Valve lash is the amount of clearance between the valve-train (rocker arm) and the tip of the valve. Lifters come in two types -- hydraulic and mechanical. Unless it is a competition-only racing engine, your 383 small block Chevy stroker engine most likely has a hydraulic lifter camshaft. Hydraulic lifter engines automatically adjust for clearance while mechanical lifters require a small, precise amount of lash. In either case, the sequence is the same but the actual valve lash/clearance has to be set with a different procedure.
Remove the coil wire or otherwise disable the ignition. Remove all wires, lines and accessories that are attached to the valve covers. Remove the valve covers and set aside. Locate the intake and exhaust rocker arms for the No. 1 cylinder. The No. 1 cylinder is on the left side of the front of the 383 Chevy engine.
Rotate the engine so the No. 1 exhaust valve begins to open (depressed down). The intake lifter is on the backside of the cam lobe (base circle) and the valve is fully closed: adjust the intake rocker arm nut so the adjacent pushrod can be just barely rotated with your index finger and thumb. This is "zero-lash," but a hydraulic lifter requires additional pre-load -- tighten the rocker nut one-half turn more. This valve is adjusted. Rotate the engine again in the same direction until the intake valve is almost fully closed.
Perform the same tightening procedure on the exhaust valve/rocker arm ("Exhaust Opening, Intake Closing"), and finish with the one-half extra turn of pre-load.
Continue in the same manner for the remaining cylinders using the "Exhaust Opening, Intake Closing" (EO-IC) sequence.
Reinstall the valve covers and any wires, lines or accessories that were previously removed. (If the old valve cover gaskets have been damaged when removing the valve covers, clean the surfaces and replace with new gaskets.)
Use the same sequence as for the hydraulic cam. Rotate the engine to the "EO" position so the No. 1 intake valve is on its base circle and fully closed.
Insert a feeler gauge between the valve tip and the rocker arm that is approximately .005 inches thicker than the recommended "hot lash" (to allow for parts expansion and clearance reductions when the engine is running).
Tighten the rocker nut so the feeler gauge blade can just barely slide in and out of the lash area. Tighten the rocker nut lock-screw.
Rotate to the "IC" valve position for that cylinder, and set the exhaust lash about .005 inches loose.
Repeat the process for all cylinders, and reinstall the valve covers and wiring.
