When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It really depends on who the favorite is this week on LStech. Next week it will be different.
I mean, has anyone actually seen an engine failure that has been positively attributed to the comp trunnion wear?
I mean the solution may be to simply treat the rocker arm trunnions on stock rockers as wear items on a non-stock valvetrain, regardless of what you go with.
That brinelling wear is from constant repetitive motion over the same spot, exacerbated from lack of lubrication. Like what you would see in a worn out u-joint.
You never said what this guy meant when he said "locking up" over .600 or .630 lift. WTF does that even mean?
Kenny said the stock rockers go over the arc they were designed for when you go over .600 lift. When the rocker does this they will tend to lock up. Meaning they will hang when the valve is full open. Almost like when you don't have enough spring pressure and the lifter leaves the closing side of the cam lobe at high rpm.
They wear as soon as you start using them. By design. The only thing this thread and others show is that such wear takes place over a much shorter period of time than advertised.
i would think any application that uses higher than the stock spring pressure and an aggressive cam lobe is going to put more stress on the rocker trunnion, regardless of the design of the trunnion.
absolutely. The more spring pressure, higher rpm you go will have more wear. To help slow the wear would be to go with a roller tip rocker to alleviate the pressure on the trunnion caused by the pad on a stock rocker scrubbing over the top of the valve stems.
My brother runs a 1100 hp BBC with an .850 lift cam and 350 lb. Spring at Closed seat pressure. He has to get his T&D shaft rockers rebuilt around 400 runs. 1/8 mile. That's not including the ones he randomly finds bad during maintenance.
Kenny said the stock rockers go over the arc they were designed for when you go over .600 lift. When the rocker does this they will tend to lock up. Meaning they will hang when the valve is full open. Almost like when you don't have enough spring pressure and the lifter leaves the closing side of the cam lobe at high rpm.
There is a ledge on the backside of the rocker pad on a stock rocker. If the lift is so high as to extend past the pad the rocker would bind. I can see the potential for some wear on the tip of the valve stem but lock up seems excessive. I'd be more concerned about fast ramp cams, too soft springs and valve float being a larger issue.
Kenny said the stock rockers go over the arc they were designed for when you go over .600 lift. When the rocker does this they will tend to lock up. Meaning they will hang when the valve is full open. Almost like when you don't have enough spring pressure and the lifter leaves the closing side of the cam lobe at high rpm.
Ok, so what part of the rocker did he say was locking up?
If it's the tip you are talking about, i think the lift # you are thinking is of is .630. At least with the stock powdered metal guides. Even then, if you are over .550 you are operating over the valve lift intended with the stock rocker arm. The curve of the tip is only designed to remain centered on the valve lift until around .550, after that is scrubs across the top of the valve stem. SOOO many folks run above that lift and don't have short term issues--i am sure they need valve guides a lot quicker than usual, but their rockers aren't causing valve float and the valve lift isn't causing their trunnions to wear out quickly.
I don't know about the effect on trunnion wear, but like many have already said in this thread, it does affect valve guides from side loading, the tip of the stem, and probably the rocker arm tip. There are examples of stock rockers being ran at lifts over .630. Not the greatest idea, granted, because the higher the lift you go the more side loading and improper geometry you have, but i don't think anything is mechanically "locking up." Unless the guides are so worn the valves hang up somehow from that...
I do agree that roller rockers are a better option for higher lifts, though, since they don't have this issue. They are inherently heavier over the tip and require more spring pressure for control, though. If it's one advantage stock rocker arms have, it's weight over the tip.
But i doubt there is much of a connection between trunnion wear and the rocker arm scrubbing across the valve tip.
Last edited by dreadpirateroberts; Dec 27, 2019 at 07:27 PM.
Been meaning to look at mine since the engine is apart. these are Comp's. I used Tooley's in another engine, I wonder if they are also Comp? Dunno.
Maybe 2k miles, 150 or so passes.
Just starting to fail. So won't be going back in. Obvious they just used poor material and didn't harden them good enough. Pretty frustrating.
Back to the drawing board I guess.
BTR 660 spring kit.
Tooley has some nice looking upgraded kits, but are out of stock of course....
But, Amazon to the rescue.
Ron
Last edited by RonSSNova; Dec 27, 2019 at 11:29 PM.
Been meaning to look at mine since the engine is apart. these are Comp's. I used Tooley's in another engine, I wonder if they are also Comp? Dunno.
Maybe 2k miles, 150 or so passes.
Just starting to fail. So won't be going back in. Obvious they just used poor material and didn't harden them good enough. Pretty frustrating.
Back to the drawing board I guess.
BTR 660 spring kit.
Tooley has some nice looking upgraded kits, but are out of stock of course....
But, Amazon to the rescue.
Ron
BTR uses comp trunion upgrade on their V1 original. BTR has a V2 that has an inner race for the bearings like the oem but are caged so the bearings don't come out. RPM speed at the ws6store has the max effort rockers with a captured bearings with an inner race also.
