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THE valve adjustment thread

Discussion in 'The Garage' started by 78Suburban, Apr 20, 2006.

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How do you adjust valves properly? Chose 2 Answers

  1. The motor has to be running

    8 vote(s)
    11.6%
  2. The motor has to at least be warmed up

    9 vote(s)
    13.0%
  3. The motor can be cold

    26 vote(s)
    37.7%
  4. 1/4 turn past 0 lash

    13 vote(s)
    18.8%
  5. 1/2 turn past 0 lash

    26 vote(s)
    37.7%
  6. 3/4 turn past 0 lash

    11 vote(s)
    15.9%
  7. 1 turn past 0 lash

    7 vote(s)
    10.1%
  8. nekkid

    3 vote(s)
    4.3%
  9. very nekkid

    6 vote(s)
    8.7%
  10. very very nekkid

    13 vote(s)
    18.8%
Multiple votes are allowed.
  1. 78Suburban

    78Suburban 1/2 ton status

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    It seems that valve adjustment is a majorly controversial subject that no one agrees on. I've been told that you have to adjust them with the motor running, I've also been told that you can adjust them with the motor off, but it has to be warmed up, I've also been told that it doesn't matter, adjust them weeks after the truck was last run.
    I used the meathod where you only have to turn the motor over once, so you adjust a certain set of valves with #1 at TDC compression stroke, and another set of valves at #1 TDC exhaust stroke. I had a link for the website that had the order, but I lost it. I did all of my adjustments with the motor cold. I hadn't cranked the truck in a month. I fired it up, and it idles great and there are no clacking rockers. So should I just call it good?
    I am talking about Hydraulic lifters here. I really would like to get some heated, logical arguments going on about valve adjustment.
    thanks,
    James
     
  2. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    On a junk yard 350 I got one that had hot rod parts on it went ahead and turned off 3/4 turn. Was able to turn it 7k Rs in the mud before floating valves.
     
    Last edited: Apr 20, 2006
  3. BadBob

    BadBob 1/2 ton status

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    Mopar used a sticker under the hood with that order on some of the old solid lifter max wedges (pretty sure B/RBs have the same firing order as GM). Year One probably still has it if you want to stick it somewhere handy :wink1:

    I think stock specs say 1 turn past 0 cold. Most performance type places do somewhere between 1/4 and 3/4 past 0.
     
  4. danny7139

    danny7139 1/2 ton status

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    I do 3/4 past 0 lash, just because it always got me to the most silent rockers I could get. If they still sound alittle after that then adjust them just alittle bit when running. Chevies have the loudest rockers out of the rest of the motors IMO anyway.
     
  5. jk3078

    jk3078 1/2 ton status

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    My chiltons says one turn past 0 lash for the running way, in 1/4 turn incriments.
     
  6. lockedup72

    lockedup72 Registered Member

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    depends on the cam manufacture, and type of rocker/nut combo. there is .060 play in the lifter. quite a few variables. for most stock, i put 4 threads above the nut, gone as far as adding or removing thousandths.
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The method you choose cannot always be done that way. If you have a really nasty cam it can't be done that way because of the valve overlap. Valve overlap means that BOTH valves are open at the same time at TDC. These nasty cams need to be done differently than anything else. There really is no right way to adjust valves when it comes to hydaulic cams. The only thing that needs to happen is to make sure that there is some preload on the lifters, this happens at anything past zero lash. The most ideal would be 1/2 turn past zero lash which preloads the lifter to about half of its hydraulic movement. The tighter you go the less RPM it will achieve and the less you go the more RPM it will achieve.
     
  8. 4xcrazy

    4xcrazy 3/4 ton status

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    I do the running method, doesn't matter hot or cold, loosen them up till they clack, tighten them up till they get quiet, then 1/4 turn incriments until you can juuuust start to hear the engine "sound" change, then i would back it out just a hair.

    you can definately hear when you get a valve too tight.
     
  9. reptilianman

    reptilianman Registered Member

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    Call it good James,thats the way GM requires it to be done.
     
  10. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    my chiltons manual... and father (mechanic of 45+ years) said....
    1 turn... however.... the chiltons manual... tells you with #1 @ TDC which valves to do.... and you do it in 1/4 turn increments.... then when done you turn the motor over so I think #6 is TDC then do the rest......
     
