[Baddawg53]

I have an SS, large cam (.640) installed with the LS7 lifters/springs. I've read all about the potential issues with the LS7 lifters etc, and plan to replace them with Johnson's. Basically rebuilding the whole top end.

I've got about 7k miles on the car since the cam install, and I've started tracking it. Obviously this is a little harder on the engine as it's constant full throttle and 6k+ rpm pulls.

Looking for recommendations on how soon I should think about tearing the engine apart again to do some preventative maintenance on the valve train. Any suggestions are welcome.

[SSDan]

I'd suggest starting with a baseline oil analysis from a lab such as Blackstone. That will tell you what and how much metal wear there is in the oil. A big lift cam and a lot of high rpm use equals short life span for the lifters and cam lobes. For reference I had a total cam lobe and lifter failure on an LS3 at 17k miles with a cam with slightly less lift than yours. I did not stay on top of the valvetrain wear and it bit me in the butt with a big valvetrain failure and expensive repair.

[KingLT1]

Usually the valve springs are the first component with a high lift cam to weaken. I would be checking them every 10-12k miles. The cam lobe intensity also plays a big role on how hard the lifter takes a beating as well. You could have a high lift, mild lobe cam that can potentially live a long life setup correctly with LS7 lifters. Where as you could have low lift aggressive lobe cam that beats the snot out of the lifters in less then 10k miles. The entire valve train as a whole needs to be properly put together. Where guys run into trouble is mixing different parts together that have not been tested together.

I like Johnson 2110 lifters because they simply will flat out work in almost any combination short of a solid roller setup. They are excellent at resisting pump up at higher rpm and the results are the valve getting the full lift from the cam lobe. To me it's not worth saving 200.00 on lifters when going through all the effort it takes to swap cams on these engines. Just put the Johnsons in and sleep well at night.

[L78toLT1]

OP, do you have upgraded rocker trunions? All LT motor gurus seem to recommend them. I've been running the comp cams needle bearing trunking but am a little nervous about them as the bronze bushing variety seems to have replaced the needle bearing type. What we really need for these motors is a robust roller tip rocker. TSP lists some on their website but they never seem to be in stock.

[parish8]

I broke an exhaust valve last year after about 3000 very hard miles. I suspect it was due to a lack of valve control. Stock non dod lifters, decent springs but not shimmed to the proper height and running right up to valve float rpm over and over. I was told by one person that the Texas speed lobes are pretty aggressive and tend to bounce the valve, no idea if this is true.

No help for your original question.

[Baddawg53]

Thanks for all that input. I'll have to dig up the cam card and get the specs, figure out just how aggressive it is. I do wish I woulda installed the johnson's originally.

I upgraded the rocker trunions when doing the cam, needle bearings. I looked for a whole rocker but couldn't find one at the time.

I like the idea of an oil sample until I figure out when I want to pull the heads off again. I'll definitely do that next oil change as I just did that.

I was thinking next fall/winter would be a safe time frame, but the abuse it's getting on track has me contemplating doing it sooner.

[Baddawg53]

Originally Posted by KingLT1

Usually the valve springs are the first component with a high lift cam to weaken. I would be checking them every 10-12k miles. The cam lobe intensity also plays a big role on how hard the lifter takes a beating as well. You could have a high lift, mild lobe cam that can potentially live a long life setup correctly with LS7 lifters. Where as you could have low lift aggressive lobe cam that beats the snot out of the lifters in less then 10k miles. The entire valve train as a whole needs to be properly put together. Where guys run into trouble is mixing different parts together that have not been tested together.

I like Johnson 2110 lifters because they simply will flat out work in almost any combination short of a solid roller setup. They are excellent at resisting pump up at higher rpm and the results are the valve getting the full lift from the cam lobe. To me it's not worth saving 200.00 on lifters when going through all the effort it takes to swap cams on these engines. Just put the Johnsons in and sleep well at night.

Do you have a specific spring that you'd recommend? As I said I currently have LS7 springs and lifters.

[KingLT1]

Originally Posted by Baddawg53

Do you have a specific spring that you'd recommend? As I said I currently have LS7 springs and lifters.

BTR dual .660 lift spring kit.

