Idle Speed & Mixture

NOTE: Before starling the engine, plug hose end for following systems: Starlet and Corolla HIC system. Tercel, Air Suction (AS) system for Federal model and HIC system, all models. Celica, Corona and Pickup, HAI system & MC system.

NOTE: Mixture adjustment is NOT a part of normal tune-up procedure and should not be performed unless carburetor is overhauled or vehicle fails emissions testing.

With air cleaner installed, run engine until it reaches normal operating temperature. Ensure that choke is fully open, all accessories are off and all vacuum lines connected. Check and adjust timing.
Place transmission in neutral and check that fuel level in carburetor sight glass is about mid-way. Remove idle mixture screw protective cover and idle limiter caps, if installed, and adjust idle speed to specifications.
Turn idle mixture adjusting screw to obtain maximum RPM. Now, turn idle speed screw until IDLE MIXTURE RPM is obtained. Repeat adjustments again, turning idle mixture screw to obtain maximum RPM, then idle speed screw to obtain idle mixture speed. Repeat until highest RPM is obtained before setting final idle mixture speed.

Once idle mixture speed is set after the highest possible RPM is obtained using the previous procedures, turn in idle mixture adjusting screw until normal IDLE SPEED RPM is obtained. Install replacement mixture screw cap and protective cover, if so equipped.

Fig 1: Carburetor Adjusting Screws (All Models)

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IDLE SPEED & MIXTURE

Application

Idle Mixture RPM

Idle Speed RPM

Celica & Corona

Man. Trans.

740

700

Auto. Trans.

790

750

Corolla

Man. Trans. ⁽¹⁾

820

650

Auto. Trans. ⁽¹⁾

880

750

Pickup

Man. Trans.

740

700

Auto. Trans.

790

750

Starlet

Federal

580

550

Calif.

730

700

Tercel

Man. Trans.

4-Spd.

600

550

5-Spd.

700

650

Auto. Trans.

850

800

⁽¹⁾	With power steering, set to 940/850 RPM.