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Thread: New head, gotta use new rocker arm bearings?

  1. #1

    Array
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    Join Date
    03-11-2024
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    3
    Location

    Pearl, Illinois
    Vehicle

    1990 Mitsubishi Mighty Max
    Engine

    4G64

    New head, gotta use new rocker arm bearings?

    I just bought a new 8 valve SOHC head for my 1990 mighty max, 4g64. I switched all the valves and rocker arms and everything over to the new head, but used the old rocker arm 'bearings?" I am confused if they are bearings because as far as I know, there WERE no cam bearings in the engine. Well, when the rocker arm assembly bolts are loose it snaps right over to the next valve, sharp and CWISP, but then when I tighten them down to even just 10 foot pound, it binds and locks up tight as a drum. Loosen them back up, snaps right back over. I'm going to mess with it again tomorrow, but I am confused and so is my father and others in my life.

    Me and my father did have the thought a minute ago that maybe because we used the old cam and rocker arm assembly and all that when I tighten it down it binds with the new bottom bearings in the head, and are gonna try switching them all over to the new rocker arm 'bearings' and caps that came with the new head, in case the difference in wear with a used cam and a new head causes it to bind when tightened down?

    Any advice would be greatly appreciated.

  2. #2

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    07-23-2018
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    448
    Location

    Seattle, WA
    Vehicle

    1988 Dodge Power Ram 50
    Engine

    G54B
    Your suspicion that using the old cam bearing caps on the new head is causing the binding is correct. Use the new cam caps which are mated to the new head. That should resolve the problem. Be sure to install the waved washers, springs, bearing caps and rockers onto the rocker arm shafts in the original order to ensure correct rocker-to-valve stem contact.

    By the way, welcome to MR50.

  3. #3

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    03-11-2024
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    Location

    Pearl, Illinois
    Vehicle

    1990 Mitsubishi Mighty Max
    Engine

    4G64
    Thank you so much, I was worried that was the way it was. I didn't want to have to totally tear down that rack assembly and all those bits and pieces, but I'll take it as a chance to clean them all and lubricate them well.

  4. #4

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    07-23-2018
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    Location

    Seattle, WA
    Vehicle

    1988 Dodge Power Ram 50
    Engine

    G54B
    Here are pages from the service manual that should help:

    Attached Images

  5. #5

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    03-11-2024
    Posts
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    Location

    Pearl, Illinois
    Vehicle

    1990 Mitsubishi Mighty Max
    Engine

    4G64
    Thank you! I got it all put together and it's whipping over just fine now. Got it all put together and gotta get a battery now to hope I got it in time.

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