Chevy 454 Timing Instructionsby Don Bowman
Ignition timing is used to ignite the fuel in an internal combustion engine at a particular time in an effort to burn as much of the fuel as possible in the power stroke. Complete combustion of the fuel would be ideal, however, given the inefficiency of the engine, this is very difficult. Timing is adjusted to maximize the fuel burn as much as possible. Fuel takes a certain amount of time to burn. As the engine rpm increases the time the fuel remains in the engine decreases exponentially, thus ignition timing is advanced to allow more time for combustion.
Mark the timing mark on the harmonic balancer with the white marker to make it more visible for the timing light. Look for the long straight line on the balancer and mark this. Look at the timing plate on the driver's side of the timing chain cover. Notice that it has a V cut in the center of the marker plate -- this is top dead center on the compression stroke. The numbers to the left of the V, looking at the engine from the front, are degrees of advance or how many degrees before top dead center. The numbers to the right of the V are degrees after top dead center. You always want to have the timing advanced or before top dead center.
Connect the timing light by connecting the black lead to the negative battery posts and red lead to the positive battery post. Lay the wires across the top of the radiator or intake manifold so they don't get caught in the fan. Connect the carbon connector probe to the number 1 cylinder spark plug wire by pressing on the connector handle and placing the jaws over the wire and allowing the jaws to close.
Disconnect the vacuum advance hose on the distributor and plug the hose with a screw. Start the engine. Shine the timing light at the harmonic balancer timing mark on the driver's side of the engine. Read the number on the timing plate adjacent to the timing mark on the balancer. The initial timing should be 4 degrees before top dead center (BTDC). If the mark is adjacent to a higher number BTDC, the distributor must be rotated clockwise to bring it down to 4 degrees. If the number is lower or after top dead center (ATDC), turn the distributor counterclockwise.
Turn the engine off. Loosen the distributor hold down clamp using a wrench. Start the engine and rotate the distributor as outlined previously. Walk around to the driver's side and check the timing to see if you moved the distributor enough to place the timing mark on the 4-degree mark BTDC. Keep adjusting the distributor until 4 degrees before top dead center (BTDC) is achieved.
Tighten the distributor hold down bolt using the distributor wrench. Pull the screw out of the vacuum advance hose and reconnect the hose to the distributor.
Items you will need
- Distributor wrench
- Inductive timing light
- White marker
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