Idle Speed Control
After starting the car, engine speed must be sufficient to engage the clutch; approx 700rpm: "slip"; 1200rpm: total clutch.
The normal idle 550rpm is not enough to engage the clutch. This idle should be increased; the change of mode is made by the idle speed corrector connected to the front left brake.
The accelerated idle is regulated to 925rpm in order to have sufficient torque to hold the vehicle on an average slope.
On pressing the brake pedal, the fluid under pressure acts on a piston which controls the closing of a flap valve in the carburettor: the engine speed goes from 925rpm to 550rpm (Freeing the clutch and holding the vehicle).
By releasing the brakes, the piston opens the valve and the engine speed returns.
This corrector is also useful to avoid the disengagement speed being passed, when the accelerator pedal is released.