Ok, so what part of the rocker did he say was locking up?
If it's the tip you are talking about, i think the lift # you are thinking is of is .630. At least with the stock powdered metal guides. Even then, if you are over .550 you are operating over the valve lift intended with the stock rocker arm. The curve of the tip is only designed to remain centered on the valve lift until around .550, after that is scrubs across the top of the valve stem. SOOO many folks run above that lift and don't have short term issues--i am sure they need valve guides a lot quicker than usual, but their rockers aren't causing valve float and the valve lift isn't causing their trunnions to wear out quickly.
I don't know about the effect on trunnion wear, but like many have already said in this thread, it does affect valve guides from side loading, the tip of the stem, and probably the rocker arm tip. There are examples of stock rockers being ran at lifts over .630. Not the greatest idea, granted, because the higher the lift you go the more side loading and improper geometry you have, but i don't think anything is mechanically "locking up." Unless the guides are so worn the valves hang up somehow from that...
I do agree that roller rockers are a better option for higher lifts, though, since they don't have this issue. They are inherently heavier over the tip and require more spring pressure for control, though. If it's one advantage stock rocker arms have, it's weight over the tip.
But i doubt there is much of a connection between trunnion wear and the rocker arm scrubbing across the valve tip.
Kenny said the tip if the rocker over the valve locks up. It does sound extreme, but we are talking nano seconds considering the speed of the valve train at high rpm.
BTR uses comp trunion upgrade on their V1 original. BTR has a V2 that has an inner race for the bearings like the oem but are caged so the bearings don't come out. RPM speed at the ws6store has the max effort rockers with a captured bearings with an inner race also.
Not trying to derail from the original posting. but I'm glad I've read this thread. I've got this Comp trunnion upgrade kit that I purchased from someone. Doesn't look like I'll be using it after reading all the issues with all the trunnion wear. The box is dated 08/14/17.
Could the wear be attributed to and or because of ZZDP(Zinc & Phosphate) wasn't added to the engine oil?
The original GM rockers I have are used but from a working LS3 engine, maybe I'll just leave them alone? Camshaft I'm going to be using has .568" lift.
Keep in mind I'm an original SBC guy that's going to be using LS platform on my swap, so be nice.
Opinions?
The issue was with Comp trunnions themselves, due to bad metallurgy that caused premature wear and flaking of the surface metal.
EXACTLY!
I bought mine in 2014. I just don't street drive the car all that much.
The real question is, did they correct the issue? I've never read anything to that effect.
I think they should replace them for free.
If your used rockers are in good shape, ie good pushrod cups (I've seen failures there) and the tip isn't worn where it contacts the valve stem, I'd use them no issue.
I bought mine in 2014. I just don't street drive the car all that much.
The real question is, did they correct the issue? I've never read anything to that effect.
I think they should replace them for free.
If your used rockers are in good shape, ie good pushrod cups (I've seen failures there) and the tip isn't worn where it contacts the valve stem, I'd use them no issue.
Ron
Good question! My only thing here is, "once BURNED, twice shy!".
I went with the Straub bushings and started seeing bronze in the oil but I'm not so sure it was from the rocker arms. Some guy I let do some work on my TSP heads swapped my valves and jacked my heads all up and wore out some of the guides prematurely. I've since went to Brodix BR7s and T&D pedestal mount rocker arms.
I went with the Straub bushings and started seeing bronze in the oil but I'm not so sure it was from the rocker arms. Some guy I let do some work on my TSP heads swapped my valves and jacked my heads all up and wore out some of the guides prematurely. I've since went to Brodix BR7s and T&D pedestal mount rocker arms.
I have the Straubs and saw bronze the first couple oil changes but then it dropped significantly once they wore in. It was also a fresh rebuild so expected to see stuff in the oil on break in.
I went with the Straub bushings and started seeing bronze in the oil but I'm not so sure it was from the rocker arms. Some guy I let do some work on my TSP heads swapped my valves and jacked my heads all up and wore out some of the guides prematurely. I've since went to Brodix BR7s and T&D pedestal mount rocker arms.
Not sure you can blame the needle bearings seeing that factory rockers roll on needle bearings for 100K or more without major issues.
Kenny said the stock rockers go over the arc they were designed for when you go over .600 lift. When the rocker does this they will tend to lock up. Meaning they will hang when the valve is full open. Almost like when you don't have enough spring pressure and the lifter leaves the closing side of the cam lobe at high rpm.
If that were true youd definitely see that on any dyno graph and more valves would get bent, completely wiped out, or ported pistons because nearly every more aggressive aftermarket cam and basically any ls3 cam would do that.
The theory there doesnt pan out. Especially with how many cylinder heads ive personally and professionally seen and disassembled with nearly every cam you can imagine.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