  11. 78Suburban

    78Suburban 1/2 ton status

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    ha ha, there are so many opinions. I'm gonna finish my cup of coffee, bust out my $3 cork gaskets, go bolt the valve covers down, and take it on a test drive around the house :D If it purs like a kitten when I get on it, I'll call it good
     
  12. R77K10

    R77K10 Banned

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    well everyone has their own opinions but on stock hydraulic lifters it is zero plus one full turn- no matter what anyone says


    but each to their own.

    and i dont know why ppl are talking about mopars in here, and aftermarket stuff either

    just gonna confuse everything for the noobs even more


    some ppl are just wierd on this subject and a few others too


    good luck
     
  13. diesel4me

    diesel4me 1 ton status Premium Member

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    the bible says...

    To adjust chevy V8 valves,the specs are one turn after zero lash(when it just stops ticking while running,,or the pushrod gets to hard to spin in your fingers with the engine off)..

    You set the motor on TDC on # 1 piston..both valves closed..adjust both valves on the #1 cylinder,and also the intake valves on #2,#5,#7--and the exhaust valves on #3,#4,and #8....

    Turn crank one full revolution..until pointer is at zero again...this is the top dead center of #6 piston...make sure both #6 valves are closed..now you can adjust the intakes on #3,#4,#6,and #8...and the exhaust on #2,#5,#6,and #7..

    I do them this way with the motor off..no oil mess,no possibility of bent pushrods or bent valves from doing it with the motor running..just adjust the rockers with the motor set at the TDC points listed,and when the pushrods cant be spun between your fingers,go one full turn more,and do the rest of them..put the valve covers on,and enjoy!..

    Some hot cams cant be adjusted the "stock" way as already noted..but it works great on most grinds..saves the valvetrain from excessive slop when first starting,which I think causes 90% of cam lobe failure in new cams installations..by the time you get the valves adjusted with it running,its already started wiping a lobe...:doah:

    I've noticed many motors I adjusted valves on idled faster afterwards--so I had to re-set the idle speed!..more than one had a noticeable gain in low end power and acceleration too..probably because the valves opened all the way now,instead of barely opening..

    I've seen some books that say some engines used only 3/4 of a turn,or one and a half turns past zero lash..but one turn is the usual spec listed,and seems to work fine in most cases...:crazy:
     
  14. draggbody

    draggbody 1/2 ton status

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    buy vortech heads and run them down till they stop... non adjustable!!!! at least they are on my BB... if not on a small block, then swap in a BB w/ vortech heads and follow above instructions... problem solved...
     
  15. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    This will blow up his engine. Vortech has nothing to do with non-adjustable rockers. All SBC's are adjustable rockers and ALL BBC's are adjustable up through the end of the gen V then starting with the gen VI the rocker adjustment changed to a bolt down type.
     
  16. draggbody

    draggbody 1/2 ton status

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    well maybe no one caught my sarcasm... oh, well... i dont know much about the sb vortech heads, but i do have them on my BB... just run them down til they stop and they are perfect!!!
     
  17. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    !very Very Nekkid!
     
  18. bent72

    bent72 Desert Solitaire Premium Member GMOTM Winner

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    I'll Listen to Scott, he has seen more motors than I will ever own...

    nekkid it is
     
  19. POWERMAD

    POWERMAD 1/2 ton status

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    My hydraulic cam seems to run best with .030" pre load.
    But that is a Rhoads cam.

    On a rebuild I mark the balancer 1/6, 8/5, 4/7,2/3
    If it is just a cam swap I just bar it over till the companion cylinder is on the rock.
    If the exhaust is closing and the intake starts to open on #6 I adjust #1.
    Bar it over to the next position, 5 is on the rock, adjust 8 and so on.
    The trick is zero lash, roller rockers make it easy as ya don't have a lock nut to confuse the issue.

    I go 1/2 turn past zero with a regular cam & lifter set, put the covers on and drive away.
    Been workin for me for over 20 years. YMMV
     
  20. carpeonnel

    carpeonnel 1/2 ton status

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    I'm about the replace the stock rocker arms with some PRW roller rockers I got and I trying to research replacing them and had a couple questions. My Haynes manual said that once TDC was found for #1 piston to rotate in 90* increments to adjust the other valves and to refer to the "specifications". What are the specifications? Is that just the normal firing order 1-8-4-3-6-5-7-2? Or can you just do what diesel 4me suggested?

     

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