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Thread: 350 rocker arm torque

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    350 rocker arm torque

    i got a little problem. torqued down my rocker arms on my motor to 50lbs like it said to on the specs. now i figured there was a special way to do it but i couldnt seem to find it on the net so i just did it my way. turned the motor over for a half second and all the rods either broke or bent. it ok though they were old and i figured i should use them for my experiment rather than the new ones. does anyone know how to properly torque the rockerarms on a 350 chevy so the rods dont bend/break. im guessing the valves need to be in a certain position or something. need imput ASAP

    thanks
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    All the one's I have done from the factory (350 chevy) have been adjustable....I've never tightened them all the way down.

    One way is to run them all down till the lifters were slightly loose, fire it up and snug each one till the lifter quieted down....then go 1/4 turn more. Done.(There is a more technical way of doing it, but if you are asking this question to begin with, it's probably better to go with the easier way for now)


    If you cranked them all down you effectively jammed the valves into the pistons....I can see bent pushrods, bent valves, etc.

    Walk away from that motor and start over.
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    The way we were taught was, with one hand, play with the push rod, wiggle it up and down while with your other hand you slowly tighten the rocker down. Keep doing this until the push rod stops rattling around and then tighthen it a 1/4 turn more. Then your set.
    I have never herd of a specific torque setting for rockers, but then again, I am stupid and dont know much, I could easily be wrong.

    I would think that your valves are pretty messed up now. I would assume the push rods are pretty bent up and junk. You may have even gouged the piston tops too (you said you didnt it crank the motor long so there is hope for the valves and pistons). Motor probably needs a rebuild now, I would at least pull the heads and inspect for damage. You said something was old??? Did you mean the heads, the motor or the push rods. And so you know for the next time (as these pushrods are now junk), you want to keep the rods in order. It is a good idea to put them back on the same rocker they came from.
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    Quote Originally Posted by Double-a
    The way we were taught was, with one hand, play with the push rod, wiggle it up and down while with your other hand you slowly tighten the rocker down. Keep doing this until the push rod stops rattling around and then tighthen it a 1/4 turn more. Then your set.
    .

    This can work as well, but you have to make sure your lifters are pumped up....If they have bled down any at all while cycling through the firing order to set them, you can get them too tight as well.

    Again, I like setting them with it running.....Pretty fool proof.....Can be a tad messy, but there is less chance of over tightening them if you are unsure of yourself.

    Obviously Double-a has done this before and it isn't an issue for him....If you dont' know what lifter bleed down is, I would do them with it running....If you do know what lifter bleed down is and what causes it, his way will work for you as well.
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    Member Forum Member crazi429's Avatar
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    yep big oops there the valve on a small block chevy are adjustable if you got lucky you may have only bent the push rods but other wise you have bent valves. I have seen then done several times before only damage is the bent push rods. You can do a leak down test to see it the valves are still sealing. if they are then get new push rods and you can do either a running adjustment or a cold adjustment. I have been doing cold adjustment for many years with out any problems.
    Bring engine to tdc #1 on the firing stroke and then loosen both #1 rocker arms until play is felt in push rods. Now slowly tighten the rokers arm nut till no play is felt in the push rod then tighten a additional 1/2 to 1 turns. now with engine in this position you can adjust intake valves on cyl. 1 2 5 7 and exhaust on 1 3 4 8 now rotate engine 1 full turn till #6 is on tdc of the firing stroke and adjust intakes 3 4 6 8 and exhaust 2 5 6 7
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    Crazi429 is correct. Thats how ya do the push rod engines. There ain't no torque spec you just gotta feel it. Then you run it awhile and readjust them if you want to be totally sure, but once should be fine and thats how I do it.

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    I set my rockers up this was and got all but one of them too tight. And yes i soaked the lifters in oil and primed the oiling system. its more fool proof to set them up loose with the engine off and tighten them down when it is running.

    Quote Originally Posted by Double-a
    The way we were taught was, with one hand, play with the push rod, wiggle it up and down while with your other hand you slowly tighten the rocker down. Keep doing this until the push rod stops rattling around and then tighthen it a 1/4 turn more. Then your set.
    .
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    Rocker Arms

    On a SB V-8, you have to have the #1 piston at TDC. And then you can tighten the EXHAUST rocker arms on the #1, 3, 4, 8 pistons; and the INTAKE rocker arms on the #1, 2, 5, 7 pistons.

    Then rotate the engine one full rotation, till TDC. This is the #6 firing position. Then you can tighten the EXHAUST rocker arms on the #2, 5, 6, 7 pistons and INTAKE rocker arms on the #3, 4, 6, 8 pistons.

    Do not over tighten. There's a couple of other ways to do this. But, this'll get you in the ball park.

    Good luck,

    Blazing 72

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    ok the problem with the torque specs was he read them for the rocker arm STUDS. not good. the engine was in a few peices when we turned it over. it couldnt fire b/c the distributor wasnt in and all that. the pistons and valves are fine or at least it looks like it. the tally is one broke rod and 4 bent rods the rest are fine. i got new ones now and will try it later. thanks for the help.
    Anthony
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    Crazi429 and Blazin72 re correct but I found this to be easier.
    This is directly from Crane Cams web-site...... i followed this, worked perfectly!
    Hope this helps..... check out Crane Cams web-site, lots of good info on how to break in a new cam properly also.

    Adjusting Hydraulic Lifters for Proper Preload

    In order to adjust the preload, the lifter must be properly located on the base circle or "Heel" of the lobe.
    At this position the valve is closed and there is no lift taking place. You will need to watch the movement of the valves to determine which lifter is properly positioned for adjusting.

    1. Remove the valve covers, and pick a cylinder that you are going to set the preload on.

    2. Hand rotate the engine in its normal direction of rotation and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)

    3. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)

    4. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at "Zero Lash". Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.

    5. Continue to hand turn the engine, watching that same intake. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.

    6. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.
    Last edited by 78GMC4x4; 03-05-2007 at 09:06 PM.
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    Dang this is an old post.

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