LS2 Comp cams 15956 Lifter Failure
LS2 Comp cams 15956 Lifter Failure 
I had a Comp Cams 15956 short travel lifter fail at 1500 miles on a newly rebuilt LS2.
I have not finished the engine dis-assembly yet but want to know if anyone else had a similar failure. So far I've only pulled the intake and valley cover and can see the failed lifter.
At this point I don't know if it is assembly, clearance or supplier quality issue.
Here are the engine specs below if anyone would like to review.
Thoughts? Has anyone else had a failure with these lifters?
Cam
3731R/3734R 110CL straight up (CC #33730)
CNC 215 Trick Flow heads, stock Trick Flow valves
Springs:
Comp cams 921 Spring kit
Pushrods: 5/16" 0.080 wall trick flo pushrods 7.55 intake and 7.6 length exhaust. No shims under stands
Lifters: 15956-16 Comp Cams
Jesel Y2K rockers 5/16-24 adjusters.
7k rpm rev limiter
The car is street driven. 1500 miles on engine: no drag passes, less than 1 hour at road course track day, the rest street miles.
Last edited by Speed Demon; Oct 21, 2015 at 12:30 PM.
I had a Comp Cams 15956 short travel lifter fail at 1500 miles on a newly rebuilt LS2.
I have not finished the engine dis-assembly yet but want to know if anyone else had a similar failure. So far I've only pulled the intake and valley cover and can see the failed lifter.
At this point I don't know if it is assembly, clearance or supplier quality issue.
Here are the engine specs below if anyone would like to review.
Thoughts? Has anyone else had a failure with these lifters?
Cam
3731R/3734R 110CL straight up (CC #33730)
CNC 215 Trick Flow heads, stock Trick Flow valves
Springs:
Comp cams 921 Spring kit
Pushrods: 5/16" 0.080 wall trick flo pushrods 7.55 intake and 7.6 length exhaust. No shims under stands
Lifters: 15956-16 Comp Cams
Jesel Y2K rockers 5/16-24 adjusters.
7k rpm rev limiter
The car is street driven. 1500 miles on engine: no drag passes, less than 1 hour at road course track day, the rest street miles.
I guarantee you had loft, and with loft the lifters take a beating.
We've had zero issues with those lifters, but we use soft lobes, sufficient spring pressure (what's required is a LOT higher than you would think) lighter stock rockers, etc.
XE-R lobes, weak springs, heavy valves, HEAVY rockers...
I guarantee you had loft, and with loft the lifters take a beating.
We've had zero issues with those lifters, but we use soft lobes, sufficient spring pressure (what's required is a LOT higher than you would think) lighter stock rockers, etc.
I guarantee you had loft, and with loft the lifters take a beating.
We've had zero issues with those lifters, but we use soft lobes, sufficient spring pressure (what's required is a LOT higher than you would think) lighter stock rockers, etc.
Teching In
Joined: Feb 2009
Posts: 13
Likes: 0
From: Texas
Interested to hear the discussion.....what would be the suggested setup?
Brian Tooley Racing dual spring kits are close in spring rates of those used here.
Could it be the source raw material flawed (bad batch) or pushrod length/setup?
http://www.briantooleyracing.com/660...l-springs.html
The rocker arms seem to be lighter weight?
http://www.jesel.com/valvetrain/inde...ers/pro-series
Testing Katech did comparing spring setups and valve float.
http://www.corvetteforum.com/forums/...tte-forum.html
Brian Tooley Racing dual spring kits are close in spring rates of those used here.
Could it be the source raw material flawed (bad batch) or pushrod length/setup?
http://www.briantooleyracing.com/660...l-springs.html
The rocker arms seem to be lighter weight?
http://www.jesel.com/valvetrain/inde...ers/pro-series
Testing Katech did comparing spring setups and valve float.
http://www.corvetteforum.com/forums/...tte-forum.html
The rocker arms seem to be lighter weight?
http://www.jesel.com/valvetrain/inde...ers/pro-series
http://www.jesel.com/valvetrain/inde...ers/pro-series
No roller rocker made is effectively as light as a stock rocker, in terms of moment of inertia. Anytime you put a axle and roller that far away from the center of rotation, the MOI increases significantly. Now combine that increased weight with a pushrod adjuster cup and the MOI increases again.
NASCAR Cup and Pro Stock don't use adjuster cups and they NEED the adjustability.
Teching In
Joined: Dec 2007
Posts: 27
Likes: 0
From: Plainfield, IL
The last time I tested 921 springs they were 20 lbs seat and 40 lbs open less pressure than our Platinum springs. In the spintron testing that I've been involved in, that's a huge difference. We had a Patriot Gold spring/roller rocker setup with a Comp XE-R cam that lofted to .700" lift using a .600" lift cam.
No roller rocker made is effectively as light as a stock rocker, in terms of moment of inertia. Anytime you put a axle and roller that far away from the center of rotation, the MOI increases significantly. Now combine that increased weight with a pushrod adjuster cup and the MOI increases again.
NASCAR Cup and Pro Stock don't use adjuster cups and they NEED the adjustability.
No roller rocker made is effectively as light as a stock rocker, in terms of moment of inertia. Anytime you put a axle and roller that far away from the center of rotation, the MOI increases significantly. Now combine that increased weight with a pushrod adjuster cup and the MOI increases again.
NASCAR Cup and Pro Stock don't use adjuster cups and they NEED the adjustability.
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Verdad Gallardo So would the Tooley Platinum springs work with my set up? That is if I ran the same cam and lifters again. The lifters are the Comp Cams short travel link bar type p/n 15956-16. I imagine they are heavier than LS7 lifters. Or if you have other recommendations on cam, lifters and springs I'd certainly like to hear that. I want to be sure when I rebuild that it lives a while longer than last time.
I'd go with a softer lobe, lighter valve, stock rockers, and thicker pushrods with a better valve spring. Those lifters are actually ok. Might be the only thing right in that combo.
I don't think you need to go changing cams. XE-R Lobes worked well for a lot of years, but are a bit out dated now. You just need to run the proper springs and make sure that your preload is correct.
You can use a multitude of springs that will fix you up.
BTR Platinums
Comp 26925 (which i believe are the same as the BTR) He will know for sure
PRC .650
PAC .660
All have spring pressures at 1.8 install height of between 130 and 140. I have used the PRC with no issues as well as the comp/btr. Im not sure if your seats and retainers will swap from your 921's but they are interchangeable on all the other springs I listed.
You can use a multitude of springs that will fix you up.
BTR Platinums
Comp 26925 (which i believe are the same as the BTR) He will know for sure
PRC .650
PAC .660
All have spring pressures at 1.8 install height of between 130 and 140. I have used the PRC with no issues as well as the comp/btr. Im not sure if your seats and retainers will swap from your 921's but they are interchangeable on all the other springs I listed.
PAC 1905 would be another choice.
That's assuming the stock rockers for any of those.
If you keep the Jesels, you need to up the spring to 1208X from PAC shimmed up for more seat pressure and more open pressure to control the rocker.
That's assuming the stock rockers for any of those.
If you keep the Jesels, you need to up the spring to 1208X from PAC shimmed up for more seat pressure and more open pressure to control the rocker.
That 1208x has a pretty healthy amount of spring pressure!
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Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com