[Z06] ls7 comp trunion upgrade
11-04-2013, 01:18 PM
#41
Safety Car
Member Since: Aug 2009
Location: Chester County Pennsylvania
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2020 C5 of the Year Finalist - Unmodified
No. The trunnion is just a pivot point... any side-side activity would be due to off center loads induced either by the pushrod/rocker interface or the rocker/valve stem interface.
Should things happen to not be perfectly in alignment between pushrod, rocker arm pedestal, and valve stem tip then I'd think you'd want a little freedom of movement in the trunnion, wouldn't you?
Personally I suspect that may be why you see the occasional broken circlip on the CC upgrade... if the factory setup is not perfect in alignment, and when you constrain the rocker with a tight trunnion something has to give (the circlip).
If you loosen an old Gen I SBC rocker you can spin it 360 degrees on its stud. I'm not thinking lateral 'slop' is a big issue in the pushrod OHV design.
The side load that is of concern in that type of design is that imparted in line with the rocker arm, not perpendicular to it (assuming the lifter bores are machined in line with the valve guides, with the rocker pivot point in a mid-line location)... and that side load is simply the nature of the beast, regardless of trunnion or rocker tip. Wear pattern on the rocker pad and the valve stem tip will probably tell you if the rocker is having issues, in which case something more than a new rocker or new trunnion might be in order (something like a blueprint rebuild of the head or, in what should be an unusual case, the entire block).
Should things happen to not be perfectly in alignment between pushrod, rocker arm pedestal, and valve stem tip then I'd think you'd want a little freedom of movement in the trunnion, wouldn't you?
Personally I suspect that may be why you see the occasional broken circlip on the CC upgrade... if the factory setup is not perfect in alignment, and when you constrain the rocker with a tight trunnion something has to give (the circlip).
If you loosen an old Gen I SBC rocker you can spin it 360 degrees on its stud. I'm not thinking lateral 'slop' is a big issue in the pushrod OHV design.
The side load that is of concern in that type of design is that imparted in line with the rocker arm, not perpendicular to it (assuming the lifter bores are machined in line with the valve guides, with the rocker pivot point in a mid-line location)... and that side load is simply the nature of the beast, regardless of trunnion or rocker tip. Wear pattern on the rocker pad and the valve stem tip will probably tell you if the rocker is having issues, in which case something more than a new rocker or new trunnion might be in order (something like a blueprint rebuild of the head or, in what should be an unusual case, the entire block).
OK, I get where you are coming from. So, without going the route of machining the heads to accept the Crower set up, is there any acceptable roller rocker that will not have too much mass to induce valve float, or have to change the springs to offset the mass? I am skeptical of Yella Terra, because I never could get them to answer my questions about their product.
11-16-2013, 06:44 AM
#42
Burning Brakes
rocker arm bolts
Finished the Comp Trunion Upgrade / swap, and all I can say is WOW
Regardless of whether or not your C6 Z06 falls into the dreaded fail date of the bad batch of rocker bearings, EVERYONE should do this upgrade. Hopefully I got a video of what my Z sounded like before the upgrade, because the end results are amazing. The Comp trunion setup has less side-play or movement and has resulted in a FAR healthier sounding motor.
None of my factory rockers had failed or dropped any bearings and I'm indeed within the dreaded fail date range. But the factory side to side play between the rocker-arm and trunion was far too excessive (IMO). The end results with the Comp setup is AWESOME. This upgrade is more than worth it. Not only is it a more solid setup setup, but it provides peace of mind, and makes the motor sound 10-times better.
I'll be posting an extensive and detailed how to as soon as I get a few other things taken care of
Regardless of whether or not your C6 Z06 falls into the dreaded fail date of the bad batch of rocker bearings, EVERYONE should do this upgrade. Hopefully I got a video of what my Z sounded like before the upgrade, because the end results are amazing. The Comp trunion setup has less side-play or movement and has resulted in a FAR healthier sounding motor.
None of my factory rockers had failed or dropped any bearings and I'm indeed within the dreaded fail date range. But the factory side to side play between the rocker-arm and trunion was far too excessive (IMO). The end results with the Comp setup is AWESOME. This upgrade is more than worth it. Not only is it a more solid setup setup, but it provides peace of mind, and makes the motor sound 10-times better.
I'll be posting an extensive and detailed how to as soon as I get a few other things taken care of
Anyone else have this issue? Haven't seen it mentioned before.
