Crooked Rocker Arm?
10-04-2010, 09:46 AM
#1
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Crooked Rocker Arm? I had the valve cover off the passenger side of my LY6 this weekend, and noticed that one of the rocker arms seemed crooked (the middle one in the first picture). My question is will this be ok to run as it is, or is it severe enough that I need to adjust it? I assume that I am the first person to remove the valve cover and so it must have come this way, which also means that the motor has run about 7000 miles with it this way.
Any info is appreciated. Thanks.
From front of head
From back of head
Any info is appreciated. Thanks.
From front of head
From back of head
10-04-2010, 10:23 AM
#2
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does that picture make it look like someone did some griding on there or does it looks as bad in person too? I mean maybe thats normal but I never noticed that on the 32 stock rockers those I have... maybe i just need to go look 
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10-04-2010, 02:42 PM
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AFAIK, this happens when something is not installed correctly or properly.
I purchased an engine from a shop here in houston, only to find out that all the engine work was done half ***. One head was stock and one had been apart at some point in time. The shop had assembled the head with impact guns and didn't bother to align the rockers. 3 out of 8 were exactly how you show in your picture. I simply replaced the stand underneath the rockers and assembled with care. They will still try to move upon assembly due to the bolt being twisted.
If anyone could chime in on how this could affect the rocker/valve wear patterns... or provide a better reason to how and why this occurred in his situation... I don't know the extent of "damage" that could be done by this misalignment. I don't see a lot of threads on it.
I purchased an engine from a shop here in houston, only to find out that all the engine work was done half ***. One head was stock and one had been apart at some point in time. The shop had assembled the head with impact guns and didn't bother to align the rockers. 3 out of 8 were exactly how you show in your picture. I simply replaced the stand underneath the rockers and assembled with care. They will still try to move upon assembly due to the bolt being twisted.
If anyone could chime in on how this could affect the rocker/valve wear patterns... or provide a better reason to how and why this occurred in his situation... I don't know the extent of "damage" that could be done by this misalignment. I don't see a lot of threads on it.
10-04-2010, 07:20 PM
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Thanks for all the replies.
I got the motor from a parts yard to swap into my Nova so I don't know the exact history, but with 7xxx miles in a van I wouldn't expect anybody had torn into the motor before me, but then again I wouldn't think the factory would send it out like that either.
Anyway, so the consensus is that I need to adjust it straight? Also, I have read that the bolts need to be torqued to 22 lbs, is that correct?
Thanks
I got the motor from a parts yard to swap into my Nova so I don't know the exact history, but with 7xxx miles in a van I wouldn't expect anybody had torn into the motor before me, but then again I wouldn't think the factory would send it out like that either.
Anyway, so the consensus is that I need to adjust it straight? Also, I have read that the bolts need to be torqued to 22 lbs, is that correct?
Thanks
10-04-2010, 08:40 PM
#12
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Thanks for all the replies.
I got the motor from a parts yard to swap into my Nova so I don't know the exact history, but with 7xxx miles in a van I wouldn't expect anybody had torn into the motor before me, but then again I wouldn't think the factory would send it out like that either.
Anyway, so the consensus is that I need to adjust it straight? Also, I have read that the bolts need to be torqued to 22 lbs, is that correct?
Thanks
I got the motor from a parts yard to swap into my Nova so I don't know the exact history, but with 7xxx miles in a van I wouldn't expect anybody had torn into the motor before me, but then again I wouldn't think the factory would send it out like that either.
Anyway, so the consensus is that I need to adjust it straight? Also, I have read that the bolts need to be torqued to 22 lbs, is that correct?
Thanks
22lbs should be your pre-load.
This is how I did mine:
Mark the top of the vlv with a black marker. Install rocker arm torque to 22ft lb. Spin motor. Check were marker on top of vlv is missing from. If its dead center reinstall to 22 ft lb. If its towards the outside of the motor you need less torque if its toward the inside you need more torque.
Anyone correct me if you have a better procedure.
10-04-2010, 10:00 PM
#13
AFAIK, this happens when something is not installed correctly or properly.
I purchased an engine from a shop here in houston, only to find out that all the engine work was done half ***. One head was stock and one had been apart at some point in time. The shop had assembled the head with impact guns and didn't bother to align the rockers. 3 out of 8 were exactly how you show in your picture. I simply replaced the stand underneath the rockers and assembled with care. They will still try to move upon assembly due to the bolt being twisted.
If anyone could chime in on how this could affect the rocker/valve wear patterns... or provide a better reason to how and why this occurred in his situation... I don't know the extent of "damage" that could be done by this misalignment. I don't see a lot of threads on it.
I purchased an engine from a shop here in houston, only to find out that all the engine work was done half ***. One head was stock and one had been apart at some point in time. The shop had assembled the head with impact guns and didn't bother to align the rockers. 3 out of 8 were exactly how you show in your picture. I simply replaced the stand underneath the rockers and assembled with care. They will still try to move upon assembly due to the bolt being twisted.
If anyone could chime in on how this could affect the rocker/valve wear patterns... or provide a better reason to how and why this occurred in his situation... I don't know the extent of "damage" that could be done by this misalignment. I don't see a lot of threads on it.
There may be a seat under the arm that needs to be replaced to make it go straight.
22lbs should be your pre-load.
This is how I did mine:
Mark the top of the vlv with a black marker. Install rocker arm torque to 22ft lb. Spin motor. Check were marker on top of vlv is missing from. If its dead center reinstall to 22 ft lb. If its towards the outside of the motor you need less torque if its toward the inside you need more torque.
