See Figure 1
All of the Mustang and Capri engines covered by this information utilize hydraulic valve lifters, except for the V6-170 cu in. engine. Valve systems equipped with hydraulic valve lifters operate with zero clearance in the valve train, thereby eliminating the need for adjustment. The V6-170 cu in. engine, however, is equipped with mechanical lifters that should be adjusted at the recommended intervals.
While all valve adjustments must be as accurate as possible, it is better to have the valve adjustment slightly loose than slightly tight, as burnt valves may result from overly tight adjustments.
- Remove the air cleaner assembly and disconnect the negative battery cable.
- Disconnect hoses leading to the Thermactor bypass valve.
- Unfasten the Thermactor bypass valve mounting bracket, then remove the bracket and valve assembly.
- Remove the two engine lifting eyes. Remove the alternator drive belt, loosen the alternator mounting bolts and pivot the alternator towards the fender.
- Remove the spark plug wires from the spark plugs and the rocker arm covers.
- When removing the rocker arm covers, first remove or reposition any wires and/or hoses which might block removal of the covers.
- Torque the rocker arm support bolts to 43-49 ft. lbs. (58-66 Nm).
- Reconnect the battery cable, place the transmission in Neutral (manual) or Park (automatic), and apply the parking brake.
- Place a finger on the adjusting screw of the intake valve rocker arm for cylinder No. 5. You will be able to detect the slightest motion of the rocker arm in this way. (Cylinder numbering is shown under Firing Order near the beginning of the section.) Valve arrangement, from front to rear, on the left bank is I-E-E-I-E-I; on the right it is I-E-I-E-E-I.
- Use a remote starter switch to turn the engine over until you can just feel the valve begin to open. Now the cam is in position to adjust the intake and exhaust valves on the No.1 cylinder.
- Adjust the No.1 intake valve so that a 0.016 in. (0.4064mm) feeler gauge has a slight drag, while a 0.017 in. (0.4318mm) feeler gauge is a tight fit. Turn the adjusting screw clockwise to decrease lash or counterclockwise to increase lash. There are no lockbolts to tighten as the adjusting screws are self-locking.
- Adjust the exhaust valve the same way so that a 0.018 in. (0.4572mm) feeler gauge has a slight drag, while a 0.019 in. (0.4826mm) gauge is a tight fit.
- The rest of the valves are adjusted in the same way, in their firing order (1-4-2-5-3-6), by first positioning the cam accordingly. For details, please refer to the chart.
- Remove all the old gasket material from the cylinder heads and rocker cover gasket surfaces, then disconnect the negative cable from the battery.
- Remove the spark plug wires and reinstall the rocker arm covers.
- Reinstall any hoses and wires which were removed previously.
- Reinstall the spark plug wires, the alternator drive belt, then the Thermactor air bypass valve and its mounting bracket.
- Reconnect the battery cable and reinstall the air cleaner assembly.
- Start the engine, then check for oil and/or vacuum leaks.