hobobiker

I'm searching through the forum threads, but before I put this new-to-me C5 with almost 100k miles on a dyno I'd like to make sure it doesn't still have the stock springs. Car has a big cam and I would HOPE that whoever did that changed the springs and trunions as well, but if you've seen my other posts they reused the stock harmonic damper and OEM bolt, which caused me a lot of work and the need to second-guess everything that's been done to the old girl. Wanted to check the trunions while I'm in there as well. I see the trunions have circlips, but I need to check if stockers had them as well. I know the Straub kits use them.

Valve cover definitely needs a cleanup..



I'm hoping that one of the more seasoned techs here can eyeball these pics and at least tell me whether the springs/trunions look stock. Since I have no idea what cam is in here, maybe I'll put a dial indicator on one of the rockers and measure the lift just to get a baseline...

Smoken1

The stock ones have no clips but those still may be the old style comp ones with the bearings in them. Take one apart and see what you got

evolmotorsprt

neutron82

looks like dual springs and a comp trunnion kit, definitely not stock... I would be concerned about the trunnions, they are well known to fail even more so on cammed cars... I made a thread a year or 2 ago that documented the failure and repair pretty well but I think most of the pics were lost due to photobucket... I would recommend getting those out at least to inspect them and replace if needed

hobobiker

Thanks guys. I didn't press the trunion out, but I did pull a rocker and removed a circlip. Verified that they do indeed have INA bearings in them.



Also got a better look at the springs with the rocker off. Someone definitely installed a dual-spring setup


I pulled a pushrod to take a look as well. Looks like 7.400 .080. I'll need to do a little homework on these.

hobobiker

Okay, based on what I found yesterday and some forum reading last night, I'll be ordering a trunion upgrade today. What I have look to be Comp Cams with INA needle bearings, and I think I'm in the camp of wanting some bushing-type trunions instead. Will be comparing Straub vs. CHE today. If there are others I should be considering as well, say the word.

My end game is just to measure the lift on the cam and dyno the car so I have a baseline of what has been done, then just drive it as a sunny-day cruiser with some occasional "foot to the floor" fun. I just want to address any weak points first.

Thanks everyone - this forum is a wealth of knowledge and help...

Hobo

hobobiker

Well, after more reading/searching this morning I decided I probably couldn't go wrong with either the CHE or Straub products. Ordered the CHE kit from Texas Speed and the Powerhouse install tool from Summit. I'll take some pics of the install and of the existing trunions that I remove (although I'll have no idea how many miles are on them).

Hobo

leadfoot4

Excellent choice!

After hearing about some of the failures of the OE "trunnions", 4-5 years ago, I installed the Comp Cams trunnions/bearings in my car, even though I don't drive it very hard. Then after hearing about the wear issues of the Comp trunnions, I replaced them with the Straub bushings, about 2 years ago.

I initially considered the CHE bushings, but when they first offered them, the only way that you could obtain them, was to send your rockers to CHE, and they'd do the retrofit, then send them back to you. Downtime of the car, as well as overall cost was an issue for me, as I think that CHE wanted something in the $400-500 range, if I remember correctly.

hobobiker

Thanks for catching my spelling error! Tool should arrive today and the CME stuff tomorrow. I'll post pics of the process. While I'm at it I hope to put a dial indicator on a rocker and measure the cam lift just to let me know SOMETHING about the bumpstick. I wish manufacturers would stamp the cams on the front end of the motor. If that were the case I would have been able to identify it when I was replacing the timing chain, damper, and oil pump.

leadfoot4

Actually, I put the word trunnions in quotes, not to refer to spelling, rather that I sort of question the OE "pivoting devices", as to whether or not they are accurately described as trunnions. They're a sort of triangular device, that only allow for a limited amount of rotation as opposed to the Comp Cams or CHE/Straub's 360* of rotation.

Along that line, this is where the trouble with the OE trunnions seems to develop. Either big cams, that need more angular rotation from the rocker arm, or the added strain of stiffer valve springs, seem to be what destroys the OE "trunnions".

Since I still have a stock cam and springs, in retrospect, I probably would have been just fine with the OE set-up. But since I like to "tinker", and had some spare time, I did the upgrade.

Rx7Rob

I have the CHE trunnions. No installation tool required. They just slip together, nothing is pressed.

They are very nice!

hobobiker

Yeah, I ordered the tool when I thought I would be going with Straubs. I wrench on bikes/cars/planes as a hobby anyway so one more tool in the toolbox isn't a bad thing. LOL! And, I'll still be pressing the old trunnions out so the tool will probably come in useful there.

Glad to hear the good report on the CHEs!

evolmotorsprt

ArmchairArchitect

On a stock LS6 (Z06) does one need to worry about the stock trunions failing, or is this more for modded cars? What are the symptoms of them going bad, and what could potentially happen to the engine if they fail?

Already had the valvesprings replaced with new OEM ones.

jvettman

My understanding is when stock trunions fail, needle bearings gut your motor...or at least could.

evolmotorsprt

leadfoot4

There are a LOT of Chevy/GMC pickup trucks running around for THOUSANDS of miles, with stock engines, and I'd bet that none of them have updated rocker arms. As I said previously, I probably didn't need to upgrade mine, but did so "just because". I will say, however, the valvetrain is quieter with the Straub bushings.

hobobiker

From what I've seen and read, cams that require stiffer valve springs (i.e. higher open and closed pounds of pressure) are a major contributor to the bearings failing. My car has a big cam and dual valve springs, and since I've already addressed some things that the previous owner(s) did incorrectly I chose to take a look at my trunnions. To make matters worse, mine aren't the stockers but instead look to be the Comp Cams versions that are known to wear prematurely - so I absolutely wanted to change them out.

Best of luck with whatever you decide...

Hobo

leadfoot4

But keep in mind, even if the Comp trunnions start to degrade, they won't spit out the needle bearings, like the OE parts could, as the Comp's bearings are captured. However, that doesn't mean that metal particulate wont wind up in the oil...

hobobiker

Agreed. It was the multiple pictures of the metal wearing off of the trunnions that gave me heartburn on the Comps. I would rather have bronze/brass from the bushings floating around in my oil than steel.

Once my new ones come in I'll post pics of what the Comps looked like when I tore them down. It's possible I have a good set that's not wearing, but I'm not willing to risk chancing it vs. the cost of a new/rebuilt engine.