Carburetor Jet size

[turbohunter]

Really interesting stuff.
Am I understanding the relationship between thoat size and fuel use correctly?
In real world terms if you have a 390 that runs well on a certain cfm size (say 650) then you put a smaller size carb on the same motor (say 550) then you theoretically pull more fuel because of increased signal and get worse mileage?

[Heo]

See IT like this... The smaler
Carb needs smaler jets beacuse
The same amount of air moves
Faster and pull harder on the
Fuel

[JimNolan]

Confused me too, a 5% smaller airflow carb requires a 17% smaller fuel flow jet. Car seems to be running really good right now. If the plugs look too lean I'll increase the jet size.

[turbohunter]

Yup, get that Heo.
I should've added to my question that if you keep the same size jets in both carbs (the theoretical 650 vs 550 on the same motor) you'd actually use more fuel with the smaller carb because the increased signal would draw more?
So for the purposes of the thread you're rich.
Sometimes I need a hammer on the head

[My427stang]

Yup, get that Heo.
I should've added to my question that if you keep the same size jets in both carbs (the theoretical 650 vs 550 on the same motor) you'd actually use more fuel with the smaller carb because the increased signal would draw more?
So for the purposes of the thread you're rich.
Sometimes I need a hammer on the head

Yes, that is why as carbs get bigger, they get more jet, and/or the more efficient the booster, they get LESS jet.  It's all about what the booster is seeing (and the bleeds in the circuit too)