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Corvette Models Only (1970)

  1. With engine at normal operating temperature, choke valve open, air cleaner damper door fully open (if applicable) and air conditioner "OFF" (except 427"/390 HP & 400 HP), set parking brake firmly and adjust idle speed and mixture to attain idle speed as given in specifications.
  2. 427"/390 HP & 400 HP models with manual transmission and air conditioning require following adjustments; turn air conditioner "OFF" and disconnect idle-stop solenoid. Set mixture screws to obtain maximum idle RPM and adjust carburetor idle speed screw to achieve 550 RPM with transmission in Neutral. Adjust each mixture screw to give a 20 RPM drop, then back screws out (counterclockwise) 1/4 turn each. Turn "ON" air conditioner and reconnect idle-stop solenoid. Adjust solenoid to give 1000 RPM with transmission in Neutral.
  3. 427"/390 HP & 400 HP models with automatic transmission and air conditioning require following adjustments; turn air conditioning "ON", set mixture screws to obtain maximum idle RPM and adjust idle-speed solenoid to obtain 650 RPM with automatic transmission in "D" position. Adjust each mixture screw in (clockwise) to achieve a 20 RPM drop, then back each screw out (counterclockwise) 1/4 turn. Readjust idle-speed solenoid screw (if necessary) to give 650 RPM with transmission still in "D" position. Disconnect solenoid electrical connections, and set carburetor idle speed screw for 500 RPM, and connect solenoid.
  4. 427"/430 HP & 435 HP models, both automatic and manual transmission utilize following procedure; set mixture screws to obtain maximum idle RPM, and adjust carburetor idle speed screw (on manual transmission) or idle-speed solenoid screw (on automatic transmission) to 750 RPM for 430 HP automatic transmission and 1000 RPM for 430 HP manual transmission, or 750 RPM for 435 HP models with either transmission. Disconnect solenoid at electrical connection and set carburetor idle speed to 500 RPM, reconnect solenoid. Readjust, if necessary, carburetor idle speed screw on manual transmission models, or idle-speed solenoid screw on automatic transmission models to obtain specified RPM.
Corvette Idle Speed Specifications (1970)

Application Auto. Trans. Man. Trans.
350"/300 HP 600 700
350"/350 HP & 370 HP 750
427"/390 HP 600 800
427"/400 HP 600 750
427"/430 HP 750 1000
427"/435 HP 750 750
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