The distributor installation?

The 1985 Buick Grand National with a turbocharged V6 engine is equipped with a computer-controlled ignition system that uses electronic components, including the distributor. Since there are no traditional plug wires to route, the process of installing the distributor correctly involves proper alignment of the ignition timing. Here's how you can align the distributor properly when dropping it in:

Crankshaft at Top Dead Center (TDC) for Cylinder 1:

Before dropping in the distributor, ensure that the engine is at top dead center (TDC) for cylinder 1 on the compression stroke.
You can do this by manually rotating the crankshaft using a socket and breaker bar on the crankshaft pulley bolt. Align the timing marks on the crankshaft pulley and timing cover according to your engine's specifications.
Distributor Rotor Alignment:

Inspect the distributor rotor. There should be a notch or mark on the distributor housing where the rotor sits.
Align this mark on the distributor housing with the mark on the distributor rotor.
Distributor Positioning:

Hold the distributor above the engine, ensuring that the rotor alignment mark matches the cylinder 1 spark plug terminal.
Slowly lower the distributor into the engine while simultaneously aligning the oil pump drive shaft with the distributor gear.
Seat the Distributor:

As you lower the distributor, the rotor should rotate slightly due to the gear engagement. Continue lowering until the distributor fully seats onto the engine block.
Ignition Timing Adjustment:

Once the distributor is seated, you may need to adjust the ignition timing using a timing light and the engine control module (ECM) connectors.
Follow the manufacturer's procedure for setting the base ignition timing, usually involving disconnecting certain connectors or jumping specific pins to put the ECM in diagnostic mode.

Please check the instructions in the images below.