A question on setting valve lash
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A question on setting valve lash So I had some bad lifter ticking in my lt1 so I decided I'd change out the lifters to ls7 lifters. I have them installed and I tried to set the valve lash today. I used the method of turning the pushrods and tightening down the nut until the pushrods stopped rotating easily then I went a 1/4 turn. After I was done, on a few of them I was still able to rotate the rockers side to side enough that I could actually rotate the rocker almost all the way off the valve stem. Is this normal because there is no oil pressure? Before I replaced the lifters the rockers would move side to side but not actually rotate off the valve stem. And yes this is the first time I've even been this far into the motor so cut me some slack please! Thanks!
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Joined: Jul 2006
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From: Chattanooga, TN.
Here is a good "how to" on valve adjustment:
http://shbox.com/1/4th_gen_tech2.html#adjust_valves
Be sure to scroll down and read the whole article.
Hope this helps.
http://shbox.com/1/4th_gen_tech2.html#adjust_valves
Be sure to scroll down and read the whole article.
Hope this helps.
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Well the method I used to make sure the valves were closed and the lifter on the base of the cam was just make sure the lifters were all the way down. Doesn't that mean that I can set valve lash at that time?
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U want to ensure the lifters are on the base circle of the cam. They way i can tell is using the firing order 18436572 were every 90 degrees crank rotation 2 cyls are at TDC. So it would be like #1 & #6 both are TDC but only one of them is in compression with both vlvs closed and the other in overlap for exh/intk cycle, then 90 degrees later cyls #8 & #5 and with one with both vlvs closed and one in overlap, next cyls #4 & #7 etc, then Cyls #3 & #2. The cyl with both vlvs closed has both lifters on the base circle - this is the time to adj that cyl for lifter preload - do not touch the cyl with vlvs open.
This method ensures that the vlvs are closed and lifters are on base circle rather than just eyeballing the lifter/vlv is down and closed. Adj preload with the roll the p-rod method and your good to go. Sorry i dont know what preload the LS7 lifter takes but all the legacy hyd lifters used a full turn of preload.
This method ensures that the vlvs are closed and lifters are on base circle rather than just eyeballing the lifter/vlv is down and closed. Adj preload with the roll the p-rod method and your good to go. Sorry i dont know what preload the LS7 lifter takes but all the legacy hyd lifters used a full turn of preload.
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U want to ensure the lifters are on the base circle of the cam. They way i can tell is using the firing order 18436572 were every 90 degrees crank rotation 2 cyls are at TDC. So it would be like #1 & #6 both are TDC but only one of them is in compression with both vlvs closed and the other in overlap for exh/intk cycle, then 90 degrees later cyls #8 & #5 and with one with both vlvs closed and one in overlap, next cyls #4 & #7 etc, then Cyls #3 & #2. The cyl with both vlvs closed has both lifters on the base circle - this is the time to adj that cyl for lifter preload - do not touch the cyl with vlvs open.
This method ensures that the vlvs are closed and lifters are on base circle rather than just eyeballing the lifter/vlv is down and closed. Adj preload with the roll the p-rod method and your good to go. Sorry i dont know what preload the LS7 lifter takes but all the legacy hyd lifters used a full turn of preload.
This method ensures that the vlvs are closed and lifters are on base circle rather than just eyeballing the lifter/vlv is down and closed. Adj preload with the roll the p-rod method and your good to go. Sorry i dont know what preload the LS7 lifter takes but all the legacy hyd lifters used a full turn of preload.
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From: Las Vegas
OE cams have long slow ramps on the lobes. But i do know that when a pair of cyls are TDC one is under compression with both vlvs closed and lifters are on the base circle while the other cyl at TDC is in overlap with both valves open/lifters on the lobe ramp. I cant say that for any other vlv on other cyls though one or more maybe - but it would be a guess. The choice is yours.
It can be normal, yes. I'd suggest not turning the pushrod, but rather moving it up and down while tightening the adjusting nut until all slack is out of the pushrod and then tightening to your desired preload. Most accurate way is using the EOIC method as described on shoebox's site. All methods on that page work fine especially for a stock setup.
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Well damn... I thought my lifter tick would be fixed but I just started the car up and it's still there. A loud sewing machine sound on the drivers side. I'm pretty sure it's not an exhaust leak. Are there any other common problems that would make that sound?
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I had that tick as well when I set my preload at only 1/2 a turn (vs. a quarter of a turn for you). My step-father (an ASE certified Master Tech in all areas except for auto transmissions - he can work on them but he does not enjoy them) says one full turn of preload. We set mine up that way and (Ta-Da!) the tick disappeared!
I hope it's that easy for you as well.
I hope it's that easy for you as well.
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Man I really hope so. Although it was making this noise before I swapped lifters. I am now using ls7 lifters and from what I've read it's usually 1/4 to 1/2 turn. I'm so tired of it but I'm going to have to open it back up tomorrow. Thanks for the advice!
If the tick becomes louder when the engine is under load then it could be from an exhaust leak. Valvetrian ticks do not increase in volume when there is load. If the valves were adjusted correctly initially and the tick is still there it would not make much sense to just tighten them further. If the tick disappears it could be a mask of something else wrong. If it is confirmed there is no leak then I would suggest you take all the rockers and pushrods out and check them for abnormal wear as well as the valve tips. Also, a well adjusted valvetrain on a LT1 should sound like a sewing machine. There is going to be noise, but as long as that noise is uniform it is normal. If there is any one noise that stands out then it's time to investigate. You can also get an auto stethoscope to get the general location of where the noise is coming from.
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If the tick becomes louder when the engine is under load then it could be from an exhaust leak. Valvetrian ticks do not increase in volume when there is load. If the valves were adjusted correctly initially and the tick is still there it would not make much sense to just tighten them further. If the tick disappears it could be a mask of something else wrong. If it is confirmed there is no leak then I would suggest you take all the rockers and pushrods out and check them for abnormal wear as well as the valve tips. Also, a well adjusted valvetrain on a LT1 should sound like a sewing machine. There is going to be noise, but as long as that noise is uniform it is normal. If there is any one noise that stands out then it's time to investigate. You can also get an auto stethoscope to get the general location of where the noise is coming from.
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OP
if, after you settle the valve lash the "tick" is still there, check for cracked exhaust manifold/header. Especially if "tick" is louder on initial start-up and gets quieter when engine is warm but still there
if, after you settle the valve lash the "tick" is still there, check for cracked exhaust manifold/header. Especially if "tick" is louder on initial start-up and gets quieter when engine is warm but still there
