0Brian Tooley Racing

Hello All

We recently spent a couple of days on the Spintron due to some issues that we've seen with a couple of lifter failures on LS7 engines. We found something VERY interesting that looks like it would cause lifters to fail that is LS7 specific.

If you have experienced a lifter failure with a cam kit using stock rockers, please post the cam specs and spring specs.

Thanks in advance for your time.

Brian Tooley

PeteZ06

Are you seeing this with your cam kit or other cam kits?

2StrikeHtr

Thanks in advance for sharing any info you see relevant BT !

olddragger

the trays?

Dan_the_C5_Man

Ooh, let's play "name that failure mode!".

So, with the hints given so far (related to stock rockers), here is my first guess..

"Since we know there is excessive play in the stock trunnion bearings, allowing side / rotational movement, pivoting around the mounting bolt, putting a side / rotational force on the push rod, applying this same force in a "ratcheting" action to the top of the lifter, influencing the lifter to try and spin in the bore.."

Now, not sure how this would be unique to the LS7 (ahh, unless the issue above is amplified due to the offset intakes) - so now my question is, "how many lobe / lifter wheel failures have been on the intake side?".

There..

In for more clues.

0Brian Tooley Racing

We've seen it with both, which is why we we're looking at it.

This thread is a bit preemptive without more testing to confirm our suspicions, so I wanted to gather more information about what is being seen.

Any lifter that has spun in a lifter tray, in my opinion failed first, and then spun. Once the roller wheel stops spinning due to a bearing failure, it's just a matter of time before the lifter spins in the tray. I've yet to see a lifter with a good bearing that has spun in a tray. So if you've had a lifter "spin" in a tray, then you should list your cam and springs as that is certainly a lifter failure.

Interestingly enough, swapping from a bone stock rocker to a cryo treated rocker with a aftermarket trunnion had no affect on the trace.

Nowanker

Any lifter that has spun in a lifter tray, in my opinion failed first, and then spun. Once the roller wheel stops spinning due to a bearing failure, it's just a matter of time before the lifter spins in the tray. I've yet to see a lifter with a good bearing that has spun in a tray. So if you've had a lifter "spin" in a tray, then you should list your cam and springs as that is certainly a lifter failure.

OK, I'll bite...
How do you separate out the chicken Vs. egg here?
Assume it was a good lifter that spun in the tray... would it not turn from good to crap in a very short time?

meanjoe

When you say "Stock Rockers" What exactly are you referring to? CHE rockers are still stock rockers just with the new bushing as are rockers with The BTR or Comp cam kit installed. I have 12K miles on a set of LME prepared heads with the CHE rockers and all is well. Small cam and Manley springs.
Good luck with your research.

Unreal

228/232 XER XER
PRC 650 springs

Lifter failed, around 18k. Now run a 230/246 LXL LXL with same ls7 lifters (fresh set) and same springs, zero issues.

MTPZ06

Michael_D

Looking forward to what you find. I've never been a big fan of GM lifters and generally swap them out. Don't care for the 700" wheel.

C6z06man

Subscribed since I reused my stock lifters on my K501.

0Brian Tooley Racing

If you think about it, what forces would it take to make a lifter spin in a tray? In my opinion it would take severe forces to spin the lifter in a tray, lifter trays are stout.

If the lifter has spun in the tray, and the bearings are trashed, then the bearings got thrashed before it spun in the tray.

If the outside diameter of the wheel is damaged where the lifter spun in the tray, but the bearing is good, still rolls fine and all bearings are in tact, and the ID of the wheel is good, then I'd love to see it.

I should probably have prefaced this post with listing peak RPM the engine was run to also, as things get real ugly after 7000 rpm.

I'm on a mission to learn, as none of us is as smart as all of us. I have some really good resources at my disposal, so I will keep this updated as things evolve.

0Brian Tooley Racing

Any setup using a stock rocker body, regardless of trunnion used, would be considered a stock rocker for our purposes.

olddragger

Seeing lifter wheel skip on the cam ?

Dan_the_C5_Man

Thought about that as well, but that is a challenge for any setup on any engine - I guess we will need for Brian to do more testing and reveal what is unique about the LS7 combo.

Maybe we'll find that the valve train dynamics on our motor are good to just below 7K - that works well with the stock cam as it peaks below 6500 anyway..

RamAir972003

Gt20-cam on 112 lsa 11:2 compression and stock rockers with reunion upgrade....64k Install now 85k

Turbo2L

Comp 235/247, stock LS7 lifters, and PAC .650. Lifter failed, galled a cam, and took out the motor. No abnormal issues prior. Cruising at light throttle, felt a light miss, then a hard miss, and lights out. Sucked.

Dirty Howie

I believe there are documented failures (lifter/cams) in stock LS7 motors here on the Forum. Also there are many (me included on last Z06) that used your springs with stock cam. So are you going to include these in your data aquisition ??

Do you anticipate any correlation to dropped valves/catastrophic motor failure?


DH

0Brian Tooley Racing

Which PAC springs were you using?

The LS7 valve train is pretty happy with our Platinum springs to 7000 rpm. Our Platinum springs had less bounce below 7000 rpm than some new conical springs. However above 7000 rpm things get really ugly, and things got worse with increased spring pressure also.

I feel what we saw on the Spintron may be unrelated to exhaust valve dropping. It seems to me that bounce at valve closing would be really hard on valves, especially the hollow stem variety. What we're seeing is related to what happens over the nose of the lobe which would be hard on lifters.