A lot to unpack there. Without going all the way back through everything, your valves should NOT be hanging open at high RPM. That isn't valve float. That's something else entirely. Maybe I'm missing something between what your tuner actually said and how I'm interpreting what was typed, but something isn't adding up.

Valve float is when they either bounce off the seat during closing due to insufficient seat pressure OR when the lifter loses contact with the cam lobe. If it is due to the valves bouncing off the seat, then you need to increase SEAT pressure. 170 is already a high seat pressure. With the lift on your cam, you can put 0.050" shims under your valve springs and increase seat pressure that way. If the lifter is losing contact with the lobe ("loft"), then you need more open pressure (Hold this thought, because this isn't always simple). Now, there are alternate issues that can happen when you start beefing up your springs. One is I know a guy who broke the tip off his valve stem form too much spring. But also, if you don't beef up the short side, you get other issues. One is lifter collapse. That 450 open pressure is more like 760 pounds on the lifter cup. So if you're running stock or LS7 (which are stock, don't fool yourself) lifters, you may not get away with that much spring. Now, let's say you have "Big Johnson Uber" lifters in there, the next big issue is the pushrod can flex, and then spring back when the pushrod straightens itself. This causes the valve to "pole-vault" off the cam lobe and then crash back down. Based on your build info in your OP, this is what I would suspect if there is anything valve related going on.

Your tuner is correct that to control those big heavy rockers, you need more spring, but you also need the rest of the valvetrain built to support it. You want to the valve spring to be the weakest thing in the valve train, so that it gives and nothing else gives. NOTE - I DID NOT SAY YOU WANT WEAK VALVE SPRINGS, just that you want everything else to be stronger than the springs. Now, here's from your original post:

Not sure when the YT became prostreet, but that's one key difference. The other is your pushrods. If you are going to go to even more spring than a 1209X, then your 5/16 x .080 pushrods will not be enough IMO. Talk to Manton. Get 11/32 Series 5 with .125 wall thickness. I would do that even with switching to lighter rockers over the tip.

Now, getting back to the valves actually hanging open, there are only a couple things that can make the valves literally not close. One is way too much preload on the lifter, and the other is the lifters are staying pumped up and not pumping down. Put "Uber Hellfire" springs on it, and it won't fix that problem -- if that is actually the problem. My money would be on preload between the two since isky lifters are known to be generally awesome. I actually doubt the valves are just hanging open, but rather this is something I'm not quite understanding based on a game of internet telephone.

As to switching cams, the reasons a cam swap would help (or not) would have more to do with ramp rates than with total lift. Faster ramp rates are harder to control and more likely to bounce. Your old cam may simply have had a gentler ramp rate and so it ran better.

All of the above said, I would still start the engine as it sits right now, and get a spray bottle with water and spray each primary to make sure none are dead. If you prefer get a harbor freight IR temp gun and check header primary temperatures. That's the only way to rule out a dead hole. I still maintain that I typically see all hell break loose on a dyno graph when there is valvetrain issues. Yours is quite smooth.

The PAC1209X is a fantastic spring. That's what I'm going to be running on my next cam upgrade for a .740 lift solid roller intending to shift at 8K with YT 1.8's. I truly do not think his issue is not enough spring. Or if it is, it's not the only issue.

 

I totally agree with Jake (Darth) above. Dead cylinder,s & WEAK/INADEQUATE Push rods!
Stronger springs will make that situation worse. Point of reference I used Pac 1207X Springs
for a LLSR .680" lift & 7600 RPM, 165# on the seat & 460# on the Nose with 3/8 X .120 PR.
Hang in there I think/hope you are close.

 

It sure looks like you're ready to start throwing new valvetrain parts at it with your fingers crossed. Meanwhile everyone here is saying to check for dead cylinders, which you can check without having to wait on your so called "tuner".

 

Recheck lifter preload/measure for correct pushrod length. If that checks out I'd try lighter rockers like TSP roller rockers and maybe 11/32 pushrods.

 

I agree with Darth on the 5/16, .080" wall pushrod being the weak point. If anything in your valvetrain is causing issues, those pushrods are it.

However, you need to verify that all of your cylinders are firing, first.

 

I remember getting told I was wrong a couple pages back...

The PAC1209X is a mega aggressive spring for a hydraulic roller. I would say likely too much. MORE spring is definitely not the answer unless you’re going solid roller.

I read the first post, but what is your max lift with the 1.8 rocker? Is it the .660 lift, or higher because of 1.8 ratio? I have a lot more typed out I just want to make sure it’s correct.

 

I tried going back a few pages to see what was said. For my part, not saying 1209x is the perfect spring for the setup. But I am saying it is highly unlikely it is insufficient. Hope that makes sense.

 

I found it

 

I think the 1209x is too much not insufficient. Too high of lift and too much spring load for the rest of the parts.

