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My winters list of modifications to my 2006 Corvette did not include a new CAM until I discovered the damage illustrated by the attached photo. My winter project was to include new PRC Heads, Johnson linked lifters. After removing the oem 243 heads and lifters, I moved on to inspect the CAM through the lifter holes and discovered damage to the intake lobe of cylinder #7. No visible damage to any of the other lobes or lifters, just the spalling of intake lobe of #7. The #7 intake lifter was perfect in every way as was all other lifters. The car finished the racing season, a test and tune session at Bandimere Speedway on October 24, 2021, with 6 passes at 10.9 seconds, 126 mph. No signs of any problems or issues whatsoever. Had I not decided to replace the heads, I most certainly would have been in trouble this next racing season. Looks like the #7 lifter turned sideways at some point but not sure how that could be as the lifter tray, and lifter looked as good as new with no damage upon very close inspection. Anyone ever seen anything like this before?
My 06 Corvette convertible has 32,000 miles and I have owned it from new in 2006. I have a hard top that allows me to run in the 10's without a cage. The damaged CAM is the original oem stock cam (204/213/116), never changed or otherwise touched in any way. I installed a 1503 Edelbrock E-Force Supercharger in 2010 with Crane 1'8 Quick Lift Roller Rockers with duel beehive springs (Kit offered by Vinci Performance in 2010). I went E85/Flex fuel last year (2021) and maxed out the boost by adding the 2.75 inch pulley. It was a real chore tuning the engine and transmission to a point where they worked well together. As I mentioned, never witnessed any performance issues or problems that pushed me to inspecting the CAM, just do diligence once the heads and lifters were removed for the new configuration.
Original Lifter Trays and Lifters with no signs of wear or damage of any kind - they look as new as my expensive Johnsons.
Original CAM - never been touched.
Duel Springs with 1.8 Quick Lift roller rockers since 2010 (approximately 10K miles).
The lifter tray is the only thing that is holding the lifter from rotating since they are not pair linked,and with more lift from the cam, makes the problem even worse.
So just like springs with a high lift cam that you need to change every 30K/when the cam is first installed, so the same with the lifter trays as well (or go to pair linked lifters, so your not worrying about lifter trays that can wear out and allow the lifter to rotate in the tray instead.
And how we can tell its a lifter that rotated for the roller to be off line with the cam lobe line, the roller was sideways'ish on the cam lob, since notice how the groove mark is less the width of a lifter roller instead.
And to note, better to increase the rocker ratio, than to increase the amount that the lifter is being lifted the cam lob.
You still get the same amount of valve lift if done correctly, but it being done at the rocker, instead of the increase travel of the lifter in the tray instead.
The lifter tray is the only thing that is holding the lifter from rotating since they are not pair linked,and with more lift from the cam, makes the problem even worse.
So just like springs with a high lift cam that you need to change every 30K/when the cam is first installed, so the same with the lifter trays as well (or go to pair linked lifters, so your not worrying about lifter trays that can wear out and allow the lifter to rotate in the tray instead.
And how we can tell its a lifter that rotated for the roller to be off line with the cam lobe line, the roller was sideways'ish on the cam lob, since notice how the groove mark is less the width of a lifter roller instead.
And to note, better to increase the rocker ratio, than to increase the amount that the lifter is being lifted the cam lob.
You still get the same amount of valve lift if done correctly, but it being done at the rocker, instead of the increase travel of the lifter in the tray instead.
I also noticed the narrow line of contact. Not certain if rotating lifters are the cause, or not. I once had a cam lobe that had a lifter moving around on it due to one bad set of flats in the tray, which allowed the lifter to kind of flutter back and forth. Definitely left some funny looking marks on the lobe that you couldn't feel or catch with a fingernail. You can see most all of the lobes on the OPs cam have that narrow line "witness mark." But only one lobe is bad. I'm leaning towards it being a bad cam that has some insufficient heat treating, and/or low grade steel, or bad iron in the core.......
The CAM pictured is the original OEM LS2 CAM (204/213/116) that was manufactured by GM for the LS2 in year 2006 or available in the 2006 Corvette. The pictured damage is on the back-side of the cam lobe, or as the intake valve is closing. The lifter tray for this lifter and cam lobe is identical in every way to all other lifters and how they seat and travel throughout the limits of the lifter tray. The damage is noticeable to the touch and appears to be associated with the lifter somehow twisting in the lifter tray but I have been unable to twist or otherwise change the orientation of the lifter in the tray by force, twisting, etc. to see if it is possible to forcibly change its orientation. I am baffled but happy that I found this damage. I have linked lifters now so not worried going forward of this happening again. As mentioned is earlier posts, this could be associated with a material flaw but the damaged area is so perfect in its relationship to the lifter.
The CAM pictured is the original OEM LS2 CAM (204/213/116) that was manufactured by GM for the LS2 in year 2006 or available in the 2006 Corvette. The pictured damage is on the back-side of the cam lobe, or as the intake valve is closing. The lifter tray for this lifter and cam lobe is identical in every way to all other lifters and how they seat and travel throughout the limits of the lifter tray. The damage is noticeable to the touch and appears to be associated with the lifter somehow twisting in the lifter tray but I have been unable to twist or otherwise change the orientation of the lifter in the tray by force, twisting, etc. to see if it is possible to forcibly change its orientation. I am baffled but happy that I found this damage. I have linked lifters now so not worried going forward of this happening again. As mentioned is earlier posts, this could be associated with a material flaw but the damaged area is so perfect in its relationship to the lifter.
