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Setting Valve lash (clearance) "on the bench"

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    #16
    Originally posted by johnl View Post
    This wouldn't explain why rotating the camshaft in either direction would be so difficult as to cause the bolt to break.
    Perhaps the cam caps were tightened down too hard? OP, did you clean, lube and torque them properly? Were there any points in the rotation where the cam spun freely or was there always resistance the whole way around?


    - 1993 Accord LX - White sedan (sold)
    - 1993 Accord EX - White sedan (wrecked)
    - 1991 Accord EX - White sedan (sold)
    - 1990 Accord EX - Grey sedan (sold)
    - 1993 Accord EX - White sedan (sold)
    - 1992 Accord EX - White coupe (sold)
    - 1993 Accord EX - Grey coupe (stolen)
    - 1993 Accord SE - Gold coupe (sold)
    Current cars:
    - 2005 Subaru Legacy GT Wagon - Daily driver
    - 2004 Chevrolet Express AWD - Camper conversion

    Comment


      #17
      Originally posted by cp[mike] View Post
      Perhaps the cam caps were tightened down too hard? OP, did you clean, lube and torque them properly? Were there any points in the rotation where the cam spun freely or was there always resistance the whole way around?
      The cam was lubed with the Web Cam's lube that Bisi provided with the parts. Everything was cleaned and lubed by the shop, although I now regret not asking if they had torqued everything correctly. This was, as they admitted, their first ever F series head, but they had done many b series and d series heads before (I even saw one on their bench).

      When the shop owner was showing me how he thought I should lash the valves (he spoke with certainty), the cam rotated with only some resistance, an amount that didn't alarm him or me at all. Even at home, when the screws in the rocker arms and the lock nuts are all loose, the cam rotates with that same amount of manageable resistance. After I started going through the sequence and setting clearances, then it became progressively harder to rotate the cam. Furthermore, only when starting at TDC, rotating 270 degrees clockwise, and setting clearances in the firing order (1-3-4-2), did it become too hard to rotate with my ratchet, and this happened precisely after setting cylinder 4 and moving to cylinder 2. I got it to rotate through 180 degrees, so it was at TDC, and that is where it would not go further, except to twist and snap the bolt in 2 pieces.

      "Snap' is really the wrong word for what happened. I noticed the cam wasn't turning, but my ratchet was. I quickly took the bolt out entirely to see if it was okay. Most threads looked normal, but about four rows of threads near the head were quite spread out. My next thought was idiocy, "Well, I guess it's a special bolt with two levels of threads". I put it back in, tried to rotate again and that's when it split into two.

      Johnl, I have those springs in there because I was recommended to put them in there along with the Bisi Level 2 cam I was purchasing. This is a drag race project, so I will be pushing it to the rev limiter, but I do have to drive it to the track, a two hour trip.

      When ordering the cam with Janet on the phone, I decided to have her order a new cam from Honda instead of send mine as a core. I hope this isn't a, what I will call, "wagon r" cam. I'm starting to get worried, though.
      *** Think of others before thinking of yourself. ***
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      MRT
      Selling on Ebay!

      15.10 @ 90.42mph
      The quest for 9s ceased, now the goal is a circuit track monster!
      Current fastest Laguna Seca Lap: 1:52.889

      Comment


        #18
        More usually it's the rpm increase that cause the bigger problem, but the cam grind can also affect valve bounce (with faster / higher lift), so even if the rpm are not raised it's possible that stiffer springs might be needed with a cam change. I'd pay more attention to what the cam maker says than to me...
        Regards from Oz,
        John.

        Comment


          #19
          Originally posted by af_1132 View Post
          When the shop owner was showing me how he thought I should lash the valves (he spoke with certainty), the cam rotated with only some resistance, an amount that didn't alarm him or me at all. Even at home, when the screws in the rocker arms and the lock nuts are all loose, the cam rotates with that same amount of manageable resistance.
          With no spring resistance (i.e. no valve opening occurring) there should be zero resistance to rotating the camshaft. If there is then you need to ascertain what's causing it.

          Originally posted by af_1132 View Post
          After I started going through the sequence and setting clearances, then it became progressively harder to rotate the cam.
          Which is normal.

          Originally posted by af_1132 View Post
          Furthermore, only when starting at TDC, rotating 270 degrees clockwise, and setting clearances in the firing order (1-3-4-2), did it become too hard to rotate with my ratchet, and this happened precisely after setting cylinder 4 and moving to cylinder 2. I got it to rotate through 180 degrees, so it was at TDC, and that is where it would not go further, except to twist and snap the bolt in 2 pieces.
          Which isn't normal.

          Originally posted by af_1132 View Post
          "Snap' is really the wrong word for what happened. I noticed the cam wasn't turning, but my ratchet was. I quickly took the bolt out entirely to see if it was okay. Most threads looked normal, but about four rows of threads near the head were quite spread out. My next thought was idiocy, "Well, I guess it's a special bolt with two levels of threads". I put it back in, tried to rotate again and that's when it split into two.
          No such thing as a "two level" thread.

