Valve clearance way off on '02
05-20-2002, 02:37 AM
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Valve clearance way off on '02
After reading a thread on valve clearances (I can't find the thread), I decided to check mine. I have about 6000 miles on it, so I figured it would be a good idea to see how it was breaking in.
I let the car cool over night, popped open the Helm's manual, and followed its procedure to record and adjust the before / after clearances. I was really surprised to find that every valve had significantly less clearance than it was supposed to. Most of the intake valves had clearances of .005" (spec: .008-.010), but 3 had even less than that (my smallest feeler guage is .005, and it wouldn't slide through at all). Most of the exhaust valves had clearances of .006 (spec: .010-.011), but 1 had less than .005. I very meticulously adjusted all of them to .008 and .010, rotated the crank 720 degrees, and rechecked them.
After warming the engine up, I noticed that the idle was much smoother (not any quieter), and the vibration that I could normally feel at a stop light, was completely gone. The surprising thing is that the sound from my AEM intake changed drastically. It seems to have gotten louder below VTEC, and quieter above VTEC. I have always liked the sound that it made, but it is now even better. Previously, when VTEC kicked in, it had a sort of raspy, mechanical sound (I thought it sounded good, but my wife thought it sounded like something was wrong with it), but now sounds more mellow and "musical". One other difference is that the power used to drop off significantly above 8500 RPMs, but I don't think it does anymore. Aside from that, I can't tell if it is more or less powerfull.
I was guessing that reducing the clearances would increase torque (increasing turbulance by decreasing lift and duration) and decrease HP (reducing total airflow by decreasing lift and duration). Although, I guess it is possible that I could have increased HP if the valves weren't seating properly, or if the mismatched valve lift and duration caused aukward flow patterns within each cylinder.
I wish I would have had the forethought to do a before / after dyno test. Oh well, I did recently do some rolling start drag races with another S2000 owner, and we were pretty even. I will see if he will do it again, so I can see if it is any faster or slower.
I let the car cool over night, popped open the Helm's manual, and followed its procedure to record and adjust the before / after clearances. I was really surprised to find that every valve had significantly less clearance than it was supposed to. Most of the intake valves had clearances of .005" (spec: .008-.010), but 3 had even less than that (my smallest feeler guage is .005, and it wouldn't slide through at all). Most of the exhaust valves had clearances of .006 (spec: .010-.011), but 1 had less than .005. I very meticulously adjusted all of them to .008 and .010, rotated the crank 720 degrees, and rechecked them.
After warming the engine up, I noticed that the idle was much smoother (not any quieter), and the vibration that I could normally feel at a stop light, was completely gone. The surprising thing is that the sound from my AEM intake changed drastically. It seems to have gotten louder below VTEC, and quieter above VTEC. I have always liked the sound that it made, but it is now even better. Previously, when VTEC kicked in, it had a sort of raspy, mechanical sound (I thought it sounded good, but my wife thought it sounded like something was wrong with it), but now sounds more mellow and "musical". One other difference is that the power used to drop off significantly above 8500 RPMs, but I don't think it does anymore. Aside from that, I can't tell if it is more or less powerfull.
I was guessing that reducing the clearances would increase torque (increasing turbulance by decreasing lift and duration) and decrease HP (reducing total airflow by decreasing lift and duration). Although, I guess it is possible that I could have increased HP if the valves weren't seating properly, or if the mismatched valve lift and duration caused aukward flow patterns within each cylinder.
I wish I would have had the forethought to do a before / after dyno test. Oh well, I did recently do some rolling start drag races with another S2000 owner, and we were pretty even. I will see if he will do it again, so I can see if it is any faster or slower.
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