If that's the case, the cam took a dump. Known problem with some GM cams in that time period. If you search, you'll see what I mean. Worst part isn't needing a new cam. Worst part is what did all that powdered steel do to the rest of the engine, like scored cylinders, pistons, and rings, oil pump trashed, etc. You might get away with new cam, lifters, and trays. You won't know until checking with a borescope, pulling the cam, heads, lifters, and trays. I hope you'll consider an aftermarket cam. You don't have to go crazy with the specs. If you're happy with its performance stock, just get a similar grind, and start over with the motor. I'd get a new oil pump, Timing Chain and gears, lifters, lifter trays, etc. One thing I'd buy for sure is a rare earth drain plug for the sump. It can grab a lot of junk floating around in your oil when something like this happens, minimizing the collateral damage, at least somewhat. Best of luck to you, my friend.......
Normally, when there is cam damage its from either a bad lifter or one that started spinning in the lifter bore. And it usually manifests as a groove on the cam at the highest point on the cam lobe. Your cam has damage on the side of the lobe and the top of the lobe looks okay. Just plain weird. So again, I am thinking defective cam.
The metal missing from the Intake lobe most certainly found its way through the engine. However, I did a thorough inspection of the pistons, cylinders, timing chain, etc. when tearing the motor down for new heads, valves, springs, cam, lifters, push rods, rockers and water pump. I have a magnetic oil drain plug which only revealed graphite type residue attached to the magnet on the plug. Compression tests before and after tear down revealed an increase of 5lbs in compression across all cylinders. I tested compression before the tear down and after placement of the new cam, heads, etc. Everything looks balanced and appropriate for the new configuration. I have not yet started the car as I am waiting on a few more parts (Ice tank for supercharger intercooler). I hope to have everything done by mid April and perform first start and go from there. The amount of material missing from the intake lobe is quite minimal but any amount is not good. I believe I caught this just in time before catastrophic damage could occur.
To me the missing piece is wider than the wear pattern of other lobes (the dark marks seem wider than the damage at that position)
I don't like mixing OEM valvetrain parts with heavy springs and high rpm engines. If this wasn't simply a defect and if it has anything at all to do with parts choice it was the strong springs and possibly related to the RPM and oil supply conditions. Or it was incited by debris- oil analysis recommended, check the other lobes and journals for embedded trash that you can catch a fingernail on and so forth.
Got a photo of the corresponding lifter roller as well?
I would imagine the lifter wheel would show damage, but I'm certain the cam would be the cause. But you never know, which is the worst part. I've been running LS7 (supposedly!) lifters, with a Futral cam on springs with 170lbs seat, 430lbs open, and have been for almost 8 years/30,000+ miles, with no issues......yet. I also know I'm close to the max they'll handle, and probably over the the max safe design. So, I've maybe been lucky, and probably wouldn't recommend the LS7 lifters be run on a combo like mine. But-My point is I really doubt the lifter is the root cause when running a stock cam. GM had a run of bad cams then, so......
I would imagine the lifter wheel would show damage, but I'm certain the cam would be the cause. But you never know, which is the worst part. I've been running LS7 (supposedly!) lifters, with a Futral cam on springs with 170lbs seat, 430lbs open, and have been for almost 8 years/30,000+ miles, with no issues......yet. I also know I'm close to the max they'll handle, and probably over the the max safe design. So, I've maybe been lucky, and probably wouldn't recommend the LS7 lifters be run on a combo like mine. But-My point is I really doubt the lifter is the root cause when running a stock cam. GM had a run of bad cams then, so......
The damaged area of the cam lobe is precisely the width of the lifter roller (.375" wide). There is no damage to the roller whatsoever, pristine, good as new. If the lifter were to twist or otherwise change position in the lifter tray the damaged area would verry in width or depth and not perfectly match the lifter roller. I am baffled at how this damage occurred without damaging the lifter or lifter roller. There most certainly had to be a defect of some type in the cam lobe in order for this damage to occur. I have replaced everything with exception of the short block. Waiting on hose for my ice tank and will be ready for first start once the hose arrives and is installed.
The damaged area of the cam lobe is precisely the width of the lifter roller (.375" wide). There is no damage to the roller whatsoever, pristine, good as new. If the lifter were to twist or otherwise change position in the lifter tray the damaged area would verry in width or depth and not perfectly match the lifter roller. I am baffled at how this damage occurred without damaging the lifter or lifter roller. There most certainly had to be a defect of some type in the cam lobe in order for this damage to occur. I have replaced everything with exception of the short block. Waiting on hose for my ice tank and will be ready for first start once the hose arrives and is installed.
Ive heard that sometimes the cam has softer steel. Look it up i read it on here.
The damaged area of the cam lobe is precisely the width of the lifter roller (.375" wide). There is no damage to the roller whatsoever, pristine, good as new. If the lifter were to twist or otherwise change position in the lifter tray the damaged area would verry in width or depth and not perfectly match the lifter roller. I am baffled at how this damage occurred without damaging the lifter or lifter roller. There most certainly had to be a defect of some type in the cam lobe in order for this damage to occur. I have replaced everything with exception of the short block. Waiting on hose for my ice tank and will be ready for first start once the hose arrives and is installed.
As posted before, your cam was a bad core, or improper heat treating, or both. Soft lobes won't last on any cam. Worst part is all the crap thats floated around in your engine..........
I can't see how the heat treating of the cam was not done properly on just that one lobe ... If the cam was not heat treated properly, it would effect all the lobes. Heat treating is done across the whole cam (not one lobe at a time).
And if it was do to a 'bad core', there would be more damage than just that one lobe.
So, what do I think happened? .. Since you stated that the lifter that rode on that one particular lobe had no damage at all ... I'm stumped !
CAM Damage
