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At what point do you make the switch? And what is considered a heavy intake or exhaust valve for a solid roller Ls build? Back 20 years ago it wasn't uncommon to spin a sbc or bbc 7800 to 8200 rpms with heavy stainless valves without issues. It seems like cam lobes and valve spring technology have came a long ways since then. Just curious.
 

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We always used about 8000 rpms as a guideline for going titanium, not very scientific, but it's a guideline...
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Brian,is that going from a hollow stem valve to ti,or plain stainless solid stems?
thanks
 

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Discussion Starter #4
We always used about 8000 rpms as a guideline for going titanium, not very scientific, but it's a guideline...
That's what I was always taught also. Being realistic mine should make it's peak between 7500-7800 RPMs. My intake valve is 125g and the exhaust is 95g so I should be fine with 315/810 on my spring pressures.
 

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The heavy valve will bounce like a mofo.
 

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All depends on the