How to Set the Timing on Chevrolet Carsby Contributing WriterUpdated June 12, 2017
Having your timing set to the proper specification will help to ensure the best performance and gas mileage from your Chevrolet car small-block. Having your timing "retarded" causes the spark plugs to fire later than they should, which will result in poor performance and gas mileage. Timing too far "advanced" causes the spark plugs to fire early, which can result in pinging under acceleration and can damage the Chevrolet car. No matter which small-block Chevrolet car you have, the timing procedure will be the same.
Under The Hood:
- How to Set the Timing on a Chevrolet Truck
- How to Set the Timing on a Chevy 350 Motor
- How to Set Up the Timing on a Chevy 400 Engine
- How to Set the Timing on a Chevy 454
Remove the number one spark plug wire and the spark plug from the cylinder head. Use the ratchet and a spark plug socket. You will be able to find the firing order on the top of the engine block. Most Chevrolet engine firing orders are "18436572."
Put the flat head screwdriver inside of the hole that the spark plug came from.
Place the socket and ratchet on the crankshaft pulley nut and start turning the crankshaft
Continue turning the crankshaft pulley until you feel the piston push the screwdriver up. When the piston reaches the top of the cylinder, the engine will be at top dead center. Put the spark plug back in and reattach the spark plug wire back to the spark plug.
Remove the distributor cap and make sure that the rotor inside of the distributor is pointing towards the number one spark plug. If so, then the engine is properly timed. If not, then the piston did not come all the way up or is too far down.
Crank the truck up and let the engine run until it is at the normal operating temperature.
Remove the vacuum hose that runs to the distributor. Shut the engine off.
Loosen the main distributor nut that holds the distributor into the block.
Hook one end of the timing light up to the number one plug wire and the other end to the battery.
Mark the crankshaft pulley directly across from the timing marks with a piece of white chalk. Start the engine again, holding onto the distributor so it doesn't move.
Point the timing light at the crankshaft pulley. The crankshaft pulley has timing marks behind the pulley to adjust the timing by. If the timing light does not land on the timing marks each time that the crankshaft pulley rotates, you will need to rotate the distributor until the marks match.
Rotate the distributor clockwise about 1/4 of a round and then check the timing marks again with the timing light. If the timing is accurately set, tighten the distributor nut back down and reconnect the vacuum hose. If the timing is still off, keep rotating the distributor clockwise until the timing light is timed with the timing marks on the crankshaft pulley.
Items you will need
Spark plug socket
Flat head screwdriver
Secure the car so that it cannot move while running. Engage the parking brake or place chock blocks in front of and behind a wheel to prevent the car from accidentally moving. Bring the car to operating temperature. With the car in park (or neutral), remove the air intake filter assembly. Disconnect any vacuum lines the assembly may be attached to and plug them if necessary. Disconnect the vacuum hose attached to the distributor vacuum advance and plug it. Turn the car off.
Attach the power leads of the timing light to the battery. The red lead is clamped to the positive terminal of the battery and the black clamp is attached to the negative terminal. The third cable of the timing light--the inductive pickup--is attached around the spark plug lead (wire) of the number-one cylinder (front, driver's side spark plug). Ensure the timing light cables are clear of any moving parts and restart the engine.
Aim the timing light at the marker (timing pointer) on the timing cover adjacent to the harmonic balancer, and activate the strobe (usually with a trigger). The harmonic balancer is a 6- to 8-inch diameter disk attached to the front end of the crankshaft. The flashing strobe of the light will illuminate the timing marks on the balancer to point to the initial advance the distributor is currently set at. If the indication is incorrect, loosen the distributor clamp bolt with the 9/16-inch open-end wrench or distributor wrench just enough so that the distributor can be turned without force. With one hand holding the light on the timing indicator and the other available to rotate the distributor, find the proper timing position of the distributor. Disconnect and set the timing light safely aside, and tighten the distributor hold-down bolt so that the distributor is secure. If the idle speed of the engine changed due to the timing adjustment, use the screwdriver to adjust the curb-idle adjustment screw so the proper idle is attained. Reattach any hoses to the air filter assembly and reinstall.
Items you will need
Inductive timing light
Distributor wrench or 9/16-inch open-end wrench
Park the vehicle on a level, paved surface and set the parking brake. Start the engine and allow it to reach normal operating temperature. When operating temperature is reached, turn off the engine.
Remove the rubber vacuum hose from the advance unit on the distributor. Insert the tip of a pencil into the end of the hose to plug it.
