Acura/Honda Valve Clearance Adjustment


I have a 2014 Acura TSX, 4 Cylinder 2.4 L engine. I’m trying to the valve clearance adjustment. I’ve done this before on a Honda, with the engine completely removed from the car. I had the luxury of getting up and close at eye level with the valve train, with nothing else in the way. It was not very difficult.

However, with the engine in the car, this seems very tedious and time consuming. Other things are in the way, so I can’t get up and personal with the engine. Not only that, the engine is at a slight angle in the car, making the exhaust valves, difficult to access and visualize even with a mirror.

If it is out of specification by 0.001 mm, I’m supposed to adjust the screw after loosening the nut. But it seems very fine adjustments of the screw is required. I don’t have the fine hand coordination to adjust the screw ever so slightly, to result in the gap adjusting by 0.001 mm. It seems like it’s necessary to adjust the screw by maybe less than 1 degree?? to get a difference of 0.001 mm?

Is there an easier way of doing this, or any hints and tips?

I’ve done valve clearance adjustments on a non-acura/honda engine, and I fine the process much easier. Yes, you have to remove the valve lifter buckets and take that extra step, but the fine adjustment of the screw is a bit difficult for me on Acuras/Hondas.

Not 1 degree. There is a tolerance, you just need to be between min and max.

As usual you are overthinking this. I’ve done this in-car with my S2000. Anything to narrow, open the clearance, insert a feeler gauge, snug the screw, tighten tbe locknut. Check clearance. Rotate the engine, repeat.

You’ve done it before out of the car, it is just a little more tedious in the car. Just do it.

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The engine valves don’t know or care if the engine is in the car or on a stand while adjusting them… May be a little harder to do/get too, but that’s on you not the engine…

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There is no excuse whatsoever for honda not to be using automatic hydraulic valve adjustment. And frankly, if you don’t have the fine hand control necessary to do this correctly, you should be taking it to a prifessional!

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I believe that your spec is incorrect. I believe it should be approximately 0.2 mm, much, much larger than the .001 mm you discuss. If you found .001 somewhere, it was probably .001 INCH.
Take a look at YouTube for full advice.

Found this:
Valve Clearance Spec: Intake: 0.21 - 0.25 mm (0.008 - 0.010 in) Exhaust: 0.25 - 0.29 mm (0.010 - 0.011 in)

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Toyota uses shims to adjust lash… Hydraulic lifters are more prone to fail and not be as consistent especially on OHC engines … Maybe since they both have some of the longest lasting engines on the road they might be on to something… But I agree, I’d rather not have to mess with adjusting them…

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Through at least the end of the 1960’s, Chrysler Corporation had the longest lasting engines on the market, and the slant six was at the head of that pack. I know that engine (at least through 1968) had solid lifters. Sometime subsequent to 1968, that engine was switched to hydraulic lifters without affecting its legendary reliability.

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My 50 year old truck has hydraulic lifters, never a problem. My 30 year old Corolla has solid lifters, never had a problem from them either; but some are near to needing a shim change.

So, the intake spec might be written as 0.23 mm +/- 0.02 mm as I wrote above. This is far higher than the 0.001 mm the OP stated.

The intake spec could also have been written as 0.009 +/- 0.001 inches, which shows the where the OP got the 0.001…but he wrote it as mm.

Didn’t NASA make the same error on the Hubble telescope, slightly more expensive!

The fault on that one was actually not NASA but a contractor.

Both actually. NASA doesn’t award a contract and show up later to take possession of whatever they bought. Both work closely together during manufacturing. The data showing a grinding error was available, but was not completely reviewed due to time constraints. That data was still useful because it gave the group designing the corrector mirrors an idea of the astigmatism they needed to grind into the corrector mirrors to provide a more perfect image. Note that th images from HST before correction were not terrible, but did not provide the fine detail initially desired.

The mirrors on the Hubble were exactly to spec, on the ground. What had not been taken into consideration was how much gravity had distorted the mirrors on the ground. When it got into space and a zero gravity situation, the mirrors were no longer distorted by gravity.

This was the first time a telescope of that size was put into space so there was no precedence for this. No one had thought about gravity distorting the mirrors. This is what they call a “lesson learned”.

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The explanation I’ve always heard for the “Hubble-problem” is that the individual design drawings for both major parts (telescope and image sensor) were ambiguous about where the reference point was located. The two parts were done by separate groups in separate locations. One group assumed the reference point was one place, and the other group assumed it was another place. The result was the telescope’s optics focused perfectly but not at the point where the image sensor was located.

The reason the problem wasn’t discovered pre-launch, earth’s gravity makes it possible to test while both parts are connected on the ground.

I would be surprised if the telescope and the balance of the instrument were misaligned enough to cause a problem. Telescope alignment had been going on for a while when this one was built. I was told that Lockheed had been building similar telescopes for DoD and that is a big reason why they got the contract. In any case, the official reason is that the primary mirror was ground incorrectly and I’ve never heard anything different from people that worked on the first servicing mission, who’s primary goal was to correct the astigmatism in the primary mirror.

The image sensor must be located exactly at the optical focal point for the image to be in focus. When grinding optical mirrors it is common to use specialized measuring gadgets called “null correctors”, or “null collectors”, something like that. Perhaps the problem was that during the mirror grinding they didn’t place the measuring gadget at the correct distance.

Here’s what happened:
" A commission headed by Lew Allen, director of the Jet Propulsion Laboratory, was established to determine how the error could have arisen. The Allen Commission found that a reflective null corrector, a testing device used to achieve a properly shaped non-spherical mirror, had been incorrectly assembled—one lens was out of position by 1.3 mm (0.051 in).[90] During the initial grinding and polishing of the mirror, Perkin-Elmer analyzed its surface with two conventional refractive null correctors. However, for the final manufacturing step (figuring), they switched to the custom-built reflective null corrector, designed explicitly to meet very strict tolerances. The incorrect assembly of this device resulted in the mirror being ground very precisely but to the wrong shape. A few final tests, using the conventional null correctors, correctly reported spherical aberration. But these results were dismissed, thus missing the opportunity to catch the error, because the reflective null corrector was considered more accurate.[91]

The commission blamed the failings primarily on Perkin-Elmer. Relations between NASA and the optics company had been severely strained during the telescope construction, due to frequent schedule slippage and cost overruns. NASA found that Perkin-Elmer did not review or supervise the mirror construction adequately, did not assign its best optical scientists to the project (as it had for the prototype), and in particular did not involve the optical designers in the construction and verification of the mirror. While the commission heavily criticized Perkin-Elmer for these managerial failings, NASA was also criticized for not picking up on the quality control shortcomings, such as relying totally on test results from a single instrument.[92]"

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