Checking & Adjusting Valve Clearances
On the RSX, the cylinders go from passenger to driver side, numbers 1 – 4. Set the #1 piston (closest to passenger side) at top-dead-center (TDC).
Sub-Procedure: Rotating the Engine: (Steps 1 & 2)
- Jack only the passenger front side of the car so the front passenger wheel is off the ground.
- Put the car in a high gear (4th works) and rotate the wheel while looking at the cam gears. There will be considerable effort required to rotate the wheel. (You can reduce this effort by removing the spark plugs if you're so inclined.) On the cam gears, you'll notice there are several distinct marks. There is a punch mark (shown below in green) and a TDC mark (shown below in red) on both cam gears. There is an arrow pointing to the punch mark on the variable timing control (VTC) gear, which is the gear on the right in the below picture (can't see the punch mark in this picture). For piston #1 to be at TDC, the TDC marks on the cam gears must be aligned, as shown in the picture below in red.
Now you're ready to check the valve clearance for both the intake and exhaust valves. The intake valves will be closest to the intake manifold, the exhaust valves closest to the exhaust manifold. In the picture below, the green arrow indicates the valve adjusting screw, the red arrow indicates the locknut for the screw, and the blue indicates the position for the feeler gauge (between the valve stem and adjusting screw).
When the feeler gauge is inserted to check clearance, it should look like the picture below on the right.
For most people, simply checking to see if the valve is within spec is sufficient. Here at TOV, where maximum performance is desired, we want to adjust the valve to the minimum clearance so the intake and exhaust valves open as much as possible. The RSX-S's K20A2 valve specs are shown below. Please note the differences between intake and exhaust specs!
Intake: 0.21 - 0.25mm (0.008 – 0.010 in.)
Exhaust: 0.25 – 0.29mm (0.010 – 0.011 in.)
- Insert the appropriate thickness of feeler gauge between the valve stem and adjusting screw for cylinder #1. (I find it easier to remove the feelers from the holder if possible, as shown in the above picture.) For the intake valve to open as much as possible on the K20A2, you would use the 0.21mm feeler. If the valve is within spec, there should be a slight amount of drag/resistance.
How much resistance is correct? A good method to use is the "go/no go" method. If you're using the 0.21mm gauge to check the clearance, select the next largest gauge of 0.22mm. If the valve is at the spec of 0.21mm, you should NOT be able to insert the 0.22mm feeler. So, when you cannot insert the 0.22mm feeler and the 0.21mm feeler fits with resistance, that is correct. With practice, the correct amount of drag becomes simpler to detect.
- If the clearance is incorrect, you'll need to adjust. The locknuts are tightened to a low torque specification (14 ft./lbs. on K20A2), but will need to be broken lose. Loosen the locknut on the valve you need to adjust. It is best to leave the locknut slightly snug to allow for finer corrections to the adjustment screw.
- With the locknut snug, use a flathead screwdriver to increase or decrease the valve clearance based on your measurements. You will quickly realize that a small adjustment makes a big difference. It is here that the Honda valve adjustment tool (or similar) helps. See the picture below to see how the tool would work (my tool has a 10mm socket welded to a hollow tube). The tool allows the locknut to be held stationary when turning the adjusting screw, and the adjusting screw to be held stationary when turning the locknut.
- Make the locknut hand tight once the clearance is correct. Now, recheck the clearance.
- Once you've achieved the correct clearance, you'll need to use a torque wrench to torque the locknut to the correct spec (again, the K20A2 spec is 14 ft./lbs.). When the locknut is tightened, you'll have to recheck the clearance again. It will probably have changed slightly, which means you'll need to repeat the procedure again. This can become tedious until you've adjusted a few valves, since the clearance is going to change with even minor adjustments to the locknut. With some practice, you'll get a feel for what 14 ft./lbs. feels like and will only need to make sure you've got 14 ft./lbs. on the locknut versus actually moving it. Once you get this feeling down, you can use the Honda valve adjustment tool (or the like) to hold the adjusting screw while torqueing the locknut.
Be sure to check the clearance on each of the intake and exhaust valves. Remember, the clearance spec on the exhaust valves is different than the intake, so you'll need to select different feelers.
- Now, set the #3 piston at TDC by rotating the marks on the cam gears 90 degrees clockwise. The marks should look like those in the pictures below, with the punch mark shown in green, TDC mark shown in red, and arrow pointing to the punch mark on the VTC cam gear shown in blue. The left punch mark (green) and right punch mark (blue) should be inline with respect to each other and parallel to the ground.
- Check the valve clearance on the #3 cylinder's valves.
- Set the #4 piston at TDC by rotating the marks on the cam gears 90 degrees clockwise. The marks should look like those in the picture below, with the punch mark shown in green and arrow pointing to the punch mark on the VTC cam gear shown in blue. The left punch mark (green) and right punch mark (blue) should be perpendicular to the ground.
- For the last cylinder, set the #2 piston at TDC by rotating the marks on the cam gears 90 degrees clockwise. The marks should look like those in the picture below, with the TDC mark shown in red and arrow pointing to the punch mark on the VTC cam gear shown in blue. The left punch mark and right punch mark (blue) should be inline with respect to each other and parallel to the ground.
- Now you're done adjusting the valves. See if you need to replace the valve cover gasket, which would be indicated by any tears, cracks, or deformities in the existing gasket. If so, be sure to completely remove the existing gasket from the head and valve cover before installing the new one. The valve cover gasket should fit within the groove on the valve cover. If replacing the gasket, liquid gasket should be sparingly applied to points shown in the below picture (sorry, it is difficult to show them, but essentially, apply the liquid gasket to the 4 corners of where the valve cover will sit). Be sure to re-install the valve cover within 5 minutes of applying the liquid gasket.
- Place the valve cover back on the engine head. Install the black rubber washers if you removed them, making sure none are cracked or damaged (if so, replace them).
- Tighten the valve cover bolts in the correct sequence, indicated in the picture below. You should tighten them in several steps, incrementally tightening the nuts a little bit each time. The final torque spec is 7.2 ft./lbs.
- Install the valve cover breather hose and oil dipstick. Be sure to wipe the dipstick clean first.
- Install the coil packs by seating them over the spark plugs and connecting the wiring harness. Tighten the 10mm bolts for the coil packs to 8.7 ft./lbs.
- Install the ignition coil cover and its (4) 10mm bolts. Their torque spec is 8.7 ft./lbs.
- Install the 10mm bolts holding the cruise control cable and power steering pump bracket.
- Install the intake manifold cover and its (2) 10mm bolts. Done!
Copyright 2003, Temple of VTEC