This week’s blog is going to be another addition to our valve adjustment series. Eventually, we will have gone through each Honda engine series and shown you how to do a valve adjustment on it. This week’s focus is on K20 engines! In this post, I will be performing two valve adjustments at once. If you’ve been keeping up with the blog, you will have seen the articles on my brother’s EG with the K20 engine, and I figure since his car is nearing completion (again), I want to make sure his car is all within specs before I send it back out to him. If you want to read any of the articles about the journey of his car, you can click on the links below.
As for doing one on my car… I’m pretty hard on it, so I try to keep it in tip-top shape. This means I’m doing maintenance at intervals of every few months rather than every few years. It’s actually a lot of fun for me to pull off the valve cover and do a valve adjustment, and I’ll pretty much use any excuse to be in the garage working on a car. I figured it would be cool to do a write-up on both the cars at the same time and sort of break up the monotony of just showing pictures of one car.
So, real quick, let me give all you new readers a backstory about our K20s. We purchased them together at the same time from HMO (Honda Motors Online) about 4 years ago. Both of our swaps are JDM DC5 K20A swaps, with only bolt-ons. As you can see from the valve train picture below, they are incredibly clean, and that is why I only recommend people get their swaps from HMO. Eric’s car alone has been across the United States a total of 4 times, and mine has seen countless hard miles on the track. Essentially, these motors are just stock DC5 swaps with a tune, thus maintaining that OEM reliability. With regular maintenance, it’s easy to keep them long-lasting for many years to come, which brings us to the valve adjustment HOW TO.
Starting off, let’s clear a few things up. Unlike the B series, there are a few different styles of K series. So, if you have something other than a K20a, K20z3, or K20z1, things might be a little different. BUT… The motions are pretty much the same; you would just need to look up specs based on your motor. You will also notice that mine is not in a Civic Si, or RSX Type S. If you are doing a valve adjustment on any of those, there will be more things to take off, i.e., the plastic intake manifold cover, vacuum lines from intake to valve cover, and possibly others. You should be able to figure out how to remove those without me showing you.
Here are the tools I used, but again you might need some others depending on what you have to take off. All the valve cover bolts, coil pack, and ground bolts/nuts are 10mm. You’ll also need a 19mm for the crank pulley bolt (this will be used to turn the engine manually). A spark plug socket, long extension, ratchet, jam nut valve adjustment tool, feeler gauges, magnet, breaker bar, a rag, and some Hondabond.
The most important tool you need that will allow this to go easily is the Jam nut valve adjustment tool. Some people claim that you can use a 10mm closed-end wrench and a flathead screwdriver (which is essentially what the jam nut tool is), and I’m sure you could do it this way, but it keeps the frustration low throughout the whole job if you just use the correct jam nut valve adjustment tool. Having angled feeler gauges makes life a lot easier too.
I also have a few other tools in the picture that I used because I had to snip some zip ties and need to take my strut bar off too.
Step 1:
You are going to break the front right wheel loose. Jack the front of the car up and rest it on jack stands. Remove the wheel; this is going to give you access to the 19mm crankshaft pulley bolt. (If you don’t want to jack the car up, you could also turn the wheels to full lock to the right, and you could sneak a ratchet in that way. But in keeping with our “low frustration” motto, just remove the wheel, and it will be so much nicer.)
Once you remove the wheel, you will gain easy access to the crank pulley bolt, which is 19mm. To make life a little easier, I pair a 19mm socket with a 3/4 ratchet just to make turning it a little easier.
I will leave the ratchet on there throughout the whole process of the valve adjustment because you will need to turn the engine manually with it to TDC (top dead center) for each cylinder. JUST DON’T FORGET TO REMOVE IT BEFORE YOU START THE CAR!!!!!!!!!!!!!! SERIOUSLY!!
Step 2:
Removing the valve cover. Like I said earlier, your car might have some other plastic pieces on it that mine doesn’t, but I’m not going to show you how to remove those. They should all just come off with a 10 mm socket. As you notice, I don’t even have a spark plug wire cover, so I’m just going to jump right into removing the 10 mm nuts holding the valve cover on. There are 6 total that you need to remove.
Then remove the two 10mm bolts holding the coil pack harness (yours might not be bolts, they may be 10mm nuts on studs)
Now remove the 10mm bolts hold each coil pack to the valve cover.
Remove the 10mm ground wire bolt.
Now one at a time you can lift the coil packs out enough to un-clip the plug. be careful not to pull too hard on the coil pack harness.
