Engine Rebuild question about rocker arms and push rods

Discussion in 'Engine, Fuel and Exhaust' started by sincityharley, Apr 3, 2011.

  1. sincityharley

    sincityharley Member

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    I'm doing a top end rebuild on a 2002 Heritage Softail EFI. I was following the manual line by line. During the rebuild while installing the rocker assembly I followed the directions to find TDC by rotating the wheel while we had a finger on the spark plug hole. We stopped rotating as soon as the air flow through the hole stopped right before it started sucking in. As we started installing the rocker assembly it didn't lay completely flat. We had to ratchet down the rocker assembly and we could feel tension as the rocker assembly was becoming flush. The manual stated that the push rods should spin freely. They weren't able to spin at all. After we torqued it down and rotated the wheel a full revolution back to TDC the push rods would spin freely. Obviously we ran the risk of potentially bending the push rods. The fact that we were able to rotate the tire and get everything at rest to where we could spin the rods, I'm wondering where I went wrong. The piston was most definitely at TDC. We were able to shine a light through the spark plug hole and verify. Ive finished the first cylinder and will be starting on the second in the coming week. Id like to have the second one come together correctly. Any advice would be greatly appreciated.
     
  2. BOBFLHTC

    BOBFLHTC Active Member

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    Last year I did a Top End rebuild on my EVO but I had problems with the Middle Rocker cover shifting and leaking so I decided to install a two piece Rocker cover. Last summer I turned the rear wheel looking for TDC for the Push rod adjustment. This time I decided to try a different approach. After thinking about it I wanted to adjust the Push rod when the Lifter is at the lowest point sitting on the flat portion of the cam with the valve closed.

    So I removed the Push rods and took 4 fender washers and used metal tape to secure them to the top of the lifter blocks. I then placed a 3 inch bolt in each one and marked the bolt with a felt tip when it was at the lowest point. I then proceeded to turn the motor over and inserted and adjusted the push rod for whatever lifter was at the lowest point. The rising and falling bolts give a visual for the lifter position.

    It’s been chilly here in New Jersey but I’ve been out riding several times and it runs great. I saved the bolts and washers for future reference. I just wanted a way to do it that I could feel confident about the cam being in the right position. Best of luck with it - Bob
     
  3. BUBBIE

    BUBBIE Well-Known Member

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    I have to agree with T.,,,, the Fact is "the lifter needed TIME to "Bleed Off"..

    IF you had High Lift cams in that motor You Might of had a problem Bending a Valve.. I think the KEY here is;
    Get Up Go Have A Coffee and WAIT until you Can turn the push rod easily... It does take time... Don''t hurry this part of the operation Dr.:newsmile105:

    signed....BUBBIE
     
  4. flyingdutchman

    flyingdutchman New Member

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    I've done this several times (once again just yesterday, in fact!), I'll try to explain, hope that I'm right. The real mechanics will correct me, if I'm wrong. The manual is right, if you read it slowly, and a few times.
    The piston needs to be at TDC on a compression stroke. Both lifters will be at the bottom of their travel, and both valves closed. If it's at TDC of the exhaust stroke, one or the other of the valves is open. If you have the piston at TDC of the compression stroke, then when you install the rockers, you will be compressing the lifter internal pistons about .100" of their travel. My method, if you don't have the pushrod tubes off, is to have the pushrods sitting on the lifters. When you spin the motor one rod or the other will be moving up or down. When you see both rods at their lowest point, you can spin the motor slightly back and forth, and neither rod will move. Since the lifter is made to compress very slowly, what is actually happening is that you are opening both intake and exhaust valves slightly when you torque down the rocker arm support plate. There is a note in the service manual (mine anyway) about threading the bolts in til the bolt heads contact the support plate, then tightening each bolt 1/4 turn at a time, to prevent warpage. Then, after torquing is complete, you wait 10 minutes or more for the valve springs to make the lifters bleed down, at which point you'll be able to spin the pushrods. If you turn the motor before then, it's possible for the valves to crash on the pistons.
    Hope this helps.
     
  5. Jack Klarich

    Jack Klarich Expert Member

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    That is a very good write up that all can understand Thanks for posting it