          Originally posted by af_1132 View Post
          When ordering the cam with Janet on the phone, I decided to have her order a new cam from Honda instead of send mine as a core. I hope this isn't a, what I will call, "wagon r" cam. I'm starting to get worried, though.
          I'd be carefully checking that no springs are becoming coil bound near full lift. With a large increase in lift it's conceivable that this could occur, if so then it would require the spring seats on the head to be machined lower.
          Regards from Oz,
          John.

          Comment


            #20
            Here we go: http://www.cb7tuner.com/vbb/showthread.php?t=43270

            I will check for a coil bound condition on the springs when I do this properly. After reading the above thread, I believe that I was applying too much torque to the lock nuts after adjustments. That may have been part of the problem, perhaps.
            *** Think of others before thinking of yourself. ***
            ********** Spread love, not hate. ***********
            ****Lift others up with kind and helpful words****

            F20A_CB7, I miss you, but I will see you one day.
            "Nothing a little prayer can't fix."


            MRT
            Selling on Ebay!

            15.10 @ 90.42mph
            The quest for 9s ceased, now the goal is a circuit track monster!
            Current fastest Laguna Seca Lap: 1:52.889

            Comment


              #21
              Originally posted by af_1132 View Post
              After reading the above thread, I believe that I was applying too much torque to the lock nuts after adjustments. That may have been part of the problem, perhaps.
              No, that will only affect how tight the lock nuts are, which might cause some swearing the next time you try to loosen them.

              Some semi random thoughts:

              Checking for coil bind, if the spring set uses dual coils (one smaller spring inside a larger outer spring), don't forget to check the inner springs as well.

              Even if the coils don't actually become bound when the camshaft is rotated, there should be some significant clearance between coils at full lift. If not (i.e. coil to coil clearance exists but is too small) then higher rpm coil oscillations may possibly cause individual coils to impact other individual coils at certain harmonic frequencies, which (I've read) could conceivably lead to spring failure (this is what dual coil springs sets are designed to combat, i.e. the friction of one spring contacting the other spring dampens the harmonic oscillation of the other spring, but this can only do so much). I'd ask the camshaft or spring manufacturer, or a good engine builder how much clearance is needed between coils at full lift.

              Of course all the springs should have the same free length (i.e. from valve to valve, the inner and the outer spring in a set of two may intentionally have differing lengths), but ideally also the same compressed length at both no lift and full lift. There's no point having some springs more compressed at X lift than any other springs (comparing like to like, i.e. inlets to inlets and exhausts to exhausts).

              The rpm is limited by the point at which any individual valve starts to 'bounce', having any other spring more strongly compressed only increases the force needed to open its valve. Exhaust valve springs may be less stiff than inlet valve springs because the inlets are larger and heavier, so require a stronger spring to control valve mass (i.e. to control valve bounce).

              Coil binding (or inadequate gaps between coils) can be addressed by machining the spring seats on the head. Compressed length can be adjusted by shimming under the base of the springs. The spring or cam manufacturer should be able to tell you how compressed the springs should be at installed static height, which should be good enough to ensure that the full lift length is near enough. If installed spring length is too long (i.e. doesn't require enough compressing to install), then at full lift the spring may not exert it's intended force on the valve.

              This degree of attention to detail re equality of compressed length valve to valve may be overkill for a road engine, but not for a serious high rpm race motor.
              Regards from Oz,
              John.

              Comment


                #22
                When I get the head on and the timing belt installed, I will check for coil binding. I'm doing a few other things right now, so I did some research in the mean time on seat pressure for these Bisi Pro Springs and proper cam lubrication.

                Seat Pressure: Incredibly high! Bisi measured 76lbs seated and 195lbs at .500" lift! Wed3k measured on his own set and got 90lbs seated! That is about double the stock seat pressure, according to Wed3k's stock 45lbs measurements. I'm pretty sure that is at least part of the problem of a hard to turn cam on the bench. With a 7k rev limiter on my basemap, I am going to lose low end power with these .

                Lube: Web cams says to use their lube and that's it, but that stuff is high viscosity and sticky now (it's been in my room on my desk, not outside), so I'm wondering if more additives are needed before a first startup. Erik recently recommended Lucas Oil Stabilizer as a lube for both lobes and journals. Every cam company out there has a different recommendation, but I know there are reasons for that. I'm going to put Lucas on there before the cam is turned again. Hopefully, that will help.
                *** Think of others before thinking of yourself. ***
                ********** Spread love, not hate. ***********
                ****Lift others up with kind and helpful words****

                F20A_CB7, I miss you, but I will see you one day.
                "Nothing a little prayer can't fix."


                MRT
                Selling on Ebay!

