VALVE LASH ADJUSTMENT
Solid-lifter valve lash. Cold vs hot specs. Rotation/position verification. The procedure most techs do wrong by skipping the position check.
Valve lash is the running clearance between the rocker and valve tip. Too tight: valves hang open, lose seal, burn. Too loose: valvetrain hammers itself, accelerates wear. Either error costs the customer engine life. Solid-lifter engines (some Toyota, Honda, motorcycles, performance applications) need periodic lash adjustment. Hydraulic-lifter engines self-adjust but the procedure for verifying still applies. Knowing how to check rotation position (so the cam lobe is on its base circle, not the lift) is the difference between a good adjustment and a guess.
During the heating cycle, valves and valvetrain components expand. The lash clearance allows for that expansion while still maintaining proper valve seal when closed. Specs are different cold vs hot because the components are different sizes at those temperatures. Always use the spec for the condition you're testing in.
You can ONLY adjust lash when the cam lobe is on its base circle (the round part, no lift). If you adjust while the cam is on the lift ramp, you're measuring against a position the valve doesn't see at rest, and the actual lash will be wrong. Position verification = rotate engine until you see the rocker NOT being pushed by the cam.
- Feeler gauge set — go-no-go style works well. Should slide between rocker tip and valve with light drag.
- Box-end wrench + screwdriver (or specialty adjuster tool depending on engine) — to hold the locknut while turning the adjuster screw.
- Crank socket + breaker bar — rotate engine by hand. Crank bolt is typical access; some engines have specialty crank turn tools.
- Service info with timing marks — locate TDC on each cylinder for valve adjustment position. Don't guess.
Competent tech: 30-60 minutes on a 4-cylinder solid-lifter engine. Where time goes — 10 min R&R valve cover, 15 min rotate through TDC of each cylinder, 5 min per valve adjustment × 8 valves, 5 min reassembly. V-engines or DOHC double the time.
INTERACTIVE — Adjust the Lash
CYLINDERS ADJUSTED: 0 / 4
4-cylinder engine, firing order 1-3-4-2. Rotate through TDC of each cylinder, adjust both valves, then move to the next. Tap a cylinder button to rotate to its TDC, then adjust both valves with the feeler gauge.
SELECT A CYLINDER
Pick a cylinder first to rotate to its TDC.
TYPICAL SOLID-LIFTER LASH SPECS · COLD vs HOT
| CONDITION | INTAKE | EXHAUST |
|---|---|---|
| Cold (room temp) | 0.006-0.008" | 0.008-0.010" |
| Hot (operating temp) | 0.008-0.010" | 0.010-0.012" |
Always check OEM spec for the specific engine. Exhaust valves expand more than intake (hotter), so exhaust lash is typically wider.
QUICK CHECK UNLOCKED ↓
QUICK CHECK
If the cam lobe is on the lift portion (not base circle), the valve is being pushed open and you're measuring the wrong gap. Always verify the cam is on base circle for the valve you're adjusting — typically each cylinder at TDC of its compression stroke.
Cold and hot specs are different — usually 0.002" apart. Apply the wrong spec and you've installed wrong-tension lash. Always check OEM service info for the spec that matches your engine's current temperature.
Tighten the locknut and the adjuster screw moves slightly. Always re-check the lash with the feeler gauge AFTER torquing the locknut. Most "wrong adjustment" comebacks are this exact step skipped.
Intake and exhaust have different lash specs — typically exhaust is 0.002" wider. Setting both to the same value tightens up exhaust and burns it over time. Always adjust per the spec for each valve type.
Valve Lash Adjustment
- Only adjust when cam lobe is on base circle — typically each cylinder at TDC of compression stroke.
- Use the spec for the temperature you're testing at: cold spec when cold, hot spec when hot.
- Exhaust valves expand more than intake; exhaust lash is typically wider (often 0.002" more).
- Feeler gauge should slide with light drag — not loose, not jammed.
- Re-check lash after tightening locknut. The screw can move.
- Tight lash burns valves. Loose lash hammers valvetrain. Both shorten engine life.
When a customer brings in a solid-lifter engine that's running rough or has a clatter, valve lash is the first place to look. Five-minute check tells you if it's adjustment, broken spring, or worn cam. Always do the lash before any major teardown call. Cheap fix on the front end saves the customer expense and saves your time on the back end.