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To install the distributor with the engine disturbed:
Turn the engine to bring the No. 1 piston to the top of its compression stroke. This may be determined by inserting a rag into the No. 1 spark plug hole and slowly turning the engine over. When the timing mark on the crankshaft pulley aligns with the 0 on the timing scale and the rag is blown out by compression, the No. 1 piston is at top dead center (TDC).
On Mark IV (big block) V8 engines there is a punch mark on the distributor drive gear which indicates the rotor position. Thus, the distributor may be installed with the cap in place. Align the punch mark 2 degrees clockwise from the No. 1 cap terminal, then rotate the distributor body 1/8 turn counterclockwise and push the distributor down into the block.
Install the distributor to the engine block so that the vacuum advance unit points in the correct direction.
Turn the rotor so that it will point to the No. 1 terminal in the cap.
Install the distributor into the engine block. It may be necessary to turn the rotor a little in either direction in order to engage the gears.
Connect the negative battery cable, then tap the starter a few times to ensure that the oil pump shaft is mated to the distributor shaft.
Bring the engine to No. 1 TDC again and check to see that the rotor is indeed pointing toward the No. 1 terminal of the cap.
After correct positioning is assured, turn the distributor housing so that the points are just opening. Tighten the retaining clamp.
Install the cap and primary wire. Check the ignition timing. Install the vacuum hose.
Fig. 1: Scribe matchmarks for the distributor housing and rotor alignment
Fig. 2: Lift upward until the shaft clears the bore in the intake manifold, then tilt and remove the distributor
HEI Distributor, 1975 and later