Nissan SR20DET Valve Clearance and Lash-Adjuster Diagram

How to use this specification correctly

1. 01

   Confirm the engine code, model year, cylinder-head casting and whether the valvetrain is original. Obtain the exact vehicle service procedure or the cam, lifter and rocker instructions for modified hardware.

2. 02

   Let the engine reach the specified hot or cold condition. Disconnect the battery when removing powered components, protect open oil drains and label coils, hoses, brackets and cover fasteners.

3. 03

   Remove the cover without dropping debris into the head. Inspect oil supply, springs, retainers, rocker tips, cam lobes and pushrods before changing an adjuster; mechanical damage cannot be repaired by hiding it with a tighter setting.

4. 04

   Rotate the crankshaft only in its normal direction with the specified socket. Put the valve being measured on the cam lobe's base circle or place the named cylinder at compression TDC according to the selected source.

5. 05

   Measure with clean gauges held square to the specified contact surfaces. A gauge should have an even light drag; forcing it through or measuring at an angle gives a false result.

6. 06

   For stock hardware, inspect oil supply, lash-adjuster contact/sliding surfaces and adjuster movement using the factory procedure. Keep every rocker, shim and guide identified by original position.

7. 07

   For a solid-pivot conversion, measure and select shims only by the conversion and camshaft instructions; record both legs of every rocker and recheck after assembly.

8. 08

   Rotate the crankshaft through two complete revolutions by hand. Recheck timing marks, all adjusted positions and free movement before reinstalling covers with serviceable seals.

9. 09

   After startup, confirm oil pressure and listen for abnormal ticking. A persistent noise, misfire or low compression requires diagnosis of oiling, cam wear, lifter condition, valve seating and geometry rather than another blind adjustment.

Application and valvetrain boundaries

Nissan's SR20 service material identifies hydraulic lash adjusters. Their job is to remove operating clearance with engine-oil pressure, so a generic cold lash chart is the wrong service model.

SR20 rocker shims and guides are not permission to set conventional lash. Keep them paired and oriented. Tomei's solid-pivot instructions explicitly create a different system that requires calculated cam clearance.

How to use the interactive diagram

Select each point in order and mark that position on a worksheet only after the cam is on its base circle. The point labels describe the documented workflow; they are not a universal permission to tighten every rocker at once.

When a procedure uses two crank positions, finish the listed valves at the first position, rotate exactly as directed and complete the remaining group. When it follows firing order, move one cylinder at a time and verify compression TDC.

Measurement and adjustment notes

For stock hardware, inspect oil supply, lash-adjuster contact/sliding surfaces and adjuster movement using the factory procedure. Keep every rocker, shim and guide identified by original position.

For a solid-pivot conversion, measure and select shims only by the conversion and camshaft instructions; record both legs of every rocker and recheck after assembly.

Mistakes that damage valves or camshafts

• Publishing a universal SR20DET feeler-gauge clearance
• Bleeding or compressing an HLA with dirty solvent
• Mixing rocker shims between valves
• Treating a solid-pivot cam card as a stock HLA specification
• Ignoring low oil pressure or aerated oil

Before the covers go back on

• Every measurement recorded by cylinder and intake/exhaust position
• Locknuts or pedestal bolts tightened with the specified tool and torque
• Pushrods seated in lifter cups and rocker seats
• Oil passages, seals and cover rails clean
• Crankshaft turned by hand with no binding
• Engine-specific firing order and timing marks rechecked