Valve Clearance: Adjustments

Valve stem to valve rocker arm clearance should be within specifications with the hydraulic tappet completely collapsed. Repeated valve reconditioning operations (valve and/or valve seat refacing) will decrease the clearance to the point that if it is not compensated for, the hydraulic valve tappet will cease to function and the valve will be held open.

The use of positive stop rocker arm bolts eliminates the need to adjust the valve clearance. However, to obtain the specified valve clearance, it is important that all valve components be in a serviceable condition and installed and tightened properly.

If the clearance is less than specifications, install a 1.52 mm (0.060 inch) shorter push rod. If the clearance is greater than specifications, install a 1.52 mm (0.060 inch) longer push rod. The short or long push rod is available for service to provide a means of compensating for dimensional changes in the valve mechanism.

To determine whether a shorter or a longer push rod is necessary, make the following check.

1. Disconnect the brown lead (I terminal) and the red and blue leads (S terminal) at the starter relay. Install an auxiliary starter switch between the battery and S terminals of the starter relay. Crank the engine with the ignition switch in OFF position until the No. 1 piston is on TDC on the compression stroke.

Hydraulic Valve Tappets:

2. With the crankshaft in the positions designated in Steps 3, 4 and 5, position the tappet compressor using Tappet Bleed Down Wrench Tool T71P-6513-A or equivalent on the rocker arm. Slowly apply pressure to bleed down the tappet until the plunger is completely bottomed. Hold the tappet in this position and check the available clearance (0.098-0.198 allowable 0.123-0.173 desired) between the rocker arm and the valve stem tip with a feeler gauge.

Crankshaft Position:

3. With the No. 1 piston on TDC at the end of the compression stroke, POSITION 1, check the following valves:
- No. 1 Intake -- No. 1 Exhaust
- No. 4 Intake -- No. 3 Exhaust
- No. 8 Intake -- No. 7 Exhaust
4. Rotate the crankshaft to POSITION 2 and check the following valves.
- No. 3 Intake -- No. 2 Exhaust
- No. 7 Intake -- No. 6 Exhaust
5. Rotate the crankshaft to POSITION 3 and check the following valves.
- No. 2 Intake -- No. 4 Exhaust
- No. 5 Intake -- No. 5 Exhaust
- No. 6 Intake -- No. 8 Exhaust