adjusting valves twin cam 88

Discussion in 'Engine, Fuel and Exhaust' started by Fearless1, Oct 18, 2008.

  1. Fearless1

    Fearless1 Active Member

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    I had cam bearings go out now putting motor back together and need to adjust the valves they are oversized cams with adjustable pushrods. My old sporty was to get the front cylnder on compression stroke top dead center then adjust the front 2 pushrods to just a tad of slop then do the same to the back is the twin cam 88 adjusted the same? The twin cam has hydraulic lifters and the old sporty was solid lifters.
     
  2. papaseven

    papaseven Member

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    It depends on the pushrod because different brands have a different thread pitch. Yours should have come with an instruction sheet.
    At TDC on the compression stroke adjust each pushrod on that cylinder until you just barely remove all slack. Then turn each pushrod out the prescribed number of turns to preload the lifter and tighten the locknut.
    IMPORTANT!! Now let everthing sit for 15 minutes to allow the lifters to bleed down before you roll the motor over for the other cylinder. You should be able to turn the pushrod with your fingertips. Don't skip this step or you can add replacing a valve or two to your list.
    Now slowly roll the motor to TDC of the other cylinder and repeat.

    Your trying to achieve .100 lifter preload so if you know the thread pitch it's easy.
    20tpi will require 2 turns, 32 will require 3.2 turns, 40 will need 4 turns and so on.

    Most guys set them at two turns and call it good.

    Personally I like to preload the lifter about .075 and it keeps the lifter noise at high speeds down to a minimum.

    Hope this helps.
    Geno
     
  3. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    When you did the cams and pushrods, did you have a set of instructions? That should have given you the procedures. If not, do you know what they were. Typically you can find the procedures on-line somewhere knowing what the cams and pushrods were.

    TQ
     
  4. Fearless1

    Fearless1 Active Member

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    Crane pushrods with screaming eagle 205 cams I believe (that is what is stamped on them) with no instructions. i can't seem to get the valves correct it runs but not well, I thought I might have got the cams 1 tooth off maybe so I tore it down again and everything looks fine. Got to get it going today to drive to work so any help here would be highly appreciated.
     
  5. glider

    glider Veteran Member

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    The search feature works real well on the forum.:s

    Adjusting Pushrods - Harley Davidson Community
     
  6. Fearless1

    Fearless1 Active Member

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    Ok I read the post and tried it like it said but the only way I can get it to run right is just snug so you can still turn them with your fingers. If I go past that point it dosen't run right. Now my next problem is the top end seems to be running hot any ideas why?
     
  7. glider

    glider Veteran Member

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    Maybe a compression test would show something here. If the valves are out of adjustment, it would tend to heat things up a bit.
     
  8. papaseven

    papaseven Member

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    The Crane pushrods should be set at three turns from zero lash.

    The trick is to get the cylinder at TDC on the compression stoke and then turn the pushrod out until you just barely remove any slack then an additional three turns out.

    If you lengthen the pushrod until you can barely turn it and then add the preload you're going to far. The lifter spring isn't very strong so you have to use a deft feel when you adjust them to zero lash.

    If it's holding an exhaust valve slightly off the seat it may still run but will overheat pronto and can burn a valve.

    IMPORTANT!!!!
    If the cam chest had debris from the old bearings then you will have to replace the lifters. The debris will block the bleed holes and cause the lifter to pump up and hold the valves off the seat regardless of the setting.

    The oil pump is probably trashed too. The debris can also block the oil pump relief valve and cause it to have too much oil pressure ( which will pump up the lifters ) or no oil pressure.

    If the bearings actually trashed themselves then the wise thing to do is split the cases and clean and inspect every part for damage. You should also clean all fittings, lines and oil tank or pan.
    It only takes one tiny piece to turn that TC into a 4000.00 boat anchor.:(

    Good Luck
    Geno
     
  9. Fearless1

    Fearless1 Active Member

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    I removed the oil sending unit and fired her up it only chugged out spurts of oil, how much pressure is there spose to be out of it?
     
  10. gs34

    gs34 Junior Member

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    Fearless, That is some GOOD advice that Geno posted.
    If (in fact) you had debris in the engine from the bearing failure, and you do not do a complete clean out, your repairs could go south in a hurry.
    You've got to just bite the bullet and take the time to go completely thru it. The consequences of not getting every bit of debris out of ports, lines, and tanks could cost you the price of an engine.