Next, you will carefully move the coil pack harness back toward the firewall. Your valve cover should look like mine now. I forgot to mention that you also need to remove the dipstick. Notice that I have removed all bolts, yet I have left the grommet washers on still. Next, I will show you how to remove them without losing them, or having them fly everywhere. (Yes, that’s a chip in my real Spoon valve cover.)
Now I’ll show you how to take off those washers without losing them. Take the magnet that I told you to have handy and remove each washer with it one by one. You can leave the rubber grommet on; they should stay in the valve cover as you remove it. Just be careful and pay attention when removing the valve cover so you don’t lose any of them. If your valve cover grommets and washers are old, this would be a great time to replace them. I will be reusing mine since they are fairly new.
I removed the spark plugs for two reasons. One, I get to inspect them and see how the engine is running, and two, removing them will help rotate the engine around using that ratchet on the crank pulley much easier. This is because compression won’t build in the cylinders since the spark plugs are gone. Again, technically, you don’t need to remove them, but let’s not get frustrated. It’s also easier to get the marks on the timing gears to line up because the compression when the engine reaches TDC won’t push the piston back down slightly. (take all 4 out plugs out)
Now, you are going to remove the valve cover. It will be on there pretty good, especially if your valve cover hasn’t been off your engine for 100,000 miles. DO NOT take anything metal and try to pry between the valve cover and the head, as you can easily scar the head where the valve cover gasket seals, and this might cause there to always be a leak. I take my hands and place them like this.
I shift the valve cover back and forth to break the seal. You could also use a plastic scraper or interior panel remover to pry lightly between the head and the valve cover. Shifting the valve cover forward and backward will also cause the grommets to move up the studs, allowing the valve cover to shift back and forth more. You’ll know when it’s loose enough to remove. I tried to illustrate below how the valve cover is slightly shifting front to back (that’s why it’s a little out of focus).
The valve cover should now just lift off. I don’t recommend replacing the spark plug hole gaskets because they are a pain in the ass to hammer in, and I usually end up destroying them. You shouldn’t need to replace them anyway unless oil is pooling in your spark plug tube.
Step 3:
A valve adjustment should be done when the engine is COOL, below 100 degrees F. Realistically, you should do it in the morning before you even start your car. As we all should know, heat causes metal to expand, thus throwing off your measurements in the valve lash setting. Plus, if you let the engine sit all night, most of the oil will drain out of the head so when you remove the valve cover it won’t leak out as much. (no matter what, some is going to leak though)
The K series engine (like most all Honda engines) has a firing order of 1, 3, 4, 2. Cylinder #1 is the one closest to the timing chain/gears, and cylinder #4 is closest to the transmission. There are four valves per cylinder (two exhaust and two intake) and there are four cylinders so that gives us a total of 16 valves. To do a valve adjustment you must TDC (top dead center) for each cylinder and only one cylinder can be TDC at a time. I’m going to show you how to ensure you are correctly setting each cylinder to top dead center. There are marks on the timing gears, and the lobes on the cam will point in a certain direction. (Sticking something in the spark plug hole and watching it rise as you turn the crankshaft bolt will tell you when the piston is all the way up, but that’s not necessarily TDC. It might not be on the compression stroke. Therefore, please don’t use this method; you might incorrectly adjust your valves that way.)
Below is cylinder #1 at TDC
The arrow is pointed up, and there are lines on each timing gear, and they will be pointing towards each other.
Then the cam lobes will point inwards towards the spark plug tube, with the exhaust side pointing towards the theoretical 2 o’clock and the intake side pointing to the theoretical 10 o’clock. Use the VTEC lobe for guidance, as it is the easiest to see (largest middle lobe).
Now we are moving to cylinder #3 (remember the firing order 1, 3, 4, 2). Take your ratchet on the crank pulley and rotate it clockwise until the arrows on the cam gear move 90 degrees and look like this.
also note the lines on the cam gears, the one you can see (intake cam gear) line is pointing upwards, and the exhaust side (which you can’t see due to the shock tower being in the way) will be the exact opposite, pointing downwards. Remember, this is TDC for Cylinder #3.
Again, take note of the VTEC cam lobe and how they point inwards towards the spark plug tube: theoretical 2 o’clock for the exhaust cam, and theoretical 10 o’clock for the intake cam.
Now let’s move to TDC on cylinder #4 (remember the firing order 1, 3, 4, 2), and cylinder #4 is the one closest to the transmission. Take your ratchet on the crank pulley and rotate clockwise until the arrows have moved another 90 degrees pointing downward.
