwhile, here's the simplified story on mixture. A 14-to-1 ratio of air to fuel is considered the "ideal" ratio to efficiently burn gasoline and release the maximum amount of energy. That means temperatures too hot for your engine.

At a higher ratio to power drops off (too lean). At a lower ratio the mixture burns cooler (rich).  A pilot can lean the mixture as he gains altitude and the air becomes less dense, but you don't have that option on you car, largely because you just ain't gonna gain that kind of altitude. 

The size of the carb is fixed, and as such, hopw much air will flow through it is fixed too ( A 390cfm carb flows 390 cubic inches of air per minute). You lock in the mixture when you install jets of a certain size. Simply put, bigger jets mix more fuel with the available air. Richer mixture. Smaller jets mix in less fuel. Leaner mixture.

Now, for all the fuel system engineers out there, I offer this simple explantion for something apparently not understood by some elements of the forum. You'll notice I haven't beaten the bejesus out of spark strength, spark or valve timing, distributor curves, cam lobe shapes, detonation or any of the things that will keep the thread going for the next six months.


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