D17A2 Valve Set
Hello everyone! I'd like to apologize in advance for the lack of pictures as I'm making this post as I just discovered this website months after already completing this.
I thought I'd make my first post on a very basic yet important maintenance item that not many people know how to do. A valve set (or more commonly known as a valve adjustment) is the process of setting the clearance between the tip of the valve and the rocker arm. This process is usually complete at maintenance intervals suggested by the OEM manufacturer; however if your engine appears low on power, experiencing decreased fuel economy, and noisy under the valve cover then you made be in need of a valve adjustment.
While I'll be explaining this process on a D17A2 SOHC engine, the principles are still general and can be applied to many different engines. It's important to note vehicles with hydraulic lifters can not have a valve adjustment done and it uses oil to create the appropriate clearance.
The following tools required to complete a valve set is as follows:
-Basic socket and ratchet set
-Jack and jack stands
I'll do my best to make this as detailed and simple to understand. Assuming you're mechanically inclined and have performed other maintenance items or small repairs, I estimate that completing this on a D17A2 should take you no more then 2 hours.
Alright first things first you want to ensure you engine is absolutely cold, so maybe plan in advance to have the car in the garage and sitting overnight before you begin. This is important because of the expansion properties of metals which can screw your clearance numbers.
After considering that you will want to chock the back wheels, engage the parking brake, and begin lifting the front of the car. Once at a sufficient height set your jack stands under the pinch welds of the car and slowly set the car down, then ensure the car is in neutral. Now this can be skipped but this does make the process easier in my experience. Next you will want to remove the left inner fender liner. These are held in by plastic push tabs which the centres can be popped out in order to remove. Once the push tabs are removed pull back on the fender liner to expose the harmonic balancer. Continue on by disconnecting the negative terminal off the battery. Assuming your car has the factory intake(in my case I did not have one) then you'd want to remove the system. After that remove the plastic valve cover cap to gain access to the engine harness. Remove the hardware securing the engine harness to the valve and connectors off the coil packs, EGR valve, and ECT sensor in order to move it out of the way. While I have had luck with just disconnecting this, you may feel it's easier to also remove the connections off the alternator and intake in order to move the engine harness further out of the way.
Once you have sufficient room unbolt and remove the coil packs and spark plugs. While the plugs are out it's not a bad idea to inspect them and see the condition they are in and if need be, replace them. Use pliers to remove the clamp of the PCV hose, remove the hose, and then you may then begin unbolting the 5 valve cover bolts. Once the valve cover bolts are loose it may be necessary to gently tap the valve cover with a rubber mallet in order to break its seal loose. After freeing the valve cover loose you may put it off to the side. Then move towards the upper timing cover, it will be held in by 3 bolts along with the camshaft position sensor needing to be unhooked. I find it's best to pull back on the connector grommet to gain access to the connector. You can also put the timing cover off to the side. An important thing to note is you must be aware of how the engine rotates, in our case with the D17A2 it's a reverse rotation engine (viewed from the front of the engine unless specified otherwise by OEM manufacturer) which means you must rotated the harmonic balancer counter clockwise in order to avoid engine damage. While you're here I recommend fully rotating the engine to inspect the timing belt and judging if it needs replacement. If you're seeing lots of cracks well you know your timing belt will not have much longer. If you draw you attention to the back side of the camshaft sprocket you will find 2 marks 180° from each other, you will need to line those up flush with the cylinder head. Once flush you will need to find out with cylinder is at TDC in the compression stroke. To do this just simple give the rockers a wiggle on the intake and exhaust side, if both intake and exhaust wiggle you found the cylinder you will do the first adjustment on. For the D17A2 the firing order is 1-3-4-2 referring to cylinder 1 as drivers side. Your intake clearance will be 0.007"-0.009" (0.18mm-0.23mm) while the exhaust clearance is 0.009"-0.011" (0.23mm-0.27mm). In the case of the D17A2 the exhaust valves are to the front of the car and the intake valves are to the rear. If you are not doing a honda civic you can determine which valves are which by seeing the placement of the intake and exhaust manifold. Personally I always check the clearance beforehand and see how bad the clearance is. To adjust you will need to back off the lock nut and use a flat head screwdriver to turn the adjustment screw. For checking clearance I personally recommend a stepped feeler blade so theres no discrepancy in clearance but if you're using a regular feeler blade you should feel a little bit of drag on it when pulling it out from between the rocker and the valve tip. Once you have the appropriate set clearance use a wrench to tighten the lock nut and the flat head screwdriver to make sure the adjustment screw doesn't move. Double check the adjustment then proceed to torque the lock nut to 14 ft/lbs. Repeat this for all the valves in that cylinder. Then rotate the engine and watch to see when one of the camshaft marks is 90° or perpendicular to the cylinder head. This will be 180° of rotation on the harmonic balancer because the crankshaft to camshaft ratio is 2:1 in a 4 stroke engine cycle. Repeat previous instructions until you've adjust all valves in all cylinders. Carefully clean the mating surface on the head for the valve cover gasket, though not required I recommend a new valve cover gasket be installed at this time. You then can proceed to assemble the engine in reverse order of disassembly and put it back on the ground. Check your oil level then take your car out on a test drive to verify engine operation.
That's it for a valve set on a D17A2 Honda engine. If there is any questions please ask and I'll do my best to answer as quickly as I can. Hope this article helps and I appreciate some feedback in how I can improve my articles in the future! Thank you for reading! :)