Adjustable push rod question for those who have done this more than I have.

Discussion in 'Engine, Fuel and Exhaust' started by SoonerSoftail, Nov 26, 2010.

  1. SoonerSoftail

    SoonerSoftail Active Member

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    Since upgrading my cams/cam drive it seems the top end is a bit more noisy. In the post of TQ's it calculates that SE push rods with 32TPI would be 3 to 4turns to get the .100 inch of "crush" that HD "B" lifters need, not the 2 1/2 turns the instructions call for. Could it be that Harley is a little conservative on the length adjustment for some reason?
     
  2. Hoople

    Hoople Account Removed

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    Have you changed brands or grades of oil since the cam swap. Did you change the oil after the cam swap and is your oil pressure the same as it was (pump alignment) since the cam swap.

    Oil pressure and flow could change from a different pump alignment. I would gauge it just to be sure.
     
  3. kemo

    kemo R.I.P

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    I have S/E adj push rods. I use 4 turns, no problems. A caution on the jam nuts, they are known to crack and split, so easy on the torque.
    kemo
     
  4. SoonerSoftail

    SoonerSoftail Active Member

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    Same oil. Haven't guaged it but based on the fact that the oil pressure light used to take a second or two to go off before at start up and now goes off immediately I would say oil pressure is better.



    I'm thinking this is the problem. 2 1/2 turns from zero lash just isn't enough. I tossed the stock nuts and am using some from the bins here at work. They're about .100 taller than the stock nuts. Also grade 8. They should be tougher.
     
  5. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    The total travel on the "B" lifters is a quarter inch. So you want to adjust your pushrods to at least half that travel or .125". If your pushrods are 32 tpi, then:

    32 x 0.125 = 4 full turns for the half lifter piston travel.

    I personally like to adjust the pushrods out (longer) a bit more than half the travel. My pushrods (V Thunder - V Thunder: Pushrods) are 24 tpi. So I adjust the full 3 turns plus 2 flats. So that is:

    1/24 x 3.33 = 0.139" out from zero lash.

    If you went an additional 2 flats from 4 full turns it would be:

    1/32 x 4.33 = 0.135" out from zero lash.

    Your call, of course.

    TQ
     
  6. R.Bingham

    R.Bingham Active Member

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    When I changed cams the Indy who replaced the inner cam bearings for me said to do 3 full turns on the SE tapered quick install push rods. Yes the instructions say 2 1/2 turns but he told me he always sets his at 3 turns. He does this everyday for a living so I took his word and haven't had any problems.

    Randall
     
  7. Jack Klarich

    Jack Klarich Expert Member

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    It would be a bit noisey if too loose, and error on the loose side so not to hang a valve would be my guess, I like to set them so I can just spin the push rod, unless you are using say S S lifters that act like solids @ high RPM
     
  8. SoonerSoftail

    SoonerSoftail Active Member

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    I'm going to readjust to 3 turns and see if it quiets down. My guess is that it will. I've built a few SB Chevy racing motors with adjustable rocker arms and 1/2 to 3/4 turn on them can make a lot of difference. That's got to be the same on a HD motor. Old age I guess but I have seem to have a little trouble transferring everything I learned building car engines to a Twin Cam. Also, I wanted to double check this afternoon before I said anything but SE tapered rods are 24 TPI not 32 TPI as all the charts I've seen say. 24 TPI would still call for 3 turns past zero lash.
     
  9. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Check the packaging or instructions that came with them (if you still have it). I don't have any specific info on those, and can't find any quickly on the NET.

    Worse case, if you can't find any reliable info on what tpi they are, then when you go to adjust them again, take one out and just measure the number of threads in an inch on the threaded tube. Set your caliper to EXACTLY one inch, hold it against the threaded tube, and count the threads. It will be obvious if it is 24, 28 or 32 threads. If you don't have calipers (and for some reason don't want to go get some?) use a steel machinist ruler. You will be close enough to tell the difference!!

    TQ
     
  10. SoonerSoftail

    SoonerSoftail Active Member

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    I know they're 24. I went back and checked the bin that I got the nuts from to replace the stock ones. Then just to make sure I hadn't lost my mind I checked the nuts on a 24TPI bolt. Funny thing how many places I've seen on various forums that say the 18404-08 tapered rods are 32 when they're not, they are most definately 24.