1998 Chevy Truck ADJUSTING VAULE LIFTERS

Your lifters are hydraulic roller lifters. There is no adjustment as it relates to measurments. The way you adjust these valves is as follows-- Bring no. 1 cylinder up to top dead center on the compession stroke--you can now adjust no. 2 and 5 and 7 intake valves and no. 3 and 4 and 8 exhaust valves. Loosen these rocker arms completely for about 5 minutes. This releases the hydraulic plunger inside of the lifter. Now tighten the rocker arm while spinning the push rod. When the push rod stops spinning stop. Now tighten the nut on the rocker arm 3/4 of a turn or 270 degrees. That's it! Now rotate the engine one complete turn ( 360 degrees) You can now adjust no. 3 and 4 and 6 and 8 intake valves and no. 2 and 5 and 6 and 7 exhaust valves.

BTW a noisy lifter on these motors should always be replaced.