Take note of the lines on the cam gear and how the one on the intake cam points forwards towards the radiator, and the exhaust one (which again can’t be seen because of the shock tower) points the opposite way backwards towards the firewall.
And the cam lobes for cylinder #4 will be pointing in the same direction as the previous cylinders, inwards towards the spark plug tube—theoretical 2 o’clock for the exhaust side and theoretical 10 o’clock for the intake side.
The markings for the fourth and final cylinder, cylinder number #2, look like this. Remember to take your ratchet on the crankshaft bolt and rotate it again in a clockwise motion until the arrow has moved another 90 degrees, like this.
Now you can see the line on the exhaust cam gear is on top, pointing upwards, and the line on the intake cam gear will be opposite, pointing downward. (which can’t be seen because the paper pointer finger is blocking it)
now let’s look again at the cam lobes and see what it looks like when Cylinder #2 is TDC.
you guessed it, same exact thing as the other three cylinders. VTEC lobes pointing inwards towards the spark plug tube, and theoretical 2 o’clock and 10 o’clock.
Now that you know what markings to look for that indicate which cylinder is at TDC, and you know that the firing order is 1, 3, 4, 2, you also know the fail-proof way to ensure each cylinder is at TDC by looking at the orientation of the cam lobes. Go ahead and try to freestyle; see if you can rotate the ratchet on the crankshaft a few full rotations and test yourself to see if you can guess which cylinder is at TDC. It’s also worth noting that the engine is mounted naturally at a lean, so use the engine as the reference point for which direction the marks are pointing on the cam gears, not the actual car. But if you make sure the lines on the cam gears are exactly opposite in the directions they point, and the cam lobes point the correct direction, you can’t mess this up. Remember, the cam lobes will only be pointing inward at 2 o’clock and 10 o’clock when that cylinder is at TDC.
Step 4:
Now that you know how to make each individual cylinder TDC, I’m now going to show you the process of actually adjusting the valve. I’m not going to go over each valve but rather just show you how to adjust a few valves. You will be doing 4 valves per cylinder (2 intake and 2 exhaust). The valve lash specs are.
Intake: 0.21 – 0.25mm (0.008 – 0.010 in.)
Exhaust: 0.25 – 0.29mm (0.010 – 0.011 in.)
Again, this might be different for your K-series motor; please double-check the manual. I set my intake to .008 in. and my exhaust to .010 in.
Some people say that if you can’t fit a .011-inch feeler gauge on the intake side, and you can’t fit a .012-inch feeler gauge on the exhaust side, then you don’t need to adjust that individual valve. However, I figure that you might as well adjust every valve since you have already gone to all the work to remove everything. Plus, I run the tightest clearance so that the valve can be open that millisecond more to allow for the maximum amount of air and fuel to be drawn in, thus producing better combustion. This equates to max potential power. It’s also a great opportunity to just go over each adjustment nut and make sure none are loose. When you torque the lock nut down after you have set the clearance, only torque to 14 ft/lbs. Be careful not to overtighten; you can actually snap this relatively easily.
To adjust the valve, you are going to take the feeler gauge and slide it in between the top of the valve spring/valve and the bottom of the rocker arm.
There should be some drag on the feeler gauge; if it slides in and out easily, then it’s too loose, and you will need to adjust.
Seen above, I’m trying to show the movement of sliding the feeler gauge back and forth.
You are going to adjust by using your nifty jam nut valve adjustment tool. Loosen the 10mm lock nut, then use the flat head to turn clockwise to tighten or counterclockwise to loosen the gap. The way I usually do it is, loosen the nut, then slowly turn the flathead while sliding the feeler gauge back and forth until the desired drag is on the feeler gauge. I then hold the flathead steady (not letting it rotate in either direction) as I tighten the lock nut. The drag should be pretty noticeable, but the feeler gauge shouldn’t actually be stuck or really hard to pull out or put in.
So, as you can see in the pictures above, you need to adjust the 2 intake valves (specs are 0.008 – 0.010 in.). Remember, do not over-tighten the lock nuts; the torque spec is 14 ft./lbs. for them.
Then adjust the two exhaust valves (specs are 0.010 – 0.011 in.). Remember, do not over-tighten the lock nuts; torque spec is 14 ft./lbs. for them.
Certainly, there’s no need to demonstrate the adjustment of every single valve—as that would be merely repetitive. I’ve already provided a clear visualization of each cylinder at TDC for your reference. Now, allow me to confidently outline the precise steps required to perform the valve adjustment, building on your understanding of setting each cylinder to TDC and the valve adjustment technique.