                15.10 @ 90.42mph
                The quest for 9s ceased, now the goal is a circuit track monster!
                Current fastest Laguna Seca Lap: 1:52.889

                Comment


                  #23
                  i had some Skunk2 springs with a crazy high pressure (in my H) and they caused extreme wear between the rockers and the cam. Some say it was related to the metals used, but looking back now, I cant imagine how such extreme pressure wouldnt cause problems with the lubricated surfaces, even if the metals were properly compatible. Good thing you checked those while it was still on the bench, personally I would feel very iffy about running them that stiff.


                  - 1993 Accord LX - White sedan (sold)
                  - 1993 Accord EX - White sedan (wrecked)
                  - 1991 Accord EX - White sedan (sold)
                  - 1990 Accord EX - Grey sedan (sold)
                  - 1993 Accord EX - White sedan (sold)
                  - 1992 Accord EX - White coupe (sold)
                  - 1993 Accord EX - Grey coupe (stolen)
                  - 1993 Accord SE - Gold coupe (sold)
                  Current cars:
                  - 2005 Subaru Legacy GT Wagon - Daily driver
                  - 2004 Chevrolet Express AWD - Camper conversion

                  Comment


                    #24
                    cp[mike], do you still have the pressure readings for those stkunk2 springs seated and at full lift? I know it's a different engine, but I'm wondering how much stronger your Skunk2 springs were than stock.

                    Originally posted by johnl View Post
                    Are you intending to rev the engine to significantly higher rpm than the stock redline? If yes then you may need stiffer valve springs, if not then stiffer springs can do more harm than good. I can rev my stock 370,000km old engine to the rev limiter with no obvious sign of the valves 'bouncing', and preventing valve bounce is the only good reason to fit stiffer springs.
                    I had the basemap set at a 7k rev limit, so not significantly higher than stock, but higher than stock. So, based on what these springs are made for, do I really need them (conservative driving to the track, drag racing to 7k, then driving home)? I guess they will be doing more harm than good based on what you guys have said.

                    uuuuugh ! What are the N/A stage 2 cam guys supposed to do? The only options we have are stock springs or Bisi Springs for the F series, as far as I know.

                    jdm92_accorn ran the Bisi springs and level 2 regrind with OEM retainers and keepers when he had his F22A head, like my head, albeit much else was different between our bulids. I'm going to have to ask him about his experience and if he discovered wear between rockers and cam when he took it apart.

                    I have another idea. There are two different types of OEM springs on Majestic Honda: one set for intake and another set for exhaust. When you order Bisi springs, they come in a set of 16 and they look identical. When you open up the packaging, they are in two sets of 8 each, but are not labeled as intake or exhaust. This lead me to think that the Bisi springs are all the same, and so I sent them to the machine shop as 16 identical springs. If they are actually not all identical, then I'm sure some intake springs are on the exhaust side and vice versa.

                    Thanks, everyone, for helping me get to the bottom of this.
                    *** Think of others before thinking of yourself. ***
                    ********** Spread love, not hate. ***********
                    ****Lift others up with kind and helpful words****

                    F20A_CB7, I miss you, but I will see you one day.
                    "Nothing a little prayer can't fix."


                    MRT
                    Selling on Ebay!

                    15.10 @ 90.42mph
                    The quest for 9s ceased, now the goal is a circuit track monster!
                    Current fastest Laguna Seca Lap: 1:52.889

                    Comment


                      #25
                      I don't know what spring pressures are going to be required with the cam you intend to use, and I'm no expert on this, but those numbers seem extraordinarily high to me. I'd be asking the camshaft manufacturer.

                      The springs themselves don't take much extra power to run, because what the spring takes away as the cam rotates it then gives back (minus that part of the energy imparted into the spring that manifests as internal spring metal heating, which I understand to be a quite minor &#37. Turning the cam by hand what you'll probably find is that the cam is harder to rotate as a lobe is opening a valve, then harder to prevent the valve 'snapping' shut as the lobe goes over centre.

                      The stronger the spring though, the greater the frictional loss (heat) at the cam lobe and follower faces. Cam and follower faces are the most highly loaded surfaces in any 4 stroke engine, even with moderate spring stiffness. Cam wear? Not hugely surprised...
                      Last edited by johnl; 12-13-2014, 12:32 AM.
                      Regards from Oz,
                      John.

                      Comment


                        #26
                        Just did the valve clearance adjustments with the head on the car and the timing done. Man, that was so much easier, minus the fact that I had straight feeler gauges. I will document how things are going when I start the car.
                        *** Think of others before thinking of yourself. ***
                        ********** Spread love, not hate. ***********
                        ****Lift others up with kind and helpful words****

                        F20A_CB7, I miss you, but I will see you one day.
                        "Nothing a little prayer can't fix."


                        MRT
                        Selling on Ebay!

                        15.10 @ 90.42mph
                        The quest for 9s ceased, now the goal is a circuit track monster!
                        Current fastest Laguna Seca Lap: 1:52.889

                        Comment

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