If the engine has been rotated with the distributor removed, or if you are setting up a new or rebuilt Chevy small-block engine, use this basic three-step procedure to set the initial timing. This process involves syncing the crankshaft-rod-piston assembly contained in the engine block with the ignition timing system.
- Bring the internal engine components into position
This step is easier with two people. Remove the spark plug from the number one cylinder, and place your thumb over the hole. Have a friend rotate the crankshaft using a wrench or breaker bar placed on the harmonic damper bolt. When you start to feel the pressure of the compression on your thumb, the piston is close to its maximum stroke, top-dead-center. At the moment when the pressure subsides, stop rotating the engine because the number one piston is in position.
- Position the distributor's rotor
Use tape or white-out to mark the distributor cap's post for the number one cylinder on the base of the distributor and on the bottom of the distributor cap. Position the rotor at the mark, and insert the distributor into the engine block. Next, position and install the distributor cap, also based on the marks indicating the number one cylinder position. The engine is now at zero degrees but may not start.
- Start the engine
Reinstall the spark plug and wire and try starting the engine. Gradually, little by little, advance the timing by turning the distributor counter-clockwise until the engine starts. Now that the engine is running, install a timing light and perfect the timing by rotating the distributor. Be sure to tighten the distributor clamp.