Anyone correct me if you have a better procedure.
22lbs should be your pre-load.
This is how I did mine:
Mark the top of the vlv with a black marker. Install rocker arm torque to 22ft lb. Spin motor. Check were marker on top of vlv is missing from. If its dead center reinstall to 22 ft lb. If its towards the outside of the motor you need less torque if its toward the inside you need more torque.
Anyone correct me if you have a better procedure.
As John at Scoggin suggested, the rocker bolt likely just backed out causing the rocker to drift from its centered position when properly seated in the pedestal. Hopefully no thread damage has been done.
Just bump the motor over till the affected cylinder has that valve fully closed so the load is off of the rocker, then remove it and check for unusual wear. If it looks ok, reassemble and as you hand tighten the rocker it should self-align when seated against the pedestal.
Torque the bolt to 22 ft/lbs and you're good to go.
If the rocker or pedestal look worn I would replace them, especially since both items are stupid cheap.
DO NOT run the engine until this is fixed.
Good Luck!
Jim
10-05-2010, 09:10 AM
#14
There may be a seat under the arm that needs to be replaced to make it go straight.
22lbs should be your pre-load.
This is how I did mine:
Mark the top of the vlv with a black marker. Install rocker arm torque to 22ft lb. Spin motor. Check were marker on top of vlv is missing from. If its dead center reinstall to 22 ft lb. If its towards the outside of the motor you need less torque if its toward the inside you need more torque.
Anyone correct me if you have a better procedure.
22lbs should be your pre-load.
This is how I did mine:
Mark the top of the vlv with a black marker. Install rocker arm torque to 22ft lb. Spin motor. Check were marker on top of vlv is missing from. If its dead center reinstall to 22 ft lb. If its towards the outside of the motor you need less torque if its toward the inside you need more torque.
Anyone correct me if you have a better procedure.
Preload is how much the pushrod pushed down the lifter cup after 0 lash.
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10-05-2010, 09:15 AM
#15
*The LS engine family uses net lash rockers, so the only way to adjust the sweep of the rocker tip is to shim the rockers or pedestals.
As John at Scoggin suggested, the rocker bolt likely just backed out causing the rocker to drift from its centered position when properly seated in the pedestal. Hopefully no thread damage has been done.
Just bump the motor over till the affected cylinder has that valve fully closed so the load is off of the rocker, then remove it and check for unusual wear. If it looks ok, reassemble and as you hand tighten the rocker it should self-align when seated against the pedestal.
Torque the bolt to 22 ft/lbs and you're good to go.
If the rocker or pedestal look worn I would replace them, especially since both items are stupid cheap.
DO NOT run the engine until this is fixed.
Good Luck!
Jim
As John at Scoggin suggested, the rocker bolt likely just backed out causing the rocker to drift from its centered position when properly seated in the pedestal. Hopefully no thread damage has been done.
Just bump the motor over till the affected cylinder has that valve fully closed so the load is off of the rocker, then remove it and check for unusual wear. If it looks ok, reassemble and as you hand tighten the rocker it should self-align when seated against the pedestal.
Torque the bolt to 22 ft/lbs and you're good to go.
If the rocker or pedestal look worn I would replace them, especially since both items are stupid cheap.
DO NOT run the engine until this is fixed.
Good Luck!
Jim
There may be a seat under the arm that needs to be replaced to make it go straight.
22lbs should be your pre-load.
This is how I did mine:
Mark the top of the vlv with a black marker. Install rocker arm torque to 22ft lb. Spin motor. Check were marker on top of vlv is missing from. If its dead center reinstall to 22 ft lb. If its towards the outside of the motor you need less torque if its toward the inside you need more torque.
Anyone correct me if you have a better procedure.
22lbs should be your pre-load.
This is how I did mine:
Mark the top of the vlv with a black marker. Install rocker arm torque to 22ft lb. Spin motor. Check were marker on top of vlv is missing from. If its dead center reinstall to 22 ft lb. If its towards the outside of the motor you need less torque if its toward the inside you need more torque.
Anyone correct me if you have a better procedure.
Also there is no seat under a stock rocker arm that can be adjusted on a stock setup. The entire stand has individual pedestals on them that align the rocker and provide the proper seat height for them. The stand and the pedestal are one piece. No adjustment there. You can shim the stands, but you would not have that option on an all stock engine, nor should it need it.
Have you looked at a rocker stand?
Last edited by Beau@SDPC; 10-05-2010 at 09:25 AM.
10-29-2010, 06:42 PM
#17
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Alright, I finally got around to fixing this, and I was just checking out the other rockers, and just a couple look slightly off center as well. None near as bad as the one pictured above, and I probably won't worry with fixing them, but I was just curious if GM sends them out this way? Would that be within their tolerances?
11-12-2010, 08:15 PM
#18
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Going to try to bump this up...
Just wondering what an acceptable position is for the tip of the rocker arm (say, in relation to the valve stem, or valve lock, etc.)?
For example, a different arm is off center an amount to where when looking from above, the arm tip covers up the far left edge of the valve lock. Like the first or second picture, just not quite as bad (it covers the entire valve stem).
Thanks
Just wondering what an acceptable position is for the tip of the rocker arm (say, in relation to the valve stem, or valve lock, etc.)?
For example, a different arm is off center an amount to where when looking from above, the arm tip covers up the far left edge of the valve lock. Like the first or second picture, just not quite as bad (it covers the entire valve stem).
Thanks
