My Gen II Hemi starts to break up in the 6000-6500 rpm range. This was not the case originally but has started in the last year or so. It only has a few thousand miles on it. Build is 4-5 years old.
Cam is a Lunati hydraulic roller: 231/235 @ .050"; .535/.550 lift.
Springs (recc. by Lunati) are installed at 139# on the seat and 325# open (per their recommendation).
Valve gear is all stock.
Does that sound like enough spring?
Or any other thoughts are welcome. Thanks.

Doesn't sound like enough spring to me but that isn't the only factor.

Weight is as well, so if you are running a large diameter spring I would replace it with something with more pressure, smaller overall diameter and Ti retainer. (Not that it was asked but I would prefer solid roller as well)

That being said your current spring pressure may be enough if they are beehives.

Next I would make sure you have stiff enough pushrods.

You sure it's not ignition related? I'd be swapping out coil or ignition box before I pulled a valve spring unless you find broken ones (could be product of valve float).

Those seem light....Hemi's are very sensitive with respect to valve train. If its not lean, I would swap springs.

I'd rule out the ignition system first.

I also agree that those spring pressures seem light for a heavy hemi valvetrain.

Before we were smart, the Hemi we raced would shoot ducks at 6500 in the 1/4 mile, we only ran 1/8 mile tracks, we re jetted, changed plugs, wires and cap. We were running ONE holly blue with the cross ram and Hollys, was a while before the light came on that we DIDNT have enough fuel in the first place. Check your carbs and fuel supply. How did I learn? I was wrenching on the buddy’s 69 Stang with a 588 cu in Shotgun Roush engine, twin dominators at over 830 hp, popping on the top end same way (8.90 @152) a pro stock guy clued us in, you guessed it, one holly blue. In 1983 no less.

Thanks for the responses guys.
I didn't mention initially but this is a street car, 477 C.I. with FAST EFI (throttle body). Fuel pressure is 45-47 psi.
Ignition is an MP chrome box, recurved distributor, and a 45kV coil.
The condition started after a couple of years. It's not driven much. Used to pull rock solid up to 6500; I don't push it much beyond that.
I recently read an old article about Dudek's Hemi and he said it wouldn't buzz past 5000 with 160# / 390# springs (with a similar cam). Just got me thinking about the springs.
So, for the ignition check out, can I bypass the ballast for a quick test. Seems I've done that in the past.

Can you drive around it ? Meaning if you lift just a bit does it go away?
I had a problem once that turned out to be a clogged fuel filter . symptom was similar.
Start with simple .

Do you have a data log or screen shot of such?

Condensation bites me every year. Try some drygas. I kid you not.

It sounds like ignition miss to me or the valve springs.
I use to race NHRA stock back when we had to use the original stock valve spring and cam specs, the first motor was a 1968 Street hemi that had 125 lbs. on the seats and 325 Lbs. open with stock lift which was right at .484 lift at the retainers on the intake valves and right at .466 net on the exhaust side, we switch the first motor into a 1970 Challenger with a hydraulic lifter cheater cam and use the same valve spring specs on it, both motors would pull really hard to 7000 RPM with a Hayes S4 ignition box, now known as Stinger ignitions.
I race another NHRA stocker 1970 hemi car with the early Mopar chrome box with the blue heat sink and it would pull hard to 7000 RPM also
My message is to try one thing at a time but in your case I would look at the valve springs first
Did you modify the oil system in the block to oil the rockers full time? If not that is worth doing , Especially on a street motor that gets the oil hot and valve springs hot for long periods of time
I groove the #4 cam journal to do that and restrict the holes size to the rocker arms depending on which rocker arms are on the motor, roller rocker on the shaft get a .040 oil restrictor, non roller rockers on the shaft get no restrictor
On your deal I would look at 225+ lbs. on the seats and 480 Lbs.+ open depending on how much net lift you have. If over .600 net lift look at 580 to 650 Lbs. open pressure and near 250+ lbs. on the seats
you can NOT hurt a steel core solid roller cam with to much valve spring pressure, you can tear up the rollers with to little
If you can see bright stripes on the back side of the outer edge of the cam lobes you don't have enough valve spring pressure

He's on a hydro roller though ^

With smaller diameter spring, ti retainer I would guess somewhere in the 180/425 range.

I've ran more on hydraulic roller but can start tracking/damaging the cam if a 5150 core

I've never seen a hydro go past 6500 in a hemi without a lot of work. I'd bet it's just that it's a hydro. More spring will help, but only to a point.

This. The HEAVY valve train in a Hemi does not like hydraulic cams.

What he said. I have a 528 that just wouldn't run past 6000. Hyd roller. Ray Barton says that they start floating at 5 something. I'm in the process right now of changing to a solid roller. The engine acted lazy.

The limits of a hydraulic roller makes sense but how did he pull 6500 rpm before?

What is the reason it wouldn't rev with a hydraulic?

I don't like the idea of running one on a hemi due to pushrod angularity but can't think of any reason you -couldn't- get it to 7k just because it's hydraulic

The rockers with the crazy push rods are just to heavy for a hyd to handle. The spring pressures required won't work with a hyd.

I guess that's the reason I ask as far as what specific to Hemi as I've ran 200 seat 450 open and nearly 8k rpm on other hydraulic roller engines with 1.8 rockers and smaller diameter lifters.

With 1.8 rocker that would put 360/810 pound load to the lifter. With the same spring pressures on a hemi and say 1.52 ratio that would put 304/684 pound load to the lifter.

I could see the hemi not getting there due to mass of rockers but don't think pushrod weight should matter much. (at least I've not seen weight on the actuation side clip usable rpm range).

Either way, agreed that I don't like the idea due to pushrod angularity, just wondering if anyone has actually tried higher spring pressure and lighter valves/springs/retainers with hyd roller on a hemi or just didn't as they assumed the lifters couldn't take it.

A wedge with a hydro roller is a completely different animal, and no where near the same load on the valve train. Weight, compound angles, length, length of rocker ect. When you start going to ti valves, retainers, locks, spread lifters, and tons of oil management to make a hydro work, you're already where no one wants to go. Better to buy a high quality set of solids, a small mechanical, and rev to the moon whenever ya want.

I get the desire to run a hydro on the street, but beyond that, it seems like wasted energy to me.