Originally Posted by Maskot
what is it used for?
LOOK...reread my post.
Originally Posted by Al.Fisherman
When the engine is COLD you may need some choke (restricting air flow through the carburetor), Rotate the lever counter clockwise (about 1/2 way to start), then when the engine is warmed up, rotate the lever fully clockwise (no choke).
A car/engines relies on the high-temperature of the engine to effectively burn fuel. When starting the engine from cold, the regular amount of fuel is not enough to deliver the required power.
The manual choke was a pull-out lever operated by the driver that opened decreased the carburetor's air-intake slightly, causing more fuel to be fed in and boosting power.
Leaving the choke closed for too long (once the engine had warmed up) resulted in an overly-rich mixture that made the engine stutter and stall. Opening the choke too soon would also stall the engine.
Modern cars use computers to work out exactly the right amount of fuel for each cylinder and injects that fuel automatically at precisely the right moment, making chokes thoroughly obsolete. The advancements came about (in Europe at least) because carburettor based engines could not meet emission targets.
Still of use to drivers of vintage cars. Also small carburated engines - snow blowers, snowmobiles, ATVs? motorcycles etc.