Join Date: Mar 2014
Location: Colorado Rockies
You can adjust both sides (in. & ex.) and the same time. As you rotate the motor watch your intake valves open and then close, the piston is now coming up to Top Dead Center (on the power stroke, of your 4 strokes). At TDC both Intake and Exhaust Valves are closed and can be adjusted at this point. Another thing to Definitely do is adjust valves while engine is COLD, I give a 24 hr. period of cool down before any adjusting due to the metal in the engine expanding with heat. If you adjust even warm valves they will be looser as the cooling metal contracts. Just my 2 cents, hope this helps.
Oh, one more thing. Were you reading the metric or the SAE print on your feeler gauges? I've seen this happen before and confuse the operator of the feeler gauge !