- Set cylinder #1 to TDC, adjust the 2 intake valves for cylinder#1, and the 2 exhaust valves for cylinder #1
- Set cylinder #3 to TDC, adjust the 2 intake valves for cylinder #3, and the 2 exhaust valves for cylinder #3
- Set cylinder #4 to TDC, adjust the 2 intake valves for cylinder #4, and the 2 exhaust valves for cylinder #4
- Set cylinder #2 to TDC, adjust the 2 intake valves for cylinder #2, and the 2 exhaust valves for cylinder #2
Step 5:
Reassembling everything. Now that you have adjusted a total of 16 valves, 4 per cylinder, 2 exhaust, and 2 intake per cylinder. I advise that you go through a full cycle of each cylinder at TDC, and just stick the feeler gauges in to double-check to make sure you are all within spec and that the resistance on the feeler gauge is similar for each valve, on each cylinder. At this time, I also double-check that I tightened down all the locknuts, so they don’t come loose once the engine is running because if not, this would make you very angry.
Take a clean rag and wipe away/clean all oil and debris around the head where the valve cover sits. * Pro tip is to get it as clean as possible so the valve cover gasket can completely seal, allowing no oil leaks.
Watch closely as I expertly take my index finger, wrapped in the towel, and make a precise sweep around the entire head, paying extra attention to the header side. It’s no secret that this is typically where the most oil escapes when you remove the valve cover, but with this technique, I ensure every trace is efficiently dealt with.
You also want to make sure you clean all the old Honda bond/RTV silicone off the area where the valve cover gasket meets the head.
You can see above that there is a small piece of dried Honda Bond that needs to be picked off. Make sure it doesn’t fall into the head!
At this point, it’s completely up to you if you want to get a new valve cover gasket or not. Like I said earlier, mine is fairly new, so I’m not replacing it. Eric’s is at least 5 years old, and I’m not replacing his either. It’s not so common for the actual valve cover gasket to leak. If you are reapplying new Hondabond/RTV silicone sealant, you shouldn’t need to replace the valve cover gasket. If you do decide to replace the valve cover gasket, DO NOT get one from AutoZone, Pep Boys, O’Reilly’s, etc., as they will all leak (eventually). ONLY USE the OEM one from HONDA. Here is the part number from Acura: 12030-PNC-000, which includes new valve cover grommets and washers too! If you want to search for it, it is called GASKET SET, HEAD COVER.
If you decide to reuse the valve cover gasket (like I did), just make sure you pick off all the old Hondabond/RTV silicone sealant to ensure a proper seal between the valve cover and the head. When reinstalling the gasket onto the valve cover, it can only go one way, so pay attention!
Above you can see the fresh Hondabond (grey silicone) I applied. Notice that it only needs to be in those four areas, and just a little bit will suffice. DO NOT put Hondabond around the whole thing. Also, notice how clean and dry my “old” gasket is; make sure yours looks like this too. Where the valve cover sits on the head should also be completely dry, and the valve cover gasket should be completely dry (except obviously for the four areas with Hondabond). This will ensure the best seal.
You will want to clean the oil off these as best as possible, to ensure the best seal.
Now go ahead and set your valve cover back on the head, making sure you are not pinching any lines or wires between the valve cover and the head. Now you are going to put the rubber grommets on all six holes.
Make sure that each one fits completely into the valve cover. Above, you can see the centering part of the grommet that must completely seat into the valve cover. Make sure you fully seat all six and recheck to make sure they are pushed in before you even start tightening your valve cover. Doing this will ensure the valve cover is centered, will seat properly, won’t pinch any part of the grommet (which could cause an oil leak), and once tightened, there will be even pressure all around. Once you are sure they are all seated in the valve cover properly, go ahead and put the metal washers on. Screw on the 6 nuts by hand to just get them started. (be careful these can strip easily, which could cause an oil leak because you will not be able to tighten them to the correct torque specs) Now, using a ratchet, tighten the six nuts in a star pattern (just like you would do tightening lug nuts). Tighten in a 3-step process, snugging them all down, then a bit firmer, and then the final torque spec is 7.2 ft-lbs.
- Reinstall the sparkplugs
- bolt the ground back on to valve cover
- Install the valve cover breather hose (if you have one) 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.
- Take the ratchet off the crank pulley, and re install the wheel.
And If you have a stock car
- Install the 10mm bolts holding the cruise control cable and power steering pump bracket.
- Install the intake manifold cover and its (2) 10mm bolts.
