Hello Timmy.Welcome to JA.
The valves are absolutely out of adjustment.A simple compression test will verify this.Her are the instructions to adjust them correctly.Follow them to the "T".Old school mechanics have the 3 thread trick.That means that if you see 3 threads protruding past the rocker arm stud nut,then it's very close to where it oughta be.
The 3.4L and 5.7L engines use press fit studs.
Disconnect the negative battery cable.
Remove the rocker arm cover as outlined in this section
Remove the rocker arm nuts, balls and rocker arms. Place components in a rack so they can be reinstalled in the same location.
Fig. 2: After the valve cover is removed, unfasten the rocker arm retaining nut
Fig. 3: Remove the rocker arm and ball
Fig. 4: If necessary, remove the pushrods and place them in a labeled holder
Coat the bearings surfaces with a thin coating of Molykote or its equivalent.
Install the pushrods and make sure the rod is in the lifter seat.
Install the rocker arm, balls and nut. Tighten the nut until all lash is eliminated.
The engine must be on the No. 1 firing position before proceeding. This may be determined by placing your fingers on the No. 1 rocker arms as the mark crankshaft damper is rotated towards the "0" on the timing tab. If the arms did not move, it is in the No. 1 firing position. If they did move, turn the crankshaft one full revolution to reach the No. 1 position. Remember, the mark on the crankshaft balancer must be aligned with the "0" on the timing tab.
Adjust the valves as follows:
With the engine on the number 1 firing position, exhaust valves 1, 2 and 3 and intake valves 1, 5 and 6 may be adjusted. Back out the adjusting nut until lash is felt at the pushrod. Tighten the adjusting nut until all lash is removed, then tighten the nut an additional 11/2 turns to center the lifter plunger. Turn the engine one revolution until the "0" timing mark is once again aligned. Exhaust valves 4, 5 and 6 and intake valves 2, 3 and 4 may be adjusted.
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