 

We agree

 

The PAC-1238X.......and yes; more open and seat pressure. Make sure your pushrods are up to snuff!

KW

 

Damn, a lot of information. Well said.
The yella terra pro street are the next stage up from the ultra lite pro's. They do weigh more though.
With the latest information I have, we are thinking now it may be the camshaft profile.
It was originally designed for the 1.71 ratio and we are thinking the higher ratio has messed with the ramp rates but it's only an assumption thus far.
The pushrod size you mentioned, will it fit with my heads?
Old cam was a cam motion camshaft and we know these have ultra stable lobes.
Preload was also adjusted, and camshaft hung on better but after 6500rpm it rolled over.
Before it was rolling over at 6000rpm.
After what you have written I'm starting to think it may be the pushrods flexing.
Honestly I'm almost clueless about this.
There was also talk about getting another camshaft that was designed for a higher rocker ratio.
I am quite sure this crow cam is definitely more aggressive than the cam motion I had in there previously.
Springs were also measured and there was 200lb seat pressure and 500lb open pressure at .680 lift.
I know my post is stating random points in no order so bear with me.
I'm so confused about all this.

 

I thought this was a cammotion grind.

Throw a set of stock 1.7 rockers on and you likely won’t have to change a thing. Get a set with the bushed trunions.

You’ll be in the safe zone under .650 lift with 1.7 ratio.

Stock rockers are being used over 8000 rpm and loved for their light weight.

200 pounds seat pressure is too much for a hydraulic lifter. Changing the rockers to stock I’d step way back on spring. Get a good .650 lift dual spring and call it a day. 140ish seat, 400-450ish open. Even better, try the comp conicals for the latest and greatest.

 

You already have the springs and rockers. Why not llsr and lifters ? Darth could do you a horse **** cam and watch the power carry with those mid runners

 

You have some good points here.
Most likely we will try the stronger pushrods first and see how we go.
I can't use stock rocker because I have larger 10mm threads in my heads.
I will need to go back to yella terra in the standard ratio with the 10mm threads

 

I hoped it didn't come off too "lecturey" (Hey if bigly can be a word so can lecturey). I could sort of tell there was a disconnect.
It is an easy enough thing if you have the 1.7's in your possession to rule that out. Very likely the higher ratio is not helping anything
Assuming you still have the stock LS3 heads, yes I think that they will clear. One thing you will see is there is also a 5/16 x .105 pushrod. That will be about 20-25% stiffer than what you have now. The 11/32 x .120 will be about 137% stiffer. Just giving you the info in advance in case you get tempted to settle.
It is very likely and is what I suspect. Now at some point it will peak and roll over anyway. Cam motion lobes are incredibly stable. For a while the really aggressive lobes were all the rage. Then Brian Tooley did some Spintron work and discovered that there was a lot more stability with softer lobes, and then backed it up making more power with gentler ramp rates. Aggressive lobes still have their place, but myself I prefer to jump to solids if I'm going to be aggressive so that I can spring the **** out of it and not worry. Valvetrain stability is king for RPM. A good rule of thumb is to make the short side heavy and the valve side light.
Random points is fine. It's information. If your springs are actually 200 seat pressure and 500 open pressure, that's flat abusive to a hydraulic valvetrain. And likely not a PAC 1209X. You can control a 49 degree ramp rate comp XER with 155 seat and 425 open pressure. I would not swap the cam until I put the 1.7's on and stiffer pushrods. May also want to consider dropping to a AFR 8019 with 155 seat and 412 open pressure. They list 650 as max lift, but coil bind is at 1.080, so you could run .660-.670 just fine, and you'd be under that with the 1.7's back on. FWIW, I ran the 8019's to .653 lift on the LLSR in my 346 just fine. That was also 11/32 series 5 pushrods.
We all were at one point. No shame in that. And the internet is a tough place to learn, as you have no way to judge your sources. Including me. I will say if I may -- In an earlier post you said a valvetrain expert set up your valvetrain. I am questioning his expertise to be honest.

 

You're awesome. You have a way of saying in three words what takes me sixty.

 

Yep. I have a feeling it may be the pushrods too.
This will be addressed asap.

 

It’s not hard to clearance LS3 heads for 3/8” pushrods. It really doesn’t need much clearancing.

 

Darth, i do not have the 1.7 ratio rockers. Even if I did I wouldn't be able to use them due to my heads having 10mm threads.
The 1.7's had the factory 8mm threads.
So will the 11/32 .120 will fit you are saying in the LS3 head?
137% stiffer sounds like me when I see a woman I find attractive. This is what I would like to use if they fit.
Would you say the 5/16 .105 is going to be sufficient?
In regards to the peak power, because of the mid length runners, power should be peaking closer to 7000rpm before starting to fall away but as we know it is due to the valvetrain issues.

This actually sounds like a good plan of attack.
Start with the push rods, see what happens,
I'm still thinking this it...