Attention: The first cylinder is located closest to the radiator. The following procedure assumes that the distributor (if available) installed in the appropriate position. If you are trying to find TDC in order to orient the distributor correctly, the piston position must be determined by compression in the first cylinder and then matching the ignition timing marks or installing a special tool on the flywheel.
Top dead center (TDC) is the highest point of the piston stroke in the cylinder. Each piston reaches TDC on the compression stroke and on the exhaust stroke.
Setting the piston to TDC is an essential part of many procedures, such as removing the chain and distributor.
Before starting this procedure, make sure the shift lever is in neutral, apply the handbrake, or block the rear wheels. Disable the ignition system by disconnecting the ignition coil wire from the center terminal of the distributor cap and grounding it to the engine block with a jumper wire. Remove the spark plugs.
To set either piston to TDC, turn the crankshaft using one of the methods below. When viewed from the front of the engine, the crankshaft rotates clockwise.
Have an assistant turn the ignition key to the start position for a short time and give him a signal when the crankshaft approaches the desired position. Then install the key and correct the position of the crankshaft.
Method 1
Turning is carried out using a ring wrench mounted on the bolt of the front end of the crankshaft.
Method 2
The crankshaft is rotated using a spanner wrench mounted on the central nut of the generator pulley (through V-belt transmission). Locate the spark plug wire terminal on cylinder 1 on the distributor cap. If the terminal is not marked, trace the wire from the spark plug to the distributor cap (the first cylinder is located closest to the radiator).
Mark the terminal with felt-tip pen or chalk on the distributor body or actuator cover.
Remove the distributor cap.
Turn the crankshaft so that the alignment marks are aligned (located at the front of the engine).
Some engines do not have these alignment marks, instead there is a alignment hole or mark in the flywheel that must align with the hole or pointer in the rear flange of the cylinder block. On this engine, rotate the crankshaft so that the distributor slider approaches the spark plug terminal of the first cylinder, then rotate the crankshaft a little more so that the mounting holes or marks are aligned and a suitable drill can be inserted into them (if possible).
Flywheel timing options (1) and rear flange (2) cylinder block
Option 1 (early car models)
Option 2 (later model cars)
Distributor slider (if there) should now point exactly to the mark you made on the distributor body or actuator cover.
If the slider is 180°from the mark, the piston of the first cylinder is at TDC on the exhaust stroke.
To move the piston to TDC on the compression stroke, rotate the crankshaft one full revolution (360°) clockwise. The slider should now point to the mark on the distributor or drive cover, and the ignition timing alignment marks should be aligned.
Attention: With the cylinder head cover removed, both rocker arms of the valves of the first cylinder must be free and have a noticeable gap.
Caution: When the slider points to the correct terminal and the timing marks fail to align, the drive chain may have slipped off the sprocket teeth or was not initially installed correctly.
Once the piston of the first cylinder is set to TDC on the compression stroke, the TDC for any of the remaining pistons can be found by simply turning the crankshaft and following the firing order of the cylinders. Mark the wire terminal locations of the remaining spark plugs using the same method. When the distributor slider points to one of these marks, the piston of the corresponding cylinder is at TDC on the compression stroke.