Adjusting Valves on a 1988 Honda Civic DX Hatchback

November 2017. The car was running rough at idle so I inspected the spark plugs. While I was under the hood, I decided I should inspect valve clearances and adjust the valves if necessary. I have noticed a valve tap on cold mornings. The valve cover came off by removing four 10mm cap nuts and scooting accelerator and clutch cables out of their keepers. I also had to pry off the rubber hose on the left. Under the valve cover, I have indicated cylinder numbers on the spark plug holes:

I removed the timing belt cover. Here is one of two bolts holding it on:

I inspected the timing belt:

No oil on the belt, no cracks, no wear on the ridges. OK!

I removed the distributor cap (not shown) so I would be able to see which spark plug wire the rotor was pointing to. I removed the spark plugs to make it easy to turn the crankshaft. I used a 3/8" socket wrench with a 17mm 12-point socket to reach down and turn the crankshaft pulley. Some instructions say to jack up the car and remove the front left tire but I had no trouble reaching down between the wheel well and the engine (no AC in this car). I turned the crankshaft counterclockwise until the work "UP" was at the top of the camshaft gear:

The score marks on the sides of the gear aligned with the cylinder head surface and the distributor rotor pointed at spark plug wire #1. Cylinder #1 is ready for check and adjustment. Here I check between one of the intake valves and rocker arm with a feeler gauge. The clearance is supposed to be about 0.20 mm for intake valves and 0.25 mm for exhaust valves:

I adjusted the valve by loosening the lock nut on the top of the rocker arm and tightening the screw until the feeler gauge dragged slightly:

I tightened the lock nut and moved to the adjacent intake valve, then the exhaust valves. To loosed the lock nuts, I used a socket wrench to give me a little more torque and I used a 6-point socket to minimize damage to the tight lock nuts:

After adjusting the exhaust valves on cylinder 1, I turned the crankshaft 180 degrees counterclockwise which turned the camshaft 90 degrees counterclockwise putting the word "UP" towards the front of the engine. This prepares cylinder #3 for adjustment.

After cylinder three adjustment, I turned the crankshaft another 180 degrees which prepared cylinder 4 for adjustment. The word "UP" was now down.

Then another 180 degrees to prepare cylinder 2.

I went over all the lock nuts one more time with the socket wrench to make sure they were tight.

Done with the valves, I put in new NGK nickel spark plugs and took the car for a test drive. The car started like a bomb, as they used to say. The engine was definitely quieter on the short test drive and engine idled smoothly after warming up.