Loose. As valve clearance increases the valves tap more. The Honda spec is rather loose and adjusting to it will generate the typical Honda "tick." You can safely shave .002" off the Honda spec. On the 96+, going tighter will yield a check engine light.
Having valves too tight will yield low compression as they will not close all the way, drastically reducing power. Too loose and you can burn valves by running to little duration and decreasing flow through the head.
I just adjusted my valves yesterday and test drove it today. I can tell you that the valve tap increases with an increase in RPM. It's a loud tap as well. Your supposed to adjust your valves for each cylinder at TDC. TDC for each cylinder is when both the intake as well as the exhaust valves are completely closed? If that was the case - the cam top of the cam lobes would be pointed horizontally correct? I was told by a few people to adjust each side seperately when the cam lobe for that cylinder is pointed UP. I don't think this is correct is it? If this was the case, where the intake cam was pointed up, the exhaust cam would be pointing down thus the exhaust vlave would be open. I would adjust both sides at the same time.
Originally posted by Phamine I can tell you that the valve tap increases with an increase in RPM.
It should increase in frequency but not in loudness. This would be "loose" valves or valve clearance/lash.
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Your supposed to adjust your valves for each cylinder at TDC. TDC for each cylinder is when both the intake as well as the exhaust valves are completely closed? If that was the case - the cam top of the cam lobes would be pointed horizontally correct?
This is "correct" per the "recommended" way to do it. It's not how I do it (see below).
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I was told by a few people to adjust each side seperately when the cam lobe for that cylinder is pointed UP. I don't think this is correct is it?
Depends on the car (see below).
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So what is the correct procedure?
The correct procedure is in the Helms, but I don't follow it. It's good, but mine's better. You *know* what you should be doing, which is closing the intake/exhaust valves and adjusting the lash when the cams have zero lift. The problem is that when you do it at TDC you're so close to where lift starts/ends that it's easy to be a hair off and mal-adjust the valves.
In order to be safe, you should adjust the valves when the cam lobe points AWAY from the rocker arm. This is usually a little ways off from TDC on the intake and exhaust strokes. It's easy to do by sight/feel, though, regardless of the engine you're working on. In most OHC engines (single or dual) you will be adjusting when the lobe is pointed DOWN, or AWAY from the rocker.
Here's my method, hopefully someone will FAQ it:
- Let the car cool for AT LEAST 2 hours. Valve cover should be no more than about 80°F.
1) Put the car in 4th gear, e-brake on, jack the car up on the driver's side (just so the wheel lifts).
2) Remove negative battery cable, alt. cable, and valve cover.
3) Turn the driver's wheel so that the cam marks are lined up for TDC. This should bring pistons #1 and #4 to TDC.
4) The intake and exhaust valves should be closed, but the cam lobes will be pointed sideways some. Starting with cylinder #1, rotate the wheel so that the intake lobe is pointed AWAY from the rocker arm.
5) When the rocker arm is pointed away from the lobe, adjust that valve according to the sticker under the hood (or .001" to .002" tighter, if you want the valves quieter).
6) Tighten down to spec, I think about 16 ft-lbs, and recheck the clearance.
7) Rotate the driver's wheel counter-clockwise about 90°. This should put the #3 intake lobe in the same position (opposite the rocker arm) as the #1 was. MAKE SURE the lobe is 180° from the rocker. Adjust, tighten, and recheck.
8) Repeat step 7 until you do 1 - 3 - 4 - 2 IN THAT ORDER. Once you are done with the #2 intake, the #1 exhaust should be almost where you want it. Rotate the wheel so that the lobe is away from the rocker arm, then repeat the process again, 1 - 3 - 4 - 2 until you get them all.
Button it back up and you should be in business.
I can't stress how important it is to do this process when the engine is cold (I usually let it sit overnight) and to recheck after tightening the locknuts. It's almost an art, getting it set right so that it doesn't move when you torque it, or "pre-setting" it so when you torque you don't go too tight.
Sears sells a "bent" feeler gauge that makes the process a little easier.
Originally posted by marcucci The problem is that when you do it at TDC you're so close to where lift starts/ends that it's easy to be a hair off and mal-adjust the valves.
