Wiktionary
n. A type of valve having a small orifice and a needle-like plunger, allowing precise regulation of generally small flow rates.
Wikipedia
Usage examples of "needle valve".
You didn't say what you wanted it for, except that it was for a heavy duty gasolene engine, and you couldn't get the needle valve to work as you'd like.
He plunged home the knob that controlled the needle valve at the head of the cylinder and the small hissing ceased.
At the critical point, a needle valve gave way and the steam thrust madly out in a short but incredible blast.
No explosion followed, the needle valve controlling the powerful vapor perfectly.
He inspected the needle valve with much care, and had Foster on the front seat trying to start her afterwards.
Albright played with the needle valve until the engine ran smoothly.
As he began to twist open the cylinder's needle valve, Tom asked Bud to raise one of the robot's arms and tie the nozzle of the hose to it.
He stopped and tilted his head slightly, adjusting the needle valve on his indignation.