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Well mine were never pulled before either and the GM logo was upside down on both sides. I have the pedestal stand off now and I cannot see a difference from one side to the other as they look indentical so it should have no effect on rocker arm geometry at all.
Update: new cat and it still wasn’t running right, so I had it towed home to do further investigation on my own. Pulled codes and saw a P0106 for MAP sensor which was weird. After running it for a minute, took a temp gun to the manifold and 8 and 4 were hot, 6 was cold, and random cylinders on the driver side were also cold. Did a compression test and had 130-150psi on all cylinders except 6, which had 0. Pulled rocker cover and found the exhaust valve spring was broke and pushrod slightly bent. Picking up a new spring and pushrod today at 3. My theory is the exhaust valve hung open 1/4 inch was pushing spent gasses back into 6 and back into the intake manifold every time 6 went to intake, causing the random misfires on other cylinders. Fingers crossed it’s fixed in a couple hours.
What was happening is the exhaust valve was not opening because of the bent push rod. When the piston comes up on exhaust stroke the exhaust valve did not open therefor creating compression. When the intake valve opened the pressure goes into the intake instead of the exhaust. A lot of times when this happens you can hear it popping in the intake manifold and TB.
Well mine were never pulled before either and the GM logo was upside down on both sides. I have the pedestal stand off now and I cannot see a difference from one side to the other as they look identical so it should have no effect on rocker arm geometry at all.
What you say makes sense.
It looks like all it does dimensionally is space the rocker up a set amount vertically.
The bolt locates it in one spot in the horizontal plane.
So it would appear to not make a difference operationally.
What was happening is the exhaust valve was not opening because of the bent push rod. When the piston comes up on exhaust stroke the exhaust valve did not open therefor creating compression. When the intake valve opened the pressure goes into the intake instead of the exhaust. A lot of times when this happens you can hear it popping in the intake manifold and TB.
What I think actually happened is the spring broke, rotates slightly and jammed itself between the remaining spring, reducing it’s allowed travel. Then the pushrod came up, the rocker hit its limit on the broke spring, and bent the pushrod.
what I can’t explain is the broken spring. I never saw the cat with my own eyes to see how clogged it was, but theoretically a clogged cat would try to push an exhaust valve open, not closed, so I can’t figure out what happened first.