I spent so much extra time trying to be "exactly" at TDC, that I bet I could shave off half the time or more by doing it your way. Nice tip Todd.
"In order to be safe, you should adjust the valves when the cam lobe points AWAY from the rocker arm. This is usually a little ways off from TDC on the intake and exhaust strokes. It's easy to do by sight/feel, though, regardless of the engine you're working on. In most OHC engines (single or dual) you will be adjusting when the lobe is pointed DOWN, or AWAY from the rocker. "
what do u mean, could u elaborate?
i can NEVER get the valve settings right and my valves tap as the rpm increases at well b/c
"The problem is that when you do it at TDC you're so close to where lift starts/ends that it's easy to be a hair off and mal-adjust the valves."
i totally agree with that!
be elaborate on this procedure so i can get it adjusted right.
thx
Todd...u are THE MAN. I wish all mechanics "think" like you. But then, I guess that's why you're an engineer.
__________________
I'M ON MY THIRD PRELUDE!!!
1.93' Prelude Si w/ sh*t load of mods - Got Stolen in 96', found in East Los Angeles with nothing
2.97' Prelude Typesh w/ a few mods - Got Hit in 99', severe front end damage
3.93' Prelude VTEC w/ a few mods - What I Got Now and I am keeping this one! (knock on wood)
Just for clarification:
If the cam lobe is AWAY from the rocker, no pressure is applied to the rocker, therfore the valve is closed. The correct lash can be adjusted. Is this accurate?
Originally posted by danalude Just for clarification:
If the cam lobe is AWAY from the rocker, no pressure is applied to the rocker, therfore the valve is closed. The correct lash can be adjusted. Is this accurate?
Away from the rocker as in the cam lobe pointed up? I am guessing you can do that since about half of the cam profile alows the valve to be closed.
Originally posted by danalude Just for clarification:
If the cam lobe is AWAY from the rocker, no pressure is applied to the rocker, therfore the valve is closed. The correct lash can be adjusted. Is this accurate?
Yes, this is accurate. This should answer SSgohan and Jake, too.
To be honest, I can't remember on the Prelude which direction the lobe needs to be (up or down), since I haven't adjusted on in over a year. I'll have to look at the head I have on my bench and see how it goes.
Jake, you want to adjust on #1 or #4, when the valves are closed. You probably can't adjust them on #2 or #3, since the valves will be open and you probably can't adjust them enough to get clearance. You certainly DON'T want to adjust them on strokes 2 or 3, though!
It appears that the #1 cylinder(closest to the timing belt) has a exhaust rocker arm that snaps each time when the cam lobe is compressing the valve spring. I've tried to remedy it by removing the adjusting nut and adjusting it to loose to tight - I still have the problem with this rocker arm snapping.
Also, the rocker arm pivot seems to lean more into the camshaft lobe. They actually touch, and once they do touch, it snaps back into position.
Also, when the exhaust valve is fully closed(no pressure on the spring) - the working rocker arm would have some play while the snapping rocker arm would have no play(can't wiggle)
Here are some pictures:
*notice the lower rocker pivot closer than the other
*notice the pivot touching
*after it touches some more - it will snap back into position
I don't know where to start to alleviate this problem - Any Ideas?
BTW: My valves were loose and marcucci's method is pretty precise in the matter of adjusting valve clearance.
marcucci - i will readjust my valves this weekend again with ur method. thx for the info.
my valve tap as the rpm increases - could it be that my valves stem are worn or a rough idle problem???
BTW-when i hook up a vacuum gauge to my car-the needle will vibrate very very little.
Originally posted by SSgohan
my valve tap as the rpm increases - could it be that my valves stem are worn or a rough idle problem???
BTW-when i hook up a vacuum gauge to my car-the needle will vibrate very very little.
I suspect the valve tap is just valve tap- it's just the adjustment. We'll find out, just be sure you adjust your valves cold, and pull back maybe .001" or .002" on the adjustment. To be super-precise, adjust them so you can put the feeler in you want but NOT the next one larger. You don't need to make the feeler super-tight, just enough to put some drag on it (try the larger feeler and see).
