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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Is the engine out of the car? If not, I'd pull it, disassemble the rotating assembly, inspect the bearings and journals, flush the oil galleries........ After all that, and depending on what you find, reassemble. Probably not what you want to hear, but it's what you should do.
No the engine is not out of the car. My 1.5" PVC special tool worked as planned, and the lifter was lowered through the lifter bore and rotated onto the half-pipe and then withdrawn by the big magnet through the bore of the pipe. It is definitely a 2 person operation, and there were times when we were holding our breath, for sure. But it did go exactly per plan and on need to fish around for the lifter on the windage tray. The pan was already off for cleaning and to facilitate the installation of the new oil pump. I pulled the windage tray "for grins", but there was nothing resting on top of it; no metallic pieces at all.
To my mechanical engineering mind, the cam shows six lobes where surface failure had occurred and others which were on the way. If Lethal LLC were still in business, I am sure they would tell me that I am simply out of warranty. I see things a different way, which is that Lethal LLC did not know what they were doing when they specified, supplied, and installed the dual valve springs that were supplied with my OEM lifters and the Comp cam, which they also specified, supplied, and installed.
Thank you for your post. You saved my engine. I had sent the heads to AHP a week earlier, and after reading about Lethal Racing doing the engine mods to your engine, I was concerned .The previous owner of my Z06 had used the same shop and had a similar cam and springs setup. My engine was running good, no reason to pull the heads except for the valve issues that I keep reading about. The oil filter was inspected and seemed pretty normal, so I then pulled the lifters to inspect the cam and then noticed abnormal wear on # 2 Intake lifter roller and #3 exhaust lifter roller. The cam also had abnormal wear on #2 Intake lobe,#3 exhaust lobe and #6 Intake lobe. Thank you Z.06 for bringing this to our attention!
Thanks Michael. I like your personal experience and thanks for sharing it. I already have the pan off the engine to enable a thorough cleaning, and was surprised to find a bit of my Comp Cam in the oil pickup! It was a piece of hardened cam lobe. GD Comp Cam. From what I can see, my stuck lifter still has its roller intact. When I say stuck, the lifter will go through about all of its normal range of motion with no excessive force, only the very bottom of the lifter is mushroomed out and will not enter the bore. I'm sure this is from the pounding the roller took from the cam with part of the hardened layer spalled off.
Here is my list of new and cleaned parts:
* New camshaft and installation kit, AHP116
* New lifter set, OEM
* New valve springs, PSI 1515
* New oil pump, OEM
* New oil hoses between engine and oil sump tank
* New crankshaft damper pulley, ATI
* New ARP bolts for cam and crankshaft pulley
* New rocker assembly for the stuck lifter, OEM
* New pushrods to the length needed for the new cam and shaved heads (0.020)
* Ultrasonically cleaned engine oil cooler section of my DeWitts radiator
* Ultrasonically cleaned LPE oil sump tank (after total disassembly)
* Hand cleaned bottom pan for engine
* Hand cleaned oil pickup tube
So I have pretty much taken Mordeth's recommendation to replace everything I can afford to replace on the engine oil circuit. Of course, after the engine is running again, I will pull oil and filter changes after 500 miles and 1500 miles as well.
It's threads like these that remind me of the importance of a quality lifter and the 8620 cam core with more durable lobe surfaces. If it's good enough for a top fuel dragster, it'll likely work in your car. The 5150 cores are fine for your pickup truck, but the LS7 is serious high performance from the factory and really needs to have an asterik next to it whenever discussed!
Why the PSI 1515 springs with the 116 cam? I know it depends upon the install height of the spring (1.8" vs 1.95") but if you go with the 1515 (since it's intended for the LS7 slightly longer valves,) what retainers would you go with?
It's threads like these that remind me of the importance of a quality lifter and the 8620 cam core with more durable lobe surfaces. If it's good enough for a top fuel dragster, it'll likely work in your car. The 5150 cores are fine for your pickup truck, but the LS7 is serious high performance from the factory and really needs to have an asterik next to it whenever discussed!
Why the PSI 1515 springs with the 116 cam? I know it depends upon the install height of the spring (1.8" vs 1.95") but if you go with the 1515 (since it's intended for the LS7 slightly longer valves,) what retainers would you go with?
My build sheet from AHP clearly shows PSI 1515ML Valve Springs w/Titanium Retainers. As to whether to use the 1515 or the 1511 springs, I asked for Kohle's recommendation for my engine with his cam and heads -- and I went with his recommendation. I do not understand why obtaining Titanium valve spring retainers to fit the 1515 springs should be a big deal, so perhaps someone can explain that to me. Always willing to learn.
My build sheet from AHP clearly shows PSI 1515ML Valve Springs w/Titanium Retainers. As to whether to use the 1515 or the 1511 springs, I asked for Kohle's recommendation for my engine with his cam and heads -- and I went with his recommendation. I do not understand why obtaining Titanium valve spring retainers to fit the 1515 springs should be a big deal, so perhaps someone can explain that to me. Always willing to learn.