[Baddawg53]

Originally Posted by KingLT1

BTR dual .660 lift spring kit.

Thanks!!

[cmitchell17]

I don't see where you could tell much from an oil analysis? What specific metals would you be looking for? Is there a way you could look for valve spring failure? As far as I know the valve springs fail by fatigue and not be wear so I don't know how you would detect that?

What specific metals would you see in a early lifter failure?

A stethoscope seems like the more reliable tool and being able to detect a change in sound.

The way people talk about how aggressive some of these shops lobes are along with how many personal stories they have of failures, you would think your motor is about the blow up any second.

You rarely hear talk of how high of a RPM you can push these motors too, I hear rod bolts are the limit, but then I don't know if that comes from someone just saying that or evidence or what.

I run mine at a 7275 rpm extreme cutoff, this allows me to shift at 6950 rpms and have enough room to not bounce off the rev limiter when the tires spin. I initially had it at 7200, but I had to bump it up to not hit the rev limiter when spinning. I came to the 7200 conclusion not from any evidence or analysis or testing but just guessing. I realize there's no RPM limit where its going to blow up or not, but if you look at the GMPP 535 LT1 hot cam crate engine, the extreme rev limit is at 7100, and the LT1 im pretty sure has stock valve springs, I think LS7 lifters?, and stock everything else I think? So I figured I was still safe at 7275.

[Baddawg53]

I know you're right about the fatigue failures, and especially with the springs. However I like the idea of the oil sample because it'll tell you if something is starting to wear prematurely. Whether it's bearings or whatever. If you get a test back with a high level of whatever metal you can maybe prevent a total failure. I guess it's more of an overall engine health deal moreso than a specific part.

My engine is still running perfectly, I tend to shift it from 6600-6800, and it spends a lot of time at 4500+. Peace of mind is pretty much what I'm after here.

[cmitchell17]

Originally Posted by Baddawg53

I know you're right about the fatigue failures, and especially with the springs. However I like the idea of the oil sample because it'll tell you if something is starting to wear prematurely. Whether it's bearings or whatever. If you get a test back with a high level of whatever metal you can maybe prevent a total failure. I guess it's more of an overall engine health deal moreso than a specific part.

My engine is still running perfectly, I tend to shift it from 6600-6800, and it spends a lot of time at 4500+. Peace of mind is pretty much what I'm after here.

Yeah I am with you, I have been doing analysis on mine every oil change almost, I think, but usually every time the total base number indicates I can run it longer.



The 2/2/2020 is when I put in my cam but it only had about probably a few hundred miles on that sample before I changed it with the cam in, but you can tell wear metals were significantly elevated on the next 2 samples on 3/27 and 9/12. I am probably well overdue by now for another change. Iron is defiantely way up and I would suspect due to cam and lifter roller wear, not sure where the extra chromium comes from, and also why aluminum is elevated, I think aluminum is only used on the piston.

[Baddawg53]

That's some really great data. You can watch the progression of wear. I kinda wish I had started that before my cam install. I'm sitting just below 40k miles right now, definitely gonna do that my next oil change.

[cmitchell17]

Originally Posted by Baddawg53

That's some really great data. You can watch the progression of wear. I kinda wish I had started that before my cam install. I'm sitting just below 40k miles right now, definitely gonna do that my next oil change.

Thanks, notice how starting on the 3/27 when I put my cam in how iron jumped up to 55, kind of gives you somewhat of an idea how there was 3 times more wear with the high lift cam. Mine is a custom TSP 228/236 114 .635/.635, PAC dual springs, Johnson 2110's, TSP supposedly "hardened" pushrods, and the PAC integrated spring seats/seal and the PAC titanium retainers.

After hearing of all the failures and horror stories, I really wish I would have gone with a .600 lift cam instead of the "usual" .635 and wish I would have gone with a cam motion cam instead of TSP. TSP hasn't seemed like they care all that much, most of the time their answers weren't very detailed when I asked them questions. When I installed it I think my pushrods were just a little short, I could only get about 1.5 turns on the rocker arm bolt after taking up the lash. I asked them about it and they said "oh you'll probably be fine" and didn't seem concerned about it at all

I still don't know of any valve spring failure warnings or indicators?? Maybe someone else has some ideas?