What do you mean/intend by the vacuum gauge? That just tells me you don't have a leak. I wouldn't expect you to have any problem... though I'd have to hear the "tap" to be sure. Sounds to me so far like the valves are just set a little too loose.
Phamine, what are you talking about?! I don't follow from your description or the pictures. How does the exhaust rocker "snap?"
I suspect the valve tap is just valve tap- it's just the adjustment. We'll find out, just be sure you adjust your valves cold, and pull back maybe .001" or .002" on the adjustment. To be super-precise, adjust them so you can put the feeler in you want but NOT the next one larger. You don't need to make the feeler super-tight, just enough to put some drag on it (try the larger feeler and see).
What do you mean/intend by the vacuum gauge? That just tells me you don't have a leak. I wouldn't expect you to have any problem... though I'd have to hear the "tap" to be sure. Sounds to me so far like the valves are just set a little too loose.
Phamine, what are you talking about?! I don't follow from your description or the pictures. How does the exhaust rocker "snap?"
Marcucci - The pivot of attached to the rocker arm was hitting the cam lobe. It was not clearing the top of the cam lobe. You can see by the picture that the pivot was actually hitting the cam lobe. That was the cause of my loud tap coming from my engine the first time I adjusted it. I alleviated the problem by readjusting the pivot according to the valve clearance.
I too have the problem of valve tap as ssgohan has. It would only tap AFTER 3000 RPMS. Anything below 3000 RPMS it's very quiet - no sign of vavle tap. It's only after 3000 RPMS that the valves would tap and would increase tapping according to RPM. again, I am just going to ask again to be sure - would this tapping be tight valves or loose since it's only after 3000 rpms?
This is how I adjusted the valves. I used a go and no go method of measuring the clearance.
ie. My valve clearance spec for the exhaust valves is .006mm-.007mm. I would make sure that .006 would go through while .007mm would not. That way, I know the valve clearance is within the specification.
Here are a few pictures of how i did it.
*This is the adjusment when it's TDC - notice the cam is pointed away from the rocker arm. It's the same thing for the exhaust - it points away from the rocker arm.
*Away from the rocker arm - right a little off TDC.
*this is when the cam lobe is facing up.
I adjusted all the valves to all 3 points. Most of the adjustments were the same for most of the valves. Some were off. If they were off, I would just keep the TDC adjustment for that particular valve.
So what did I do wrong to get this tap? I adjusted all the valves to factory spec, torqued all the adjusment nuts to factory spec.
Originally posted by Phamine
The pivot of attached to the rocker arm was hitting the cam lobe. It was not clearing the top of the cam lobe. You can see by the picture that the pivot was actually hitting the cam lobe. That was the cause of my loud tap coming from my engine the first time I adjusted it. I alleviated the problem by readjusting the pivot according to the valve clearance.
I don't know what you mean by pivot, unless you're talking about the rocker arm itself. If that's smacking the lobe, that's a serious problem. I can't think of anything the lobe could hit like that. If so, I would suspect damage on one of them.
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I too have the problem of valve tap as ssgohan has. It would only tap AFTER 3000 RPMS. Anything below 3000 RPMS it's very quiet - no sign of vavle tap. It's only after 3000 RPMS that the valves would tap and would increase tapping according to RPM.
This is now, after you did your clearance adjustment?
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again, I am just going to ask again to be sure - would this tapping be tight valves or loose since it's only after 3000 rpms?
If it's ONLY after 3k that you hear the noise I would think something is wrong. If it's like an on/off switch then something is definitely not right. If it just get's louder... well, how much louder does it get?
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This is how I adjusted the valves. I used a go and no go method of measuring the clearance.
It sounds like you did it right.
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*This is the adjusment when it's TDC - notice the cam is pointed away from the rocker arm. It's the same thing for the exhaust - it points away from the rocker arm.
My only concern is that it looks like it's pointed away 90?‹ or so. There's a lot of duration in VTEC, you want to be sure the lobes are 180?‹away from the rocker arm pad to be safe. Look at where the lobe "wipes" the pad (where the pad is tangent) and be sure to put the lobe opposite of that. You might be doing it, it might be just the picture (or my interpretation ).