DON’T FORGET TO REMOVE THE RATCHET ON THE CRANK PULLEY BEFORE STARTING THE CAR!!!!!!!!!!!!
Here is how everything looks all back together
I hope this helps you overcome your fear of adjusting your own valves. Get out into the garage this weekend and give your car some TLC! And as always… please like, comment, share. If you have any questions, please don’t hesitate to ask; I would love to help you!
And lastly if you want to check out the S2000 (F20C) valve adjustment DIY click the link below.
This is such an amazing write up of the valve adjustment procedure! I’m surprised nobody has commented to give thanks at least! Ima be the first! Thanks for the well written info, will be adjusting my valves on my k20z3 within the next week now that I have this to reference
Thank you so much! I’m glad you found this useful, and I appreciate you taking the time to comment I love it when people interact. It’s nice to hear that what I’m doing is helpful
Hello!, i have a doubt with my k24a3 when doing this work, do you think that the minimum clearance is the most correct? I have seen other people doing it like this but…
I did 0.25 on intake and 0.30 on exhaust before reading enough, resulting on a loud sound as they are too loose, at least on the exhaust ones.
Now i am going to lower the valve clearance, but taking in mind that intake valve clearance tends to go up (in which case the valves would be OK despite of getting more clearance until 0.25), and exhaust valve clearance tends to go down, wouldn’t it be the best to adjust exhaust valves to 0.28 instead of 0.25? I know the clearance that gives the most perfomance is the closest to the minimum, but won’t them get out of range resulting in a “dangerous” situation for the before the next adjust(120k)?
Waiting for you reply.
Thanks!
Hi Dave, thanks for reaching out. after a quick search on google i was able to find these specs.
The specification is:
Int .008-.010; Exh .011-.013.
now please keep in mind this is only what I came across, and might not actually be correct since this is for a USDM motor. but the specs you mentioned above seem to be too loose for any Honda. Usually the valve lash tolerances are much tighter, which is why I believe the ones i’ve supplied are more correct. Please also note that there are usually two ways to measure valve lash. millimeters (mm) or inches (in) please make sure you are not mixing up the two.
Thank you so much
The information you provide is quite clear that provides security and excitement to perform the adjustment of the valves of my car
Thank you very much again and God bless you and everyone
Yes, I mentioned valve las instituciones mm. I wanted to say that I adjusted the clearance 0.25mm on intake(0.010 inches) and 0.30mm (0.012 inches) on exhaust.
My question is about which clearance would be the best between the allowed range for both valves, as 0.008inches clearance on intake is fine in my opinion as it usually tends to go up When the engine runs kms and the time passes by. But when we talk about the exhaust valves, if we adjust them to the minimum clearance allowed which is 0.010 inches, wouldn’t we compromise the security of valves when they start to be more tightened(when the valves become loose they sound but they won’t be hurt)? Because the exhaust Valve clearance tends to tightend.
The correct valve clearance for my k24a3 is 0.008-0.010 intake/ 0.010-0.012 on exhaust.
Thanks.
Honestly in my opinion anything withing the specs should be fine regardless of the miles (KM) on the motor. If you have them adjusted within spec and you are still hearing a noise, its possible that the timing chain tensioner may be causing the noise.
Please keep in mind it’s incredibly difficult to diagnose things over the internet. It would be much easier for me to give you better guidance if I could see/hear it in person, so the best thing i can do I just give you some basic guidance. Sorry i cant be of more help.
Allright, I just don’t wanna have any diagnose, the only thing I wanna ask or debate with you and other experts, is that if you adjust your exhaust clearance at the lower point allowed, when it passes 50 or 80.000kms your valves will be at less than that clearance because exhaust valves tend to get more tight. I could see thst when I inpected the valves st the first time, intake tends to get bigger clearance and exhaust the oppositte.
See you, nice post!!
i feel like this is all down to how well the engine is taken care of. as long as you’re within the spec’s then making it on the loser side (within spec) shouldn’t cause any issues. Thanks for reaching out.
Thank you so much! Simple put and detailed. This will definitely be my reference guide as this will be my 1st time doing a k series valve lash adjustment. I have a question, I have a K24A2 and I am running the valve seat, dual valve springs, valve retainer from a K20A Type R on both exhaust and intake side, would the specs still be 0.008/0.0010 ?
Hi! I’m so happy you liked the article. As for what lash to set yours to, I wouldn’t set it to a k20 spec because it’s still a k24 (rod length, valve size, cam specs) any other questions don’t hesitate to reach out