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SBC valve adjust question

Discussion in 'The Hokey Ass Message Board' started by buschandbusch, Jun 8, 2008.

  1. buschandbusch
    Joined: Jan 11, 2006
    Posts: 1,293

    buschandbusch
    Member
    from Reno, NV

    hello, I'm trying to figure out if anything is wrong with my motor- I'm finally around to tearing it down, installing a new cam and trying to get it back on the road ASAP. Adjusted valves according to my manual, at TDC, get zero lash then go one turn extra on a certain set of intakes and exhausts. All the ones on 1,3,5,7 I can still turn the pushrods on them after adjustment. BUT, I can't turn the pushrods on any of the 2,4,6,8 valves I adjust. Turn the motor over one revolution and adjust the ones it tells me, again I can spin any of the 1,3,5,7 valves after adjustment, but NOT any of the 2,4,6,8 valves. Compression readings are all very similar cyclinder to cyclinder prior to the swap, so I doubt one head is shorter. Is that just the way it's supposed to feel? It's a stupid GM crate 350, hope I'm doing it correctly. :confused:
    thanks for any help!
     
  2. john56h
    Joined: Jan 28, 2007
    Posts: 1,760

    john56h
    Member

    When I adjust valves I do each valve separately.

    Beginning with the first cylinder, crank the engine slowly until the exhaust valve just starts to open...then set the lash (or preload for hydraulic) on the INTAKE valve for the same cylinder. Then rotate the engine until the intake valve has opened and is almost closed again...then set the lash on the EXHAUST valve. Repeat for each cylinder and you should be good to go.

    Set lash according to cam specs. For hydraulics, tighten the adjusting nut until the pushrod can just be spun by hand...then put 1/2 to 1 full turn on it to set preload.
     
  3. chopolds
    Joined: Oct 22, 2001
    Posts: 6,208

    chopolds
    Member
    from howell, nj
    1. Kustom Painters

    Setting the valves on a fresh smallblock is kind of tricky. You have to develop a feel for it. AND there are certain things you need to know that manuals do not tell you!
    First, did you presoak the lifters in oil, pushing down on them every once in a while to get them full?
    Next, you "can" follow the factory map in adjusting the rockers, so you only turn the engine once.
    Now, the actual adjustment. Try to get it right the first time, as when you adjust them, you do push out some oil, which can give you a different feel the next time you try to do it.
    Slowly tighten the adjusting nut. Try not to push down on the nut with your socket, though, it throws off your adjutment. Twirl the pushrod with your finger and thumb while tightening the nut, until the pushrod tightens up. A lot of guys think the pushrod had to stop turning altogether to get Zero lash, but that's not true, it's a hydraulic lifter! You have to develop a light touch, or you'll overtighten it!
    Once you get to zero lash, tighten it up 1/4 to 1/2 turn. NOT a full turn, like the manual suggests. I've NEVER had an engine run right doing it that much.
    That should do it, you shouldn't have to readjust it again. But like I said, if you mess up and try to redo it, most likely the lash will be too tight. At that point it pays to just wait until the engine is running, and do a running adjustment, at least on the offending lifter.
    And just so you know....I used to rebuild Camaro engines (actually just replace heads) for Exxon Reasearch and Engineering for valve deposit studies. On those engines, there is so much crap that goes over the valve covers, it's almost impossible to do running valve adjustments, so I got REAL good at doing them cold.......did them for years.
     
  4. Lobucrod
    Joined: Mar 22, 2006
    Posts: 4,122

    Lobucrod
    Alliance Vendor
    from Texas

    When I adjust hydralic lifters I dont spin the push rods, I lift them and let them fall back down and keep tightening the nut until i cant lift them. Spinning it or pushing down on the pushrod or rocker arm will be misleading of the lifter is dry. The spring that holds the plunger up in the lifter is pretty weak but it will hold up the weight of the pushrod. When I have all of this free play out of them i then turn the nut the required preload amount. Personally I like 1/2 turn. When you turn the nut the additional preload amount you will notice one of two things if you had all the free play out. If the lifter is dry, you will see the plunger in the lifter move down a bit. (intake has to be off to see this) If the lifter is full of oil you will see the valve open a bit. It will slowly close as the lifter bleeds down. Ive been using this method for at least 25 years and have yet to have to re-adjust one after cranking the engine.
     

  5. buschandbusch
    Joined: Jan 11, 2006
    Posts: 1,293

    buschandbusch
    Member
    from Reno, NV

    thanks guys- I di not soak the lifters, I know I should have but I needed it done in one day, I flew back home and have to drive this thing home tomorrow. Bad idea rushing, I know.

    I did have plenty of assembly lube and a liberal coating of GM EOS lube. I went back one all of them and backed each off half a turn. I know I may need to readjust after 100 miles, so best not to be too tight yet.

    my main concern was just that adjusting the large number at once on one turn, and then the other half when it rotated over was that i could no longer spin the rod when adjusted on all the 2,4,6 and 8 valves, but could spin the 1,3,5, and 7 rods after adjustment. Is that normal? I did spin it over again to get TDC set right, and can now spin the 2,4,6,8 pushrods i adjusted, I'm just still wondering why the 2,4,6,8 felt different after adjustment?

    Oh, and I also used the up and down method to take all movement out, then set the nut down 1/2 turn.

    Thanks a bunch!
     
  6. SinisterCustom
    Joined: Feb 18, 2004
    Posts: 8,277

    SinisterCustom
    Member

    0 lash + 1/4 turn initial
    Warm up engine and adjust with valve cover off....loosen till it just clatters, tighten to quiet + 1/4 turn.....
    Use either a junk VC with the center cutout or some rocker arm oil deflectors.

    I ALWAYS do my final adjustments with the engine running at idle.
     

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