We stock and sell the psi ti retainers for the 1515 springs.
I think a few other vendors do as well.
https://www.americanheritageperformance.com/
Last edited by American Heritage; 09-22-2018 at 11:58 PM.
First start yesterday, put 90 miles on the car at less than 2500 rpm today. Dumped the new oil and filter and replaced with fresh. Both magnetic oil plugs looked great! Will retorque rocker bolts and top up transmission oil tomorrow. Scheduled for re-tune by Pat G on Thursday evening to account for shaved heads and different camshaft. Gotta be safe before going to the track.
The problem is that they lasted long enough to hurt the both of us as well as many other customers who thought that they knew what they were doing. Our experience should serve as notice to the other people out there with cars that had cams and valve springs replaced by Lethal Racing in Lafayette. You may be driving a time bomb.
First start yesterday, put 90 miles on the car at less than 2500 rpm today. Dumped the new oil and filter and replaced with fresh. Both magnetic oil plugs looked great! Will retorque rocker bolts and top up transmission oil tomorrow. Scheduled for re-tune by Pat G on Thursday evening to account for shaved heads and different camshaft. Gotta be safe before going to the track.
Hell yeah this LS7 was blessed with a second chance at life
First start yesterday, put 90 miles on the car at less than 2500 rpm today. Dumped the new oil and filter and replaced with fresh. Both magnetic oil plugs looked great! Will retorque rocker bolts and top up transmission oil tomorrow. Scheduled for re-tune by Pat G on Thursday evening to account for shaved heads and different camshaft. Gotta be safe before going to the track.
I am happy to hear you are back on the road, let me know how the tune works out . I will be needing a tune soon
I do not understand why obtaining Titanium valve spring retainers to fit the 1515 springs should be a big deal, so perhaps someone can explain that to me. Always willing to learn.
I will edumacate you..
Until just a few months ago, Ti retainers for PSI 1515's, the same retainers that fit the stock spring BTW, did not even exist.
The issue is every other LS platform uses a different retainer than the LS7. If you tried to use a "standard" LS retainer with those 1515 springs (or a stock LS7 spring), you'd end up with way too much preload. I belive it was BTR that originally stepped up to commission a run of LS7-style Ti retainers. Prior to this, you'd have to run the stock retainer with 1515's.
1511's can utilize the standard LS1/2/3 style retrainer.
Last edited by Dan_the_C5_Man; 10-02-2018 at 08:32 PM.
Until just a few months ago, Ti retainers for PSI 1515's, the same retainers that fit the stock spring BTW, did not even exist.
The issue is every other LS platform uses a different retainer than the LS7. If you tried to use a "standard" LS retainer with those 1515 springs (or a stock LS7 spring), you'd end up with way too much preload. I belive it was BTR that originally stepped up to commission a run of LS7-style Ti retainers. Prior to this, you'd have to run the stock retainer with 1515's.
1511's can utilize the standard LS1/2/3 style retrainer.
So it seems like the manufacturers (BTR, PSI) stepped up to meet the obvious need, and there is no need to shim the 1511 springs to make them work with the LS1/2/3 style titanium retainers in an LS7 engine. That is my understanding. Still learning and still wrenching at 68.
So it seems like the manufacturers (BTR, PSI) stepped up to meet the obvious need, and there is no need to shim the 1511 springs to make them work with the LS1/2/3 style titanium retainers in an LS7 engine. That is my understanding. Still learning and still wrenching at 68.
To clarify - PSI manufactured the 1515's for a Mopar application - they just so happen to be dimentionally compatible with stock LS7 valves and retainers.
When you use a 1511 in an LS7 application, you utilize an LS1/2/3 retianer, with some quantity of base and shims, depending on the desired preload and open position / distance to coil bind values. When using 1515's, typically shimming is not needed (but that is a generalized statement - again, you may need more closed seat pressure, etc.).
Last edited by Dan_the_C5_Man; 10-03-2018 at 03:28 AM.
With over 300 miles on the rebuild, everything seems fine. I did change the oil and filter after the first 90 miles, and my magnetic oil plugs were very clean. Pat G tuned the engine computer to work with the new parts on Kurt's stingy Mustang dyno last night and the result was 508 rwhp and 490 ft-lbs of torque. The parts that went in were all about reliability and driveability and not peak numbers.
Big thanks to Kohle and Jake at AHP. Their Stage IV AHP heads that went in were not ported, but did have the Moldstar90 guides with Ferrea F2042p hollow SS exhaust valves and the valve springs were PSI1515ML with titanium retainers. A huge thanks to Andrew Frey for all of his help wrenching on the engine, including the removal of the stuck lifter. Big thanks as well to Pat G and Kurt for setting me up with a conservative tune, so I have no concern when I whale on the throttle at H2R.
09-15-2018, 10:43 PM
Valvetrain Noise, etc
