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    #1

    Valve Adjustment Gap Question

    So with 230-240K on this motor and no idea about past history, I figure adjusting the valves would be something I could do.

    When I went to adjust the valves the .25mm feeler gauge wouldn't really go in between the eccentric and the valve. I didn't mess with these and figured I would just adjust the loose ones to match the other ones.

    My question is:

    If the gap is small already, is there any need to adjust?
    Can the gap be too small?
    What would happen if this were the case?

    I assume a large gap is worse than a small one correct?

    I'm just wondering because the motor didn't seem to make any valve clicking noises or anything like that. I haven't put it back together so if anyone thinks it's a good idea to increase the gap on the "tight" valves, I can still do so. I would just imagine over time the gap increases and thus the need for an adjustment. no?
    Last edited by hotballs; 05-07-2009, 06:04 PM.
    Tags: None
    #2
    If the "gap" (Lash) gets too "small" (tight) it's a bad thing. The valves may not seat properly and burn.

    Especially the exhaust valves because the only cooling the valve head really gets is via transfer to the seat when they are closed.

    They really need to be precisely .25mm cold.
    I'm Not Right in the Head | Random Rants and other Nonsense1st Order Logic Failure: Association fallacy, this type of fallacy can be expressed as (∃x ∈ S : φ(x)) → (∀x ∈ S : φ(x)), meaning "if there exists any x in the set S so that a property φ is true for x, then for all x in S the property φ must be true".

    Comment

      #3
      Sometimes I have trouble getting the gauge in too, try cleaning the valve tips?

      Is the motor cold, like stone cold?
      1989 cirrisblau-metallic 325i

      Comment

        #4
        Originally posted by SpecM View Post
        Sometimes I have trouble getting the gauge in too, try cleaning the valve tips?

        Is the motor cold, like stone cold?
        I wouldn't say it was stone cold, I'll do it again in the morning.

        I was just wondering if over time without an adjustment for many many miles would the gap become more tight or loosen up?

        Comment

          #5
          They can do one or the other or both. Seems to me like short hop drivers loosen them up and long haul cruisers tighten them.
          I'm Not Right in the Head | Random Rants and other Nonsense1st Order Logic Failure: Association fallacy, this type of fallacy can be expressed as (∃x ∈ S : φ(x)) → (∀x ∈ S : φ(x)), meaning "if there exists any x in the set S so that a property φ is true for x, then for all x in S the property φ must be true".

          Comment

            #6
            Originally posted by Liam View Post
            They can do one or the other or both. Seems to me like short hop drivers loosen them up and long haul cruisers tighten them.
            Hmm, that would make sense being that my car has spent most of it's life in Los Angeles. The idle stays right around 800 with little blips here and there. Like I said there is no clicking noises, but I'll loosen them up a bit to fit the .25mm gauge.

            And what's the rule of thumb for the gauge? On the pelican site they talk about a "slight drag." Well it seemed to have a "slight drag" on any gauge I put in there between .20mm-.30mm.

            Do you put the .25mm feel gauge between the eccentric and valve and rotate the eccentric so the gauge doesn't move then tighten it down or what?

            Comment

              #7
              This is a tough one to explain, the gauge should slide through and you have to "feel" that it is right... a "slight drag"

              I put the .25 in and roll the eccentric on it (using the little special tool that goes in the hole) with just the weight of my finger. Tighten the nut and slide the .25 through to re check.

              ( I can almost see your blank stare)
              I'm Not Right in the Head | Random Rants and other Nonsense1st Order Logic Failure: Association fallacy, this type of fallacy can be expressed as (∃x ∈ S : φ(x)) → (∀x ∈ S : φ(x)), meaning "if there exists any x in the set S so that a property φ is true for x, then for all x in S the property φ must be true".

              Comment

                #8
                Right, I was there this afternoon rotating that thing back and forth thinking, ok is this it? or is this it? hmm... like most things in life, once you're good at them you don't really know how to explain how to do it, you just do it.

                Well I'll use a slight pressure against the gauge and tighten them down, see where it goes from there. Thanks Liam.

                Comment

                  #9
                  Originally posted by hotballs View Post
                  Right, I was there this afternoon rotating that thing back and forth thinking, ok is this it? or is this it? hmm... like most things in life, once you're good at them you don't really know how to explain how to do it, you just do it.

                  Well I'll use a slight pressure against the gauge and tighten them down, see where it goes from there. Thanks Liam.
                  Just get it so the gauge will go through after the lock nuts are tight (and don't torque the shit out of them, it can damage the rocker).
                  I'm Not Right in the Head | Random Rants and other Nonsense1st Order Logic Failure: Association fallacy, this type of fallacy can be expressed as (∃x ∈ S : φ(x)) → (∀x ∈ S : φ(x)), meaning "if there exists any x in the set S so that a property φ is true for x, then for all x in S the property φ must be true".

                  Comment

                    #10
                    One could also define the "slight drag" as still being able to move the feeler gauge, but with some resistance.

                    I find that if I can remove the feeler after tightening the eccentric it should be ok. Additionally, you should be able to re-insert the gauge afterwards as a double check. (I've seen far too many dented and creased gauges from people trying to force it out after over tightening the cam.)

                    Comment

                      #11
                      Originally posted by jmc1590 View Post
                      One could also define the "slight drag" as still being able to move the feeler gauge, but with some resistance.

                      I find that if I can remove the feeler after tightening the eccentric it should be ok. Additionally, you should be able to re-insert the gauge afterwards as a double check. (I've seen far too many dented and creased gauges from people trying to force it out after over tightening the cam.)

                      Stated very well.
                      I'm Not Right in the Head | Random Rants and other Nonsense1st Order Logic Failure: Association fallacy, this type of fallacy can be expressed as (∃x ∈ S : φ(x)) → (∀x ∈ S : φ(x)), meaning "if there exists any x in the set S so that a property φ is true for x, then for all x in S the property φ must be true".

                      Comment

                        #12
                        Another way to determine if you have the correct amount of drag is to take out the .25mm one and try to install the next largest and then the next smallest shim.

                        The next largest should not fit.
                        The next smallest should easily slide in.

                        Comment

                          #13
                          The easiest way to adjust the valves is by using a spring tool in the eccentric holes. With one of those you place the feeler between the valve and eccentric, get a generous bend in the tool and tighten the lock bolt. The clearance comes out perfect every time. The one I have was purchased from BavAuto years ago. Dunno if they still sell that tool.
                          The car makes it possible, but the driver makes it happen.
                          Jim Levie, Huntsville, AL

                          Comment

                            #14
                            Once you've got the hang of adjusting the valves cold - give it a shot with the motor hot. I've done my last few adjustments that way, it ends up sounding like a new motor instead of a "clack clack clack". You gotta be quick though because as the engine cools the adjustments will change.
                            Build thread

                            Bimmerlabs

                            Comment

                              #15
                              Originally posted by twright View Post
                              Another way to determine if you have the correct amount of drag is to take out the .25mm one and try to install the next largest and then the next smallest shim.

                              The next largest should not fit.
                              The next smallest should easily slide in.
                              Alright, sounds simple enough. I mean they are supposed to be pretty specific measuring tools.

                              Thanks, all very good information.

                              Comment

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