2012 Yukon XL Denali 6.2L Cam Swap Thread
- Thread starter Geotrash
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
OP
OP
Ah, it's still out there as a specter - it's why I "upgraded" but now am thinking maybe I should've stayed stock. Any more color as to why they failed in your case?
OP
OP
Thanks for the thought. If I have any issues with oil pressure after this knocking is resolved, I'll make sure those are sealed with a thin layer of sealant. Side note: I did replace the camshaft thrust plate with new OEM, as I understand that can be a source of pressure loss also.
The trunions are just junk, poor design. Stay stock or bronze bushing. Comp was the worst offender, BTR are a bit better metal so will last longer but eventually will wear out like below. The bronze are OK, but since they're soft, they are wearing constantly and will need replacement every 10-20k. With mild builds, there is no reason to not stay stock. If going above .600 lift, then you can think about beefing up the rocker arms or going aftermarket.
Ive used btr, straub, and che. CHE was my favorite, they just drop in and are floating, no press needed. But again, it's now another wear item you have to maintain. Stock rockers require no maintenance.
https://www.corvetteforum.com/forums/c6-tech-performance/3546465-fail-comp-cams-trunion-upgrade.html
OP
OP
Update: Since I don’t have an adjustable pushrod, I used the turns of the bolt method to measure the preload on both the intake and exhaust valves for the number one cylinder. I came up with about .087 for both. It was also possible to depress the lifters with the pushrods a bit with firm finger pressure. This doesn’t bother me though but would explain startup noise until they pressurize. What’s still haunting me is that loud rapping noise that sounded like it was coming from the #1 or #3 cylinder area when it was running. Sounded like bad news to me.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
OP
OP
Thanks again, Mike. I'll order some stock rockers to try. When I start the engine again after the diagnostic work, I'll capture a video and share here.
OP
OP
Spent a half hour on the phone with Roger tonight and he's great. I'm going to pull the rockers off the #1 & #3 cylinders and get a look at the lifter positions from above. He's also concerned that the lower oil pressure I'm experiencing since the build could be a contributing factor. I put the same color and size (measured with a caliper) O-ring into the pickup tube as I took out, and it was a nice, snug fit, but it could still be an issue. He wants me to switch to 15w-40 conventional oil for a bit to see if that lifter will pump up with more pressure. Stay tuned, friends!
OP
OP
I have good news! The thicker oil quieted everything down and it’s running quiet as a mouse. I went with Valvoline 15w-40.
There was also another problem that was confusing the issue. The A/C belt is a new stretch belt and was chirping loudly at the same frequency as the lifter taps but I couldn’t isolate it from the lifter noise until they quieted down. It was so sharp in tone that it sounded like knocking from inside the truck and standing over the engine.
My mechanics stethoscope helped me to rule out valve train and water pump noise as well. I ran it for an hour tonight and the belt is almost silent, as is the valve train. Hooray!!! Thanks for all of the advice and guidance, gents!
I’ll just have to keep an eye on that oil pressure for a while. I’ll also follow up with a lessons learned post to help anyone else who wants to embark on this job. I love the cam - makes a noticeable difference on the low end. Very little throttle needed to get good acceleration.
Also, I can’t say enough good about Roger Vinci. The man knows his stuff, and provides outstanding support. Thanks to those who recommended him - that was a key tip!
There was also another problem that was confusing the issue. The A/C belt is a new stretch belt and was chirping loudly at the same frequency as the lifter taps but I couldn’t isolate it from the lifter noise until they quieted down. It was so sharp in tone that it sounded like knocking from inside the truck and standing over the engine.
My mechanics stethoscope helped me to rule out valve train and water pump noise as well. I ran it for an hour tonight and the belt is almost silent, as is the valve train. Hooray!!! Thanks for all of the advice and guidance, gents!
I’ll just have to keep an eye on that oil pressure for a while. I’ll also follow up with a lessons learned post to help anyone else who wants to embark on this job. I love the cam - makes a noticeable difference on the low end. Very little throttle needed to get good acceleration.
Also, I can’t say enough good about Roger Vinci. The man knows his stuff, and provides outstanding support. Thanks to those who recommended him - that was a key tip!
Last edited:
Similar threads
