How to Time a 94 4.3 L GM Engine

The 4.3-liter GM V6 that Mercruiser used in its inboard and inboard-outboard applications in 1994 had a quirk: you had to disconnect the throttle cable from the throttle arm before you adjusted the idle and time the engine before adjusting the idle once more -- with the cable still disconnected -- before reconnecting the cable and making sure the idle stop screw was set correctly.

Things You'll Need

  • Timing light
  • 12-volt battery
  • Shop tachometer
  • 8 AWG wire
  • Wire cutter
  • Wire stripper
  • Spray window cleaner
  • Chalk or white paint stick
  • Screwdriver
  • Torque driver
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Instructions

    • 1

      Connect a timing light to the No. 1 spark plug. Connect the timing light’s power supply leads to a 12-volt battery, if necessary.

    • 2

      Connect the gray wire from the ignition module to a shop tachometer.

    • 3

      Cut a piece of of 8 AWG gauge wire long enough to reach from the ignition module to a good engine ground, using a wire cutter. Strip 1/2 inch of insulation from the ends with a wire stripper.

    • 4

      Push one end of the jumper wire into the terminal for the purple and white engine wire at the ignition module. Ground the other end to a good engine ground to shift the ignition module into the base timing mode.

    • 5

      Clean the timing tab and the timing marks on the crankshaft torsional damper with a clean cloth and a spray window cleaner. Use chalk or a white paint stick to highlight the timing marks at 6 degrees BTDC to increase their visibility.

    • 6

      Start the engine and allow it to run at fast idle until it reaches its normal operating temperature. Allow the speed to drop until it reaches normal idle.

    • 7

      Snap the throttle cable barrel out of the bail on the throttle arm using a screwdriver. Turn the idle mixture screw to adjust the idle to 650 rpm on the shop tachometer.

    • 8

      Aim the timing light at the timing tab and turn the distributor with your hand until the timing is 6 degrees BTDC. Tighten the clamping screw to 18 foot pounds with a torque driver.

    • 9

      Adjust the carburetor idle rpm screw to 650 rpm, as indicated on the shop tach, if necessary. Recheck the ignition timing.

    • 10

      Stop the engine, remove the timing light and shop tach. Remove the jumper; if the jumper wire is left in place, the ignition module will remain in the base timing mode, preventing the timing advance features from functioning.

    • 11

      Reconnect the throttle cable. Push the remote throttle control backward and forward to ensure the throttle lever contacts the idle rpm adjustment screw every time you move the throttle to the "idle" position.

    • 12

      Turn the engine with the freshly adjusted timing off.