vvlf

True, but at that point the rockers have already been torqued down and secured to their factory spec of 22 ft-lbs.

What were talking about is the re-installation of the rockers, and re-installing them with the valves open would cause tension/pressure resulting in an incorrect torque spec reading when tightening down the rocker mounting bolts

C6 Mayhem

It requires less than 22 lbs to tighten the rocker bolt until the rocker seats against the head. In fact you can tighten the bolt and compress the spring using a stubby 3/8 ratchet. There's more than adequate thread engagement on the bolt and there's very little spring pressure when first starting to compress the spring while thread engagement is minimal. Since tightening the bolt requires less than the required torque spec there is no excessive wear on the aluminum threads. And finally, since the bolt doesn't get tightened until after the rocker is seated against the head, installation of the rocker while not on the base circle does not affect accuracy when tightening the bolt to spec.

vvlf

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

Olddudesrule

Did you also upgrade your springs at the same time? I did, but mainly because of the cam upgrade. I also figured it was wise to do even without the cam.

triblk6spd

The Comp trunion upgrade was one of the first mods I did when I got my car. Seems to be working great...last 5000mi. If found the Comp bolts to be way too long as well so I reused my stockers.

Dirty Howie

DH

sydneyACE

Anyone have any feedback regarding using the trunion upgrade with high-lift cams or high-rpm applications?

Just currious how well they hold-up.
If they can handle high stress applications well, they would be the most economical rocker solution by a lot.

LS9Drew

where is everyone getting these from?

CanadaGrant

Comp Cams or any Comp Dealer such as Jegs or Summit. They are even on fleabay under LS trunion upgrade. About 135 bucks for the kit.

LS9Drew

Ok thanks found them on summit
Also Would you guys suggest changing the Pushrods as well or Springs while doing the Trunion upgrade?
7.800 5/16 or would I want 3/8?
http://www.summitracing.com/parts/TFS-21407800/

jedblanks

Are you running stock cam?

If so, I would take your stock pushrods and roll them to check they are true and then leave them alone if they are.

vvlf

Take note of the direction of the pushrods when you do this as a mated surface has been created between each end of the pushrod to its respective surface it comes in contact with (cam or rockers).

It wouldn't be the end of the world if they got flipped around when removing and reinstalling, its just better to reinstall them as they came out. Valve lash......net build.......yada yada yada

LS9Drew

Ya I have stock cam

1972bluelt1

Shouldn't the tightening sequence be different between an LS7 and an LS1. the timing order is 18726543 vs. 18736542. If you compare a gen I sbc to a LS1 (4/7 swap) and compare the sequence it makes sense. Ls7 vs LS1 is a 3/2 swap. Am I making sense?

American Heritage

If in doubt or worried about the threads or incorrect torque readings then just make sure each rocker you are tightening is on base circle and your good to go. Although you can tighten them down even with the valves open, no harm done.

Too-Fast

I have been pondering this whole exhaust valve issue for quite some time, and am convinced, that a major contributor to the problem is with the rocker arms; while the stock rockers provide low mass, they allow a lot of friction and side load build up; this upgrade seems like a great compromise. Has anyone investigated whether or not installing this upgrade voids the factory power train warranty? My car has a lot of warranty left and I would not want to void the warranty.

Mark2009

A trunnion upgrade will do nothing for "friction and side load". If you want to address those issues then you'll have to go to a roller tipped rocker, which then introduces all other kinds of issues.

In fact, there is no evidence that the trunnion upgrade will do anything useful at all. Yes, I know the factory trunnions are often perceived as 'loose', but no one has ever reasonably explained or demonstrated how that is a 'problem'.

'06 Quicksilver Z06

The only thing that I can see that a trunion upgrade will do for you is eliminate the needle bearings if you are concerns about those.

And then only if you do the C.H.E. trunion upgrade, as the Comp upgrade still uses bearings.

Too-Fast

OK, thanks for responding, however just the fact that the rockers are restricted in movement should reduce any spurious movement activity, that could contribute to side load, no?

Mark2009

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).