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LT1-LT4 Modifications
1993-97 Gen II Small Block V8

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Old 08-05-2007, 01:02 AM   #1
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Default valve lash setting?

Ok I've read several articles about setting valve lash but what I'm confused about is where zero lash. Is it where you can no longer move the pushrod up and down or you can no longer spin it. They say tighten where you feel resistance but what is really resistance?? Please help I'm right in the middle of this project. The rockers are GM LT4 Hot Cam kit 1.6.
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Old 08-05-2007, 01:18 AM   #2
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Zero lash is when you go from having slack between the lifter, pushrod and rocker arm, to the exact point of no slack. The lifter needs to be on the base of the lobe when setting valve lash. When a cylinder is at TDC, both lifters should be at the bottom of their travel (base of the cam lobe).

Gauging zero lash by hand is not an exact science. When setting the valve lash with the engine not running, you can get close enough by doing the "spin the pushrod" method. Loosen the rocker arm until you can feel slack in the pushrod to rocker arm. Spin the pushrod with your fingers while tighening the rocker arm back down. When you BEGIN to feel drag while spinning the pushrod, you are at zero lash. Once zero lash is reached, stop and add your preload. DO NOT go back and try to feel the adjustment. The lifter will immediately begin to bleed down a little. Tension on the pushrod will relax and this will make it seem like your adjustment did not work. If you want to recheck zero lash, you must loosen the rocker arm nut and tighten it down again while spinning the pushrod as before. At that point you want to set the preload and LEAVE IT ALONE.


this info is from www.shbox.com hope it helps
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Old 08-05-2007, 03:54 AM   #3
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Is the preload where you turn the nut 1/2 or 3/4 turn?? Awsom info. by the way!!
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Old 08-05-2007, 03:58 AM   #4
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also when you feel drag while spinning the push rod do you want it where you can no longer spin it or would that be to much?
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Old 08-05-2007, 10:18 AM   #5
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engine running method is easier......loosen your rockers till they clack, slowly tighten till the rocker quits clacking, once the clacking stops 1/4-1/2 turn and lock the rocker
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Old 08-05-2007, 10:41 AM   #6
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The spin the pushrod method almost always results in too tight an adjustment.

With the polylocks of roller rockers zero lash is pretty easy to find, run the nut down till it just contacts the rocker and then play around trying to move the pushrod inline with the lifter/rocker you will soon see what I mean.
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Old 08-05-2007, 01:13 PM   #7
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OK guys thanks for your help but I really need help! First of all these rockers are new along with the cam so I can't start it up and adjust from there. Second this valve lash is pissing me off because while tightning the nut there's very little resistance then bam now the pushrod won't turn. Do I take it to that point then a 1/4 turn?? At this point the pushrod won't turn at all so is this too tight?? Also some of the locks recesses down into the nut more than others??? Do that mean something? I would think if everything is adjusted right all the locks would be equal?? I also installed new roller lifters so I don't know if that plays a part too...
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Old 08-05-2007, 01:24 PM   #8
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Quote:
Originally Posted by 96capricemgr
The spin the pushrod method almost always results in too tight an adjustment.

With the polylocks of roller rockers zero lash is pretty easy to find, run the nut down till it just contacts the rocker and then play around trying to move the pushrod inline with the lifter/rocker you will soon see what I mean.
I've tried this method but after the nut just contacts the rocker you can't spin or move the pushrod at all??
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Old 08-05-2007, 09:27 PM   #9
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Quote:
Originally Posted by 96capricemgr
The spin the pushrod method almost always results in too tight an adjustment.

With the polylocks of roller rockers zero lash is pretty easy to find, run the nut down till it just contacts the rocker and then play around trying to move the pushrod inline with the lifter/rocker you will soon see what I mean.
+1 its so easy with polylocks so glad I switched
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Old 08-05-2007, 10:28 PM   #10
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how do you get it to tdc ? sorry im 17 and a beginer
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Old 08-05-2007, 11:22 PM   #11
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Quote:
Originally Posted by 93blacktransam
how do you get it to tdc ? sorry im 17 and a beginer
spin the motor over with ratchet on the crank bolt. You dont have to have it at tdc to adjust the valve lash. just make sure that the lifter is on the back side of the cam lobe (bottom of its bore). Then do you valve lash setting from there.
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Old 08-05-2007, 11:37 PM   #12
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so what all do i have to have apart to spin it and i dont get what your saying with the
"just make sure that the lifter is on the back side of the cam lobe (bottom of its bore)."
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Old 08-05-2007, 11:56 PM   #13
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I set mine 3/4 past 0 lash.
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Old 08-05-2007, 11:56 PM
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