Definition
A carburetor mounted below the engine in which the induction air enters at the bottom and flows upward through the carburetor and into the engine's intake manifold. The fuel is metered into this rising airstream, mixed with it, and carried up into the cylinders.
Plain English
A carburetor positioned beneath the engine where the air going into the engine travels upward through it. Air comes in from below, picks up fuel along the way, and continues upward into the engine.
Context Anchor
Seen in aircraft engine maintenance, induction system descriptions, and carburetor installation diagrams.
Derivation
Updraft' simply means an upward current of air. The name describes the direction the air moves as it passes through the carburetor — upward, rather than downward (downdraft) or sideways.
Why Pilots Care
The mounting position affects how fuel behaves if the engine floods or leaks. In an updraft carburetor, excess fuel tends to drain back down and out rather than pooling in the intake manifold, which changes how starting and flooding issues are handled.
Intuition Check
Do not read 'updraft' here as a weather updraft under a cloud. In an updraft carburetor, it simply means the air flows upward through the carburetor.
Example Sentence 1
The older radial engine used an updraft carburetor mounted beneath the accessory case, so the induction air flowed upward into the cylinders.
Example Sentence 2
An updraft carburetor sits below the intake manifold so the mixture rises into the cylinders.