Honda K20 Valve Clearance Adjustment Diagram
Honda K20A2 and K20A3 cold valve-clearance chart with 1-3-4-2 adjustment order and separate exhaust specifications.
With the cylinder head below 38°C (100°F), the cited K20A2 and K20A3 use 0.21-0.25 mm (0.008-0.010 in) intake clearance. K20A2 exhaust is 0.25-0.29 mm (0.010-0.011 in); K20A3 exhaust is 0.28-0.32 mm (0.011-0.013 in). Set cylinder 1 at compression TDC, then rotate the crank 180 degrees for cylinders 3, 4 and 2 in firing order 1-3-4-2.
A valve-adjustment diagram is useful only after the valvetrain is identified. Engines grouped under the Honda K20A2 / K20A3 name can use hydraulic lifters, mechanical lash, pedestal rockers, screw adjusters or selective buckets. Those systems do not share one clearance or one adjustment technique.
K20 is a family name, not one valve-clearance specification. This page keeps the K20A2 and K20A3 exhaust branches separate because Acura's own service data does.
Use the interactive sequence as a position-and-recording aid. It does not replace the exact service manual, cam card or cylinder-head instructions. Record every starting measurement, keep reused parts in their original positions and turn the crankshaft by hand before starting the engine.
Interactive K20 valve-adjustment sequence
Branded downloads includedPNG and PDF exports carry the TorqueSheet logo, torquesheet.com, source-page URL, and republishing attribution request. The PDF source link is clickable.
Adjust No.1, rotate 180° to No.3, then 180° to No.4 and 180° to No.2.
Honda K20 Valve Clearance Adjustment Diagram
| APPLICATION / ITEM | SPECIFICATION | NOTES |
|---|---|---|
| Intake cold | 0.21-0.25 mm | K20A2 and K20A3 |
| K20A2 exhaust | 0.25-0.29 mm | Type-S branch |
| K20A3 exhaust | 0.28-0.32 mm | Base branch |
| Order | 1-3-4-2 | 180° crank between cylinders |
The two engines share the intake range but not the exhaust range. Confirm the engine code before choosing the gauge.
How to use this specification correctly
- 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.
- 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.
- 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.
- 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.
- 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.
- 06
Measure between rocker and cam at the specified location with both valves closed. Adjust for light drag using the gauge assigned to the confirmed engine code.
- 07
Hold the adjusting screw while tightening the locknut, then recheck. Rotate the crank 180 degrees in its normal direction before moving to the next cylinder in 1-3-4-2 order.
- 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.
- 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
K20 is a family name, not one valve-clearance specification. This page keeps the K20A2 and K20A3 exhaust branches separate because Acura's own service data does.
Confirm the UP marks and TDC alignment for the cylinder being adjusted. Do not rely only on crank rotation count if the timing system has been disturbed.
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
Measure between rocker and cam at the specified location with both valves closed. Adjust for light drag using the gauge assigned to the confirmed engine code.
Hold the adjusting screw while tightening the locknut, then recheck. Rotate the crank 180 degrees in its normal direction before moving to the next cylinder in 1-3-4-2 order.
Mistakes that damage valves or camshafts
- Using K20A2 exhaust clearance on K20A3
- Working on a warm head
- Moving 180 cam degrees instead of 180 crank degrees
- Confusing TDC overlap with compression TDC
- Skipping the final remeasurement
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
Honda / Acura Honda K20A2 / K20A3 specifications can change by model year, engine, platform, wheel, and installed component. Confirm the VIN or engine identity, part numbers, fastener condition, and the current manufacturer instructions before service.
Honda K20 Valve Clearance Adjustment Diagram FAQs
Are K20A2 and K20A3 valve clearances the same?+
Their cited intake range is the same, but exhaust differs: 0.25-0.29 mm for K20A2 and 0.28-0.32 mm for K20A3.
What is the K20 adjustment order?+
Use 1-3-4-2, rotating the crankshaft 180 degrees between cylinders.
Should valve clearance be checked hot or cold?+
Use the condition stated by the exact procedure. Temperature changes the dimensions of the head, valves and valvetrain, so a hot specification cannot silently be used cold.
Can a noisy valve be fixed by tightening it more?+
Not safely. Noise may come from low oil pressure, a collapsed hydraulic adjuster, worn cam, bent pushrod, damaged rocker, excessive clearance or an exhaust leak. Diagnose the cause first.
Why must the cam lobe be on its base circle?+
The base circle is the non-lifting portion of the cam. Measuring or setting preload while the lobe is opening a valve creates a false setting and can hold the valve off its seat.
Technical sources
TorqueSheet favors engine- and component-specific manufacturer instructions over unsourced universal values.
1Honda service informationOfficial Honda and Acura service publication lookup.↗