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Bronze Trunnion Bushings - Inspect Them Just Like Springs
PSA for something that I’m not sure we all keep in mind when checking springs every 20k or so…
I purchased my 13 1LE used with around 80k miles. It had Kooks, rotofab, BTR stage 4 cam and .660 springs, and unknown brand of bronze trunnions. I want to reiterate that I do not know what brand the trunnions are. This setup had approximately 40-50k miles on it along with a lot of street abuse from the previous owner, as well as several track days by me (20 minute sessions at WOT aren’t easy on anything), but shifts were low 6500 or so. This setup made 450 on a Mustang dyno.
After my last track day I started to get random misfire codes. I changed plugs and wires, but that was no help. Moved coil packs around, but the misfires would just hop all over the place. Finally in the fall I took the car for a quick ride with my daughter up the street when I heard some not good sounds Upon tear down, #7 piston was cracked, rod bent, as were the valves and guides. Assumption was detonation (it was #7, of course!). Before the incident, oil (M1) was sent to Blackstone who detected excessive amounts of bronze…
When rebuilding, I planned on reusing the bronze bushings as the rockers seemed tight. It wasn’t until I was trying to set preload and measure for pushrods that things became peculiar. When trying to tighten the rockers, they’d get tight, but torquing would result in a sort of “pop” and getting loose. This was consistent across most of them, so I pulled it apart and popped the bushings out. I was very shocked at how worn they were, especially since they felt nice and tight. Oil had been pushing through them for some time, but some were very ovaled - including #7. This explains all of the misfires (the trunnion shaft hopping around), and ultimately the shaft getting enough space to push up on the valve more than pushing in on the pushrods and compressing the lifters. Had I paid attention to that oil analysis, I would have immediately pulled those trunions - it was a very expensive oversight on my part.
My new build now includes the BTR shaft mount rocker kit with needle bearings. While I’ll personally never use the bronze bushings again, the miles mine had, along with the abuse they took, it’s no wonder they ended up like they did. Like springs, though, we all need to inspect our trunions. As cheap as they are, just replace them every 20k miles or so like springs - solid bushings or needle bearings.
Good stuff! Definitely need to be inspecting and replacing bushed trunnions as needed. Here were mine after 20k. Also, here's a link to a little more of the top end after 50k, 20k cammed, heads never been off the motor.
Thank you for this post.. People told me I had improperly installed mine when this happened to me at less than 15K miles.. I have the Elgin E1839P (the one just under the SLOPPY STAGE 2) so the lift and duration are nothing crazy. I only used the bushings because I thought they were an upgrade to the factory stuff. Boy was I WRONG. After finding all 16 of mine DESTROYED-they looked just like acammers above.. The difference is I NEVER took this truck to the track. It was, and still is, my daily driver. I changed the oil religiously and I'll bet the engine never saw 6500RPM in the short time the bushings were in the motor. At the time I found this failure I posted on this web site about it and everyone said it was my fault because I did not install them correctly... Love how time sheds new light on stuff like this. I switched back to a set of Summit factory rockers with the updated trunion bearings already installed and have not had a single issue in 20K miles since then. Maybe I got the "bad" set out of the bunch. Knowing my luck that is possible. But as more of these stories come out... It makes you wonder if more people have the issue but they just have not inspected them to find it. My situation was random misfires, and a HELL of a lot of valve train noise that no amount of push rod length swapping would fix. Then I took one rocker apart and about had a stroke at what I saw had happened to the inner diameter of the bushing. It's funny how other manufacturers have used bushings inside engines for YEARS with no issues. Look at GM Gen IV rods that are bushed, and they don't seem to have issues... and yet.... these rocker bushings....hmmmm... I'll just leave it at that.
Interesting - I figured I couldn’t be the first one. I’d imagine a lot of people have this issue and just don’t know it. Mine was likely a combination of the miles and the type of driving I was doing. Like you, though, I wasn’t spinning it very high. And yes, everyone swapped to bronze bushings because it was the “upgrade” due to the incessant fear the stock needle bearings were going to fly apart. Who knew this is where we’d end up with the benefit of hindsight.
Checked/ left alone on my old 4.8 ly2 procharged truck at 35k mi and they felt great no issues at all right before I sold the truck. But it could have been my very mild GM ls1 hotcam and ls6 springs that really saved it from a beating.... I'm thinking more radical cam profile ( hot cam was like 218/ 228 .525/.525 lift worked fine in a blown 4.8) vs a big duration/much higher lift and valve spring Pressure much higher would definitely reduce the service life of a bronze bushing... Just my thoughts any way.
That’s part of the issue, though: they feel fine. The only way to know for sure is to pop them out of the rocker. Mine felt tight, but do they look alright to anyone?
While I’ve heard stories about bronze bushings going bad, I’ve never heard anything bad about CHE bushings. Hopefully they came up with a good alloy. I wonder if CHEs full floating design has helped it live longer
THis makes BTR shaft rockers look worth investigating more.
Thank you for this post, just something else i have to keep a eye on now. SMFH. To answer your question above. No, some looked egg shaped to me on the I.D. (Internal Dimension) unless its just the picture angle's.
While I’ve heard stories about bronze bushings going bad, I’ve never heard anything bad about CHE bushings. Hopefully they came up with a good alloy. I wonder if CHEs full floating design has helped it live longer
THis makes BTR shaft rockers look worth investigating more.
Agreed, many people gloss over the CHE kit because of the price and possibly believe that all bushing upgrade kits are the same.
I only use the CHE trunnion upgrade. I've installed numerous CHE kits and will be inspecting a set on my personal build. The full floating design may be the key for the bushing trunnion upgrade.
Also not a fan of caged needle bearings riding directly on the trunnion as well.
And then there's the numerous cases of people having no issues with the stock trunnion setup.
I wonder if cam lift plays a role. Some of the cams are now pushing .530 lift on LS1's and that could possibly cause some rocker tip issues. LS3's are running even more lift IIRC.
I wonder if cam lift plays a role. Some of the cams are now pushing .530 lift on LS1's and that could possibly cause some rocker tip issues. LS3's are running even more lift IIRC.
I run a .620 lift Cam Motion cam with BTR 660 lift springs. I'm using stock LS3 rocker arms. Several months ago, I replaced springs and rocker arms after over 30K miles. The old stuff looked perfect. I trust the stock stuff more than the aftermarket. Not saying I would use stockers with a higher lift cam with aggressive ramp rates though. I think they fit my program just fine. And I routinely buzz it to 7K.
While I’ve heard stories about bronze bushings going bad, I’ve never heard anything bad about CHE bushings. Hopefully they came up with a good alloy. I wonder if CHEs full floating design has helped it live longer
THis makes BTR shaft rockers look worth investigating more.
The issue with pressed in bronze bushings is only a small arc gets all the load. Over time this causes wear.
With the full floating style from CHE they rotate freely and walk around so the load is spread over the entire 360. To prove this when you install them put a jiffy marker dot on the CHE bronze bushing along it's flanged edge at the top. Do this to them all. Take a look after 5000 miles and you will see that have all walked around and now at different positions; and continue to do so as the engine runs.
Last edited by v8monstermiata; 07-24-2022 at 06:04 AM.
04-29-2022, 09:22 AM
Bronze Trunnion Bushings - Inspect Them Just Like Springs 
Upon tear down, #7 piston was cracked, rod bent, as were the valves and guides. Assumption was detonation (it was #7, of course!). Before the incident, oil (M1) was sent to Blackstone who detected excessive amounts of bronze…
