Installing Distributor After Engine Has Been Rotated

Rotate crankshaft until No. 1 piston is at TDC on compression stroke. Ensure timing marks on crankshaft pulley and timing cover are aligned to TDC position.
Align distributor drive mark with housing mark, or turn distributor rotor to No. 1 spark plug terminal on cap and install distributor. Start engine and set timing to specification. See IGNITION TIMING in ADJUSTMENTS article in this section.

Fig 1: Exploded View Of Distributor

Courtesy of GENERAL MOTORS CORP.