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valve adjustment

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by ftn96, Oct 13, 2000.

  1. ftn96

    ftn96 1/2 ton status

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    Can anyone refresh my memory on adjusting the valves on the a 350. Think it is the same proceedure on all GM motors. Think you can do it while engine is running, tighten them down till they stop clattering then back off 1/2 turn or something to that effect.

    Don't you buy no ugly truck!
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I beleive its tighten until they stop clattering and then a half a turn more. I'm sure someone has the exact procedure. [​IMG]

    Rene

    [​IMG]
     
  3. ken

    ken 1/2 ton status

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    Back off till clattering, then tighten till just no clattering, then I go 1/4 of a turn more, but the manual will tell you more. When I am building a new engine, I tighten the rockers in this way (tighten till all up and down slack is removed), then go 1/4-1/3 turn tighter. I fire the engine up and never have to adjust while running!!!

    ken
     
  4. ftn96

    ftn96 1/2 ton status

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    Well, I've only had this jimmy about 2 months and I had to lay it to the floor the other day adn the damn valves stated to dance the the nashville symphony. May be cheap gas but, I don't think it would hurt to get in there and make sure. Whatch' y'all think?

    Don't you buy no ugly truck!
     
  5. Wheels

    Wheels 1/2 ton status

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    Valve chattering would be noticeable at idle. When you romped on it and it made that sound it's from pre-ignition (pinging). Once you adjust the valves on a chevy you shouldn't have to adjust them again. If you do then the cam lobes are getting flattened or a stud is starting to pull out. Check timing and if it's not chattering at idle, then adjust your timing to get the oinging out.
     
  6. ftn96

    ftn96 1/2 ton status

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    Well don't I feel like a dumba**. Thanks man. I knew that but its just been so long since I've tinkered with cars. All that knowledge has slipped off to the back of my brain somewhere.

    Don't you buy no ugly truck!
     
  7. bart

    bart Registered Member

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    on a newly installed valvetrain, back off the adjusting nut on the rocker all the way, position the cylinder at TDC (both valves closed), while spinning the pushrod between two fingers, tighten down the nut until you feel resistance on the pushrod, then tighten 1 turn +/- 1/4 turn..so that's 3/4 to 1 and 1/4 turns tight. Do this only once..if you have collapsed a lifter, you will need to let it return in order to not hold valves open which is most noticeable by a backfire or a miss and noise in the exhaust.

    Bart
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Would that be a miss under load? Backfire, not immediatly but say when lugging (4 speed)? Just curious (yeah right[​IMG])

    Rene

    [​IMG]
     
  9. bart

    bart Registered Member

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    that would be a miss all the time if the valve doesn't close all the way..even just a tiny bit the cylinder will never draw a vacuum and thus never take in an air/fuel charge..

    bart
     

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