Valve train tapping?

Discussion in 'Engine, Fuel and Exhaust' started by TQuentin1, Mar 18, 2009.

  1. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    OK, folks. As you may know, last week I redid my cam chest with the roller chain conversion installing the Andrews Products N21 cams, adjustable pushrods and the TFI fueler. I am impressed with the added pep the bike has, and will see if I need to fiddle with the settings on the TFI based on fuel mileage and the condition of the plugs.

    Since doing the project, I am super sensitive to every little noise the engine is making. I started hearing a noise that seemed like pretty bad valve tapping. By accident I found that the front fender running light amber cover was rattling around. I have dampened that out with some loop-side velcro under the edges of the lens. Done.

    But there is a valve noise that I can hear. It is more noticeable when accelerating, and I can hear it faintly at constant speed (rpm). If I let up on the throttle and let the bike slow against engine load, there is no discernible valve tap. This may have been the case before I did the up-grade, but I was not sensitized to it or even listening for it over the radio. There just may be more slop in the upper end of the valve train due to wear.

    So the question is: should I try to adjust this out with the pushrods? I have this nagging thought that I read somewhere that adjusting for valve-train tapping with adjustable pushrods is counter intuitive and that you DO NOT lengthen the pushrods, but rather adjust them shorter. But this does not make sense to me, so it may be something I am mis-remembering, right?

    If I am going to adjust the pushrods, do I collapse the pushrods, let the lifters recover and start over on the adjustment process adding a flat to the adjustment spec (three full turns in my case)? Or should I just readjust to spec and see if I had adjusted them wrong the first time around (don't think so)?

    Let me know what you folks suggest.

    TQ
     
  2. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    TQ, are your tappets solid or hydralic? If adjusting hydralic tappets, the pushrods are adjusted till there is zero lash and then extended 1 turn or so, to "preload" lifters slightly. This assures there is zero lash during normal operation, so even at high speed (max RPM) you do not experience "hydralic pump up" (which could float the valves open). At least that was from my old automotive experience with performance hydralic "anti-pump-up" roller/tappet lifters.
     
  3. glider

    glider Veteran Member

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    TQ

    I'm sure you let the tappets bleed down sufficiently before moving on to adjust the next one when adjusting the pushrods after reassembly. Also check the pushrod covers when using the adjustable pushrods, they have a way of rubbing on the covers and giving you a noise that can be mistaken for a valve tap.
     
  4. kemo

    kemo R.I.P

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    TQ I am going to adjust my p/r's when I get back home to Canada in 3 weeks. I will back all push rods off and let them bleed off and then just go back to them later and set them at 0 lash and tighten them 3 turns. I have put 7000 miles on them down here and been listening to some tapping but everthing is ok, so don't get to panicky about them unless they are really bothering you.
     
  5. glider

    glider Veteran Member

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    It's important kemo to let the adjusted one that you just did bleed down before rotating the engine into position to do the next one.
     
  6. kemo

    kemo R.I.P

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    Thanks Glider, I figure by the time I get the clip back into the p/r tube that should be about enough time for the lifter be bled down. I am not too quick getting that clip in, seems that I have too many awkward hands. Anybody use anything different then a screw driver to install the clip. I have thought about a putty knife or a spoon or something.
     
  7. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Yeah, like Kemo says below, by the time I get the pushrods cover clips back on (wish I had bought THAT tool!!) and finish fooling around doing stuff, it has probably been 30 min. or more from adjusting the last one. Will put my long screw driver on the covers to see if that might be the tapping like problem.

    Right. Sounds like we both have the same instructions for our pushrods. Mine are also 3 full turns from zero lash.

    So when adjusting pushrods that are still in the bike (not new), how long does it take the lifter to fully expand when you collapse the pushrod? Is it immediate, or do you have to give them some time for the spring to fully extend them?
     
  8. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    They are hydraulic. In fact the HD "B" lifter. Instructions with the pushrods call for 3 full turns from zero lash. I was very AR in doing this slowly and carefully so that I was sure that I turned everything correctly.

    TQ
     
  9. mopar

    mopar Member

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    TQ, I am in the same position as you with valve noise. i think I am over reacting. I had adjustable PR installed. They were noisey. Pulled them out. replaced them with perfect fit PR. A lot quieter but gets noisier when hot. I purchased tapered adjustable PR. haven't installed them yet. I purchased a stethescope to pinpoint where the noise was comming from and everything sounds good. Sounds worse when standing by the bike than throught the scope. Through the scope, the primary chain sounds much worse than any of the valve train.
     
  10. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Mopar and Kemo,

    I talked to John Wadsworth (Herko) today about the tapping. He said in his experience it is not unusual for guys to under adjust their pushrods. John does not use the "number of turns" method to adjust pushrods, but rather uses a gauge going for .140" out from zero lash. He said that is a bit over half the total travel of the lifter barrel. Using the info that Glider has here:

    Adjusting Pushrods - Harley Davidson Community

    for a 24tpi pushrod, .140"/.0417 = 3.35 turns or about 3 turns and 2 flats (which is actually .1389" out). I will think about this and see if I will split the difference and start with 3 turns and 1 flat (which would be .132" out) and see how that does, or just go for it!!

    He also suggested making sure that the lifter covers are centered to reduce any noise associated with the pushrods rubbing against the pushrod covers like Glider suggested above. I will use the alignment screws I got for the oil pump to do this like we have to do to align the lifter blocks on EVOs.

    Finally, John said that about 20% of the new adjustable pushrod set he sees have manufacturing debris INSIDE the tubes or adjusting ends!! He suggests taking the pushrods out, dissassembling each and cleaning them out with brake cleaner spray or carburetor spray.

    So that is this weekend!!

    TQ