Is there a diagram for the cylinder heads of a 1991 5.7 liter engine, especially the valve components? Thank you, Dan

G'Day mate
The motor you have is a 350 chevy
Pick any performance site in the USA and you will be swamped with any info you want.It is one of the best motors ever.It has unlimited options on whatever you want.
Type in a search 350 chev
Hope this helps

Hydraulic Lifters REMOVAL & INSTALLATION 4.8L Engines

1. Remove the rocker cover.
2. Remove the engine side cover.
3. Back off the rocker arm adjusting nuts and remove the pushrods. Keep them in order for installation.
4. Reaching through the side cover opening, lift out the hydraulic lifters. If your are going to re-use the lifters, remove them one at a time and mark each one for installation. They must be re-installed in the same locations. If a lifter is stuck, it can be removed with a grasping-type lifter tool, available form most auto parts stores.
   
5. Inspect each lifter thoroughly. If any of them shows any signs of wear, heat bluing or damage, replace the whole set. To install:
   
6. Install and coat each lifter with engine oil supplement.
7. Install the remaining components by reversing the removal procedure.
8. Once installation is complete, adjust the valves as described in the valve lash procedure. Fig. 1: Stuck lifters must be freed using a slide hammer type lifter removal tool
   

1. Remove the cylinder head cover.
2. Remove the intake manifold.
3. Back off the rocker arm adjusting nuts and remove the pushrods. Keep them in order for installation.
4. Remove the lifter retainer bolts, retainer and restrictor.
5. Remove the lifters. If your are going to re-use the lifters, remove them one at a time and mark each one for installation. They must be re-installed in the same locations. If a lifter is stuck, it can be removed with a grasping-type lifter tool, available from most auto parts stores.
6. Inspect each lifter thoroughly. If any of them shows any signs of wear, heat bluing or damage, replace the whole set.
7. Coat each lifter with engine oil supplement prior to installation. Tighten the retainer bolts to 12 ft. lbs. (16 Nm). Adjust the valves as described in the valve lash procedure.

1. Remove the cylinder head cover.
2. Remove the rocker arm shaft, rocker arms and pushrods. Keep all parts in order and properly identified for installation.
3. Remove the clamps and lifter guide plates.
4. Remove the lifters by reaching through the access holes in the cylinder head with a magnetic lifter tool. If you are going to re-use the lifters, remove them one at a time and mark each one for installation. They must be re-installed in the same locations. If a lifter is stuck, it can be removed with a grasping-type lifter tool, available form most auto parts stores. To install:
   
5. Inspect each lifter thoroughly. If any of them shows any signs of wear, heat bluing or damage, replace the whole set. NOTE: Some engines will have both standard and 0.010 in. (.0039mm) oversize lifters. The oversized lifters will have "10'' etched into the side. The block will be stamped "OS'' on the cast pad next to the lifter bore. and on the top rail of the crankcase above the lifter bore. WARNING
   New lifters must be primed before installation. Damage to the lifters and engine will result if new lifters are installed dry!
   
6. Prime new lifters by immersing them in clean kerosene, engine oil or diesel fuel and working the lifter plunger while the unit is submerged.
7. Prior to installation, coat the lifter roller with engine oil supplement. Re-used lifters must be installed in their original positions!
8. Install the lifters.
9. Install the guide plates and clamps. Tighten the clamp bolts to 18 ft. lbs. (26 Nm).
10. After all the clamps are installed, turn the crankshaft by hand, 2 full turns (720°) to ensure free movement of the lifters in the guide plates. If the crankshaft won't turn, one or more lifters may be jamming in the guide plates.
11. The remainder of assembly the reverse of disassembly.