After learning about this process, I decided to post this for others who may follow:
I asked how to adjust the valves on a 350 with hydraulic lifters. I got varied answers. I decided to ask a very well respected mechanic (works as a mechanic for the area concrete corporation company) for help. He came over the house and this is what he told me to do (which now makes perfect sense).
Theory of Operation
Engine valves allow passage of gases into and out of the cylinders. They are held in place be strong springs. They are opened in a timing sequence dictated by the camshaft. It takes two turns of the crankshaft to obtain one full revolution of the camshaft. If you look at the timing gears you will see the crankshaft gear has half the teeth of the camshaft gear. The camshaft lobes are designed such that they push the lifters upward at the appropriate time to open and shut the cylinder valves in the appropriate firing sequence. The energy of the lifter is transferred through the push rod that in turn pushes the rocker arm. As the lifter rises, it pushes the push rod up, one side of the rocker arm up, and the valve stem downwards (opening the valve). Adjustments are required in order to ensure the valves fully close and open. This is done using the rocker arm adjusting nut.
How to Adjust
Adjustments can be made in a two-step process. I would first warm the engine to ensure you obtain the working temperature thermal expansion of the metal parts in the engine. Place the engine at top dead center (TDC) such that the cylinder #1 (right front as you look toward the front of the truck) would be ready to fire. This is best accomplished using a socket wrench on the camshaft pulley center bolt. Since it requires two full turns of the camshaft, there is a possibility that at TDC, you can be 180 degrees out. The way I know I am on the right revolution is that I look at the #1 valves. If they are both closed at TDC, then it is on the correct revolution for TDC. Once the engine is turned to this position, you can adjust half the valves. When finished, you turn the camshaft one full revolution to finish the job.
Now that you are at TDC you can work on the following valves:
#1 Exhaust
#1 Intake
#3 Exhaust
#5 Intake
#7 Intake
#2 Intake
#4 Exhaust
#8 Exhaust
How to adjust the proper clearance
For each rocker arm for the above valves, do the following:
Mind you, this is all a ‘feel’ process. You feel with your fingers for the proper clearance (backlash). You adjust the rocker arm nut until you feel no up and down looseness between the push rod and the rocker arm.
Loosen the rocker arm nut until you feel the rocker arm jiggle. Place your fingers (it can be hot to the touch) around the push rod. Gently move it up and down. It should move a bit when you first start out. Slowly (trial and error method) tighten the rocker arm nut until you JUST feel no up and down play between the push rod and the rocker arm. This is zero backlash. Once at zero backlash, tighten the nut ½ turn. There! You set the first rocker arm. Finish the rest in the above sequence. Once finished the above valves, turn the camshaft one complete revolution) and adjust the following valves.
#3 Intake
#5 Exhaust
#7 Exhaust
#2 Exhaust
#4 Intake
#6 Exhaust
#6 Intake
#8 Intake
That should do it. After being told to do it this way by my mechanic friend, we fired up the engine without the valve covers on, and he placed his hand (palms down) gently over the rocker arms as the engine was running feeling for loose rocker arms. On my first try, he said I did great!
Anyway, for what it’s worth this was by valve adjustment job, and I feel confident it was done right. Hope this helps others new to the Chevy 350.