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I adjusted all the valves to all 3 points.
What do you mean by "all 3 points?"
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Most of the adjustments were the same for most of the valves. Some were off. If they were off, I would just keep the TDC adjustment for that particular valve.
What do you mean by keeping the "TDC adjustment for that particular valve?"
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So what did I do wrong to get this tap? I adjusted all the valves to factory spec, torqued all the adjusment nuts to factory spec.
Factory spec taps kind of loud. I'd suggest shaving .001 or .002 off of factory to quiet things down and improve power a hair. I'm not sure what's "wrong" but please answer my questions above- I might be missing something, but it also might be a "procedural" problem.
I don't know what you mean by pivot, unless you're talking about the rocker arm itself. If that's smacking the lobe, that's a serious problem. I can't think of anything the lobe could hit like that. If so, I would suspect damage on one of them.
Yes, that's what I mean. It turned out that I just had to adjust the rocker arm itself so that it won't "pivot in" as much when the top of the cam lobe is pushing down on the rocker.
This is now, after you did your clearance adjustment?
Yes, this is now. My first attempt to adjust the valves was the case where the rocker arm was hitting the cam lobe.
If it's ONLY after 3k that you hear the noise I would think something is wrong. If it's like an on/off switch then something is definitely not right. If it just get's louder... well, how much louder does it get?
Yes, it's just like a switch. I have an H23 by the way. Once it does start tapping - it does not get louder than initially. It's as loud as a bad exhaust rattle.
My only concern is that it looks like it's pointed away 90?‹ or so. There's a lot of duration in VTEC, you want to be sure the lobes are 180?‹away from the rocker arm pad to be safe. Look at where the lobe "wipes" the pad (where the pad is tangent) and be sure to put the lobe opposite of that. You might be doing it, it might be just the picture (or my interpretation ).
The first picture where the top of the cam lobe is facing towards the direction of the intake manifold is how the helms manual describes to perform a valve adjustment. Is this what you mean by 90 degrees away from the rocker? The first picture is where the cylinder is at the compression stroke(TDC). Also, both of the exhaust and intake valves are closed.
•What do you mean by "all 3 points?"
•What do you mean by keeping the "TDC adjustment for that particular valve?"
This may be a procedural problem. I adjusted at TDC(both intake and exhaust cam lobes are facing away from the rocker). The second adjustment is when the cam lobe is 135 degrees from the rocker arm "pivot"(2nd pic). The third adjustment is at 90 degrees from the rocker "pivot"(3rd pic). If the adjustments for the 2nd pic and 3rd pic did not agree with the the TDC adjustment(1st pic), I kept the TDC adjustment.
Factory spec taps kind of loud. I'd suggest shaving .001 or .002 off of factory to quiet things down and improve power a hair. I'm not sure what's "wrong" but please answer my questions above- I might be missing something, but it also might be a "procedural" problem.
I'm going to redo the valves and make them tighter by .001 as you've stated this weekend. I just can't figure out why it only taps after 3000 RPMS and not during the entire RPM range.
Originally posted by phamine
Yes, that's what I mean. It turned out that I just had to adjust the rocker arm itself so that it won't "pivot in" as much when the top of the cam lobe is pushing down on the rocker.
How did you adjust the rocker? There should be no adjustment that I'm aware of, other than the valve clearance. If it is/was hitting I would think that there's a serious problem in your head.
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Yes, it's just like a switch. I have an H23 by the way. Once it does start tapping - it does not get louder than initially. It's as loud as a bad exhaust rattle.
This is very very bad. You have a serious problem that should be attended to. I'm afraid I can't help without being able to look at the head, though. I would find someone local who can help and go from there. The noise is definitely not normal.
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The first picture where the top of the cam lobe is facing towards the direction of the intake manifold is how the helms manual describes to perform a valve adjustment. Is this what you mean by 90 degrees away from the rocker? The first picture is where the cylinder is at the compression stroke(TDC). Also, both of the exhaust and intake valves are closed.
