How many turns?

Discussion in 'GM Powertrain' started by kcfocus1, Sep 3, 2010.

  1. kcfocus1

    kcfocus1 New Member

    I have a 1990 305 silverado with 360,000 on it. I have really tall gears and 700r4.
    Engine is dying gracefully but had to free up a lifter. Now my question to persons
    with experience is how many turns past 0 lash on a healthy geriatrics motor?
    I have heard everything from 1/2 all the way to a healthy full turn!
    I would like to complete this as soon as I receive a response.... Hate walking Thanks
  2. Chris Miller

    Chris Miller Rockstar 100 Posts

    I usually go 1/2 for higher-performance apps, or 3/4 for everyday driving.
    Since you've got 360K miles, go with a 3/4 turn.
  3. daddytech

    daddytech Epic Member 5+ Years 500 Posts

    never really had one "THAT" tired lol closest i have gotten is the 269,000 that's on my 1989 silverado and i just reset all of those to zero lash and it's fine.
  4. lildino383

    lildino383 New Member

    Wow...some go further than necessary. You require .030" lash setting assuming you are using hydraulic lifters. That equates to 1/4 to 1/2 turn. Any more causes valves to float; any less will create valvetrain noise. This is your basic rule of thumb. If you are having problems, though, you shouldn't hesitate to replace the lifters. And make certain that you add ZDDP to the oil. Flat tappets are unfortunate victims of today's oil. If it's a performance cam, you should also remove the inner valve spring for breaking-in the lifters. If it's stock, you should be alright. Best of luck!
  5. Chris Miller

    Chris Miller Rockstar 100 Posts

    lildino, zero lash isn't achieved when you turn it until the ticking stops. It's achieved somewhat after that. The factory setting on that 350 is more like a full turn, but I usually recommend a 3/4 turn if the engine has a lot of miles. Plus, it cuts down on wear substantially.
  6. lildino383

    lildino383 New Member

    I'm assuming you are setting the lifters while engine is running? Messy. Overloading the lifters actually causes premature wear of the internals. If you have to overtighten them, they are worn....replace them and use additives to prevent future losses.
    I only strongly defend this statement due to the fact that we aren't allowed to post the findings from the met lab. All I am permitted to say is that overtightening the lifters (however miniscule) does cause the internals to expire quicker than adequate torque. This amount doesn't immediately show, but will shorten the lifespan.
    Granted, you should still see a good couple thousand hours of use from any good quality lifter. But, we have seen quite a few only live half the life due to excessive pressure. Spending this much time analyzing metalurgical stresses can sometimes make you a bit paranoid about what goes on inside your engine.
    Sorry about the lengthy commentary.
    Last edited: Sep 8, 2010

    DAREDEVIL Rockstar 4 Years 1000 Posts

    i am 100% with u !!!!

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