TK 14 SS

I was going to "upgrade" to the LS6 (sodium filled) valves as long as I'm rebuilding the motor and "cleaning up" the heads. But I'm wondering if anybody can tell me advatages/disadvantages of these over a set of new Manley (Race Flo) valves... keeping stock sizes and just cleaning up the chambers, getting a 3 angle valve job, etc...

BTW I spun the #3 rod bearing that's why I'm rebuilding

Spinmonster

Mine is definitely the case you should look at since i went from LS6'ers to manleys. The hollow stems are 2 piece welded shitz that can and in my case, did break. One of my intake valves broke off and destroyed my motor and one head. I now have a forged 348 with new heads and 2.20/1.6 manley race flow/master valves. The manleys are one piece valves. The lighter valves are great for those that want to rev higher but you are better off with more spring pressure and bigger valves. If you are changing valves and having a multi-angle valve job done it is only 100-150 to open up all 16 seats for the next size up valves. The intakes can go to 2.02 on the stock seats and the exhaust can go to 1.6 (not the 1.57 you usually hear about). The bigger valves are definitely worth it.

good luck

TK 14 SS

Allright, thanks for the info I was beginning to wonder if anybody would have any input.

Troy

lsx24

iTrader: (45)

This is excellent info.

Any idea what the weight difference is between the two? Also I'm wondering what causes a 2-piece valve to feel pressure, did a spring break first?

McRat

Before anyone panics who has sodium or hollow valves, Porsche and other hipo motors have had 2 piece hollow valves for over 40 years. While one could come apart, it's really rare without smacking the piston first, and no engine likes that much. Matter of fact, I've never heard any Z06 ever having a valve come apart.

TK 14 SS

Good points!
I do like the idea of the improvement of the LS6 (sodium filled) over the LS1 valves, especially for the higher revving (i.e. Road racing) stuff.
But the idea of new (manley), possibly bigger, valves is good too!

Spinmonster

A few more facts:
1: The spring didn't break, ever
2: the valve didn't hit the piston...no mark and it was a small cam
3: A friend that works at Ramp Chevy in NY verified for me that he knows of at least 5 ZO6 failures for those valves that he himself has worked on. All of them have caused lower engine failure...cracked cylinder walls.
4: the valves are about 65-70% of the weight of a manley raceflow.

For the record, I have to agree that failure is much more likely to happen if the valve hits the piston causing the weld to break. However it is infinitly more likely that a one peice like the raceflow will only bend if they hit a piston such as in a broken spring. So if anyone in this thread is defending hollow stems on the idea that it is due to some other failure that the valve broke, you go right on using them. For me, if I break a spring or some other incident that causes P/V love making, I would rather pay for the head/bent valve than have to go through the crap of swapping engines and paying for the lower end again. To each his own.
Now you all know of 6 instances where a ZO6 head/motor was destroyed from a LS6 valve. I needed to hear only one.....mine. The head of the valve likes to explore. It doesn't stay in the center of the combustion chamber. It goes sideways and rams into the piston cracking it and the oil shoots up into the intake manifold along with chunks of piston, valve guides, valve stem pieces and guess where they go? 1-2-3....ding ding ding....into the other 7 cylinders where they kill the other head and do the same to those cylinder walls. Now if I had raceflows, I would have no damage. If a spring broke, I would have a bent valve and posibly a damaged head. I say be afraid.

TK 14 SS

uh hah!
Points well taken...
I'm seriously having issues here trying to do this better/right and still stay low on cost (otherwise the wife will never let me do anything else), I'd love to just get new heads but that would be pushing it. Like previously mentioned I spun a bearing and am re-doing the bottom end, but while I'm at it I'm trying to gain a little on the heads/valvetrain.

Spinmonster

Buy bare 243 castings and get double springs and the valves of your choice for 200 bucks. If you are thinking there is a measurable difference for the hollow stems, I doubt it. I know many people including myself that rev past 7k with 100gm valves. If you ever break a spring, you will be happy that you have one peice valves.

McRat

Yeah, the GM racing valves are garbage. The endurance racers and Grand Am Cup cars just use them for publicity.

Just for a little piece of mind, do a search of guys who have destroyed their motors on this board. Take a look how many were because of GM racing parts, or specifically the sodium valves and LS6 springs. You are going to find it to be rare.

Consider this, GM says you can spin the sodiums and the Z06 springs to 7500 safely. Take a look at most the spring vendors spec sheets, and look for the RPM.

I'm not saying it can't happen. I'm saying it's less common than most the things that fail when racing these cars. Worry about the stuff that breaks, not the stuff that doesn't. Yes, you can shatter your power-steering pump in an Fbody, I know I did, but I put an OEM one back in, and no more problems.

Spinmonster

impress me:
Do a search to find a raceflow that came apart

TK 14 SS

Wow!
I'm impressed with the amount of thought (passion) that you guys are putting into this. I already have the Isky 295 springs, from when we did the TR224 cam, and the Ti retainers etc...

It's looking more like I will either re-use my valves (they are still okay and only @ 23k miles) or get some Manleys, depending on what the machine shop says about opening up the Valve seats, etc...

Thanks again!
Troy
P.S. Keep up the flow of information, please

Spinmonster

Well you can tell who likes GM hollow stems.

"Yeah, the GM racing valves are garbage. The endurance racers and Grand Am Cup cars just use them for publicity."---not far from the truth....winning with any valve gets you an in with the manufacturer.

You are much better off running a bigger valve that will net you a faster car in the long run than a lighter valve. You will still be able to rev anyway. I can rev to 7500 no problem with no valve float. You have great springs and that is what counts.

lsx24

iTrader: (45)

I'm sure the ~30% weight difference doesn't really apply exactly to lots of horsepower at a lowly 7000 rpms, but it might prolong valvesprings etc. Just as the small difference in titanium retainers which helps the valvetrain remain "nimble", light valves fill a purpose.

There's not doubt that GM did in fact market the "technology" when the Z06 first used them, but as an OEM part I'm sure it was put through more testing than most things we buy in the aftermarket. Was it tested along with 224+ cams and corresponding valvetrain? I doubt they have actually tested the hp back to back which would be a telling test.

Whether or not they are prone to breakage is still surprising to my eyes. Even if there are 10 known breakages, what were the circumstances? What was the application? Who installed them? Were they used? What kind of preventive maintenace was done? Most importantly, was the engine run hard within it's designed purpose or outside of its capability? I would be interested to know what a larger cam would have to gain by running stronger valves (which no doubt the Manley's are). I mean, what kind of stresses do they actually impose? I thought the force was linear "through" the valve, not against the horizontal axis but I don't know the physics.

Regardless of the specs, I'm sure heavier more sturdy pieces can sustain high revs without problems. There are too many variables to these pieces to warrant an exact decision IMO, but that kind of weight loss has to have a positive effect. I would probably play it safe if it were my valvetrain though.

Spinmonster

I agree with you. All the above can have an effect. The fact is that in the real world, springs break, people can do a mechanical over-rev, and pistons and valves will meet. In those events, where all work was optimum and all parts are working as designed, a hollow stem weld can break where the one piece will just bend. I had to buy a new engine due to some fault in a hollow stem. What-ever the benfit they give, I'm not going to use them.

Since I don't know of any hollow stems that come in larger sizes, the benefit of a larger valve outweighs the performance gain from a hollow stem....I would use a raceflow anyday. REV informed me (Oscar) that they will have hollow stem valves in the summer that will come in our sizes.

pekkaz

Maybe, but it's different story if you need to rev 7000 for extended periods. For that you need lighter valves and springs that can take it. I doubt the high pressure springs designed for drag race market would live through a race reliably.

Spinmonster

What the hell are you talking about? Certain racing situations don't let you change from stock set-ups. You may want to check into why Grand Am set-ups are limited in parts choices. If you need a lighter valve then you can get titanium racing valves that weigh less than the hollow stems. REV makes them for any diameter for near 1k per set and they wont come apart if you break a spring. Where did you get your info from???

Drag racing springs as you say can rev to 7500 for as long as you like with one peice valves.

pekkaz

I was not trying to defend sodiums, in fact I have a set of Manleys waiting for next head project.

I'm just stating for that type of racing reliablity is better with lighter valve and less spring pressure. It's completely different world from drag racing. If you make 100 passes, what is it, 20 minutes ... and the car can cool off after each pass.

antz01ta

iTrader: (3)

Here's a good reason to run manley over the ls6
manley = $11 each
ls6 = $46 each

palamesa

Here is mine. Spring broke first...gp