This is how they say to do it, but it's easy to be a little off and end up with a little more or less valve lash than necessary. With my method above I'd suggest pointing the lobe completely opposite of the rocker pad so you are sure that you are measuring at 0 lift. I'm not sure this would be related to your problem, though, it sounds a lot more serious than a mal-adjusted valve.
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I adjusted at TDC(both intake and exhaust cam lobes are facing away from the rocker). The second adjustment is when the cam lobe is 135 degrees from the rocker arm "pivot"(2nd pic). The third adjustment is at 90 degrees from the rocker "pivot"(3rd pic). If the adjustments for the 2nd pic and 3rd pic did not agree with the the TDC adjustment(1st pic), I kept the TDC adjustment.
The middle pic is where you want them. Why did you adjust in 3 different spots? The Honda measurement, if you are *perfect* should match the measurement in the middle picture. If it's off, I'd go with the one in the middle pic. I don't think this is your problem, though, the noise should not come and go, it should be constant (only varying in speed with RPM, not intensity).
I'd look at it again and see if there is anything that is scoring (like where that rocker was striking) and try and figure out how the rocker was hitting. I'm still curious to know how you adjusted the rocker.
•How did you adjust the rocker? There should be no adjustment that I'm aware of, other than the valve clearance. If it is/was hitting I would think that there's a serious problem in your head.
•I'd look at it again and see if there is anything that is scoring (like where that rocker was striking) and try and figure out how the rocker was hitting. I'm still curious to know how you adjusted the rocker.
Alright, the adjustment on the rocker is 'adjustable'. The screw on the rocker is threaded. It could move up or down - it just depends how you rotate the screw. It's just like a regular wood screw or any kind of screw. I loosened the adjusting nut and screwed the screw in. At this point, the screw is in. I think it's similar to a lever. You screw the screw in, the rocker moves up into the cam lobe thus making the clearance tighter. For some reason, it also changed the angle that the rocker pivot. It was how the pivot was angled that caused the cam lobe to touch the pivot. I forgot to mention that there wasn't any play with that particular rocker at all.You wouldn't be able to wiggle it as you would be able to do so with the other rockers at TDC. My guess is that the rocker sensed that there was pressure from the cam lobe.
I hope you're wrong about the head marcucci. I'm going to do another valve adjustment this weekend and see if that would alleiviate the problem. I'll even retard my timing this time. I don't know if a valve adjustment would have anything to do with timing. - I'll try it anyway. If this time doesnt cure it - off to the shop it goes. I'll keep you posted.
Originally posted by Phamine
Alright, the adjustment on the rocker is 'adjustable'. The screw on the rocker is threaded. It could move up or down - it just depends how you rotate the screw.
So you're just talking about the valve lash adjuster, what you adjust to adjust the valves, right? That's what it sounds like. So did you adjust that valve so that the rocker stopped contacting the cam, or did you just set it to spec? If you set it a lot looser than spec, that might be causing the (or at least a) problem. Much looser than spec and you can burn valves as well as hurt power, maybe even imbalance things enough to cause all kinds of weird problems.
I think you know enough of what you're doing to know WHAT you are doing in terms of setting the valve adjustment. You seem to have the concept down which makes me think it's not what you're doing. You should only need to adjust the valve lash with the cam lobe in Honda's position or pointing away from the rocker, you shouldn't need to adjust (or adjust for) anything else. That's why I say you might have something seriously wrong. If you adjusted the one rocker too loose or by some other spec, all bets are off.
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I hope you're wrong about the head marcucci. I'm going to do another valve adjustment this weekend and see if that would alleiviate the problem. I'll even retard my timing this time. I don't know if a valve adjustment would have anything to do with timing. - I'll try it anyway. If this time doesnt cure it - off to the shop it goes. I'll keep you posted.
I hope so too! You shouldn't need to adjust your timing, but I'd set it back to stock (if advanced) to be safe. Once you get the tapping eliminated you can bring the timing back in.
You *know* what you should be doing, which is closing the intake/exhaust valves and adjusting the lash when the cams have zero lift. The problem is that when you do it at TDC you're so close to where lift starts/ends that it's easy to be a hair off and mal-adjust the valves. 