Look for the timing marker attached to the timing cover on the driver's side of the engine. It sits just above the harmonic balancer at the 1 o'clock position and is marked in a clockwise direction with numbers representing degrees before and after top-dead-center. Common marks are "Before 18-12-8-4-0-4-8 After." Spray the marker with parts cleaner and wipe it off with a shop rag to make the numbers easier to read. The common timing settings for the 400 small-block are 4 degrees before top-dead-center for automatic transmissions and 8 degrees top-dead-center for manual transmissions.
Find the timing mark on the harmonic balancer so you will know what to look for when you use the timing light. It's a notch in the surface of the balancer. If you don't see it, turn the bolt in the center of the crankshaft with a ratchet and socket in a clockwise direction.
With a wrench, loosen the distributor hold-down bolt just enough so that you can turn the distributor but it takes some effort.
Hook up the timing light. The large pickup lead with the plastic clip is attached to the number-one spark plug wire, which is the first wire on the driver's side of the engine. The red power lead is clicked to the positive battery terminal and the black one to the negative battery terminal.
Start the engine and shine the timing light down at the timing marker. You will see the notch in the balancer line up with a number on the marker. If necessary, turn the distributor to make the notch move to the appropriate number.
Turn off the engine, remove the timing light and reconnect the vacuum advance hose.
Items you will need
Install the remote starter switch so you can turn the engine over, by connecting one of the remote starter's leads to the positive terminal on the battery. Connect the remaining lead to the small S terminal on the starter relay. Momentarily press the remote starter button to "bump" the engine over and at the same time look at the harmonic balancer for the timing mark. The timing mark is a straight line across the balancer. Bump the engine over until the timing mark is at the 1 o'clock position as you are standing in front of the car looking at the engine. Use the white marker to highlight the timing mark line so it can be easily seen with the timing light.
Remove the number 1 spark plug using the spark plug socket. Place a finger across the spark plug hole and tap the remote starter button in short taps while you feel for the number 1 piston to come up on the compression stroke. This can be identified by high pressure air trying to escape past your finger. As soon as you feel it, stop bumping the engine.
Install a socket on the harmonic balancer bolt and rotate the engine slowly clockwise until the white line on the harmonic balancer moves to the 1 o'clock position. Look at the timing plate attached to the timing cover. Notice the top numbers are BTDC (before top dead center) followed, moving clockwise, by a V cut in the timing plate. This is top dead center. The next numbers in progression are ATDC (after top dead center) used for retarding the spark. Move the crankshaft with the socket until the white line is in the center of the V.
Install the spark plug in the number 1 cylinder and tighten with the spark plug socket. Remove the socket from the harmonic balancer and remove the remote starter switch. Remove the distributor cap using the Phillips screwdriver.
Install the distributor with the rotor tip pointing directly at the number 1 cylinder which would be the 5 o'clock position, if the distributor is not installed. If it will not drop all the way down with the rotor in this position, pull it back out and use the long common screwdriver to turn the oil pump driver rod a few degrees and try to install the distributor again. The rod can be seen in the hole for the distributor. Once the distributor is in, install the distributor hold-down clamp and loosely tighten the nut.
Place the distributor cap on the distributor but do not tighten it down. Lift it up slowly to see which terminal on the cap the rotor is pointing towards. This is the number 1 cylinder plug wire and the progression will rotate clockwise when installing the rest of the wires. The firing order for the 454 is 1-8-4-3-6-5-7-2. Remember all the odd number cylinders are on the driver's side and the even numbers are on the passenger's side.
Install the distributor cap and install the plug wires in this manner. Tighten the distributor cap with the Phillips screwdriver. Connect the electrical harness connector to the distributor. With the distributor rotor pointing directly at the number 1 spark plug terminal on the cap, rotate the distributor 6 degrees counterclockwise and tighten the hold-down clamp nut using a wrench.
Place a screw in the vacuum hose to the distributor to block the vacuum for the moment. Install the timing light by placing the red lead on the positive terminal on the battery and the black on the negative. Place the plug wire end with the clamp over the number 1 spark plug wire.
Start the engine and shine the light at the timing plate on the timing chain cover. Note where the timing mark is located on the plate. You want the white timing mark on 4 degrees BTDC. Loosen the hold-down clamp on the distributor and rotate the distributor in small amounts until the white timing mark is on the 4-degree BTDC mark. Tighten the hold-down clamp nut with a wrench, pull the screw out of the vacuum hose and plug the hose into the distributor.
Items you will need
Set of sockets
Spark plug socket
Set of wrenches
Remote starter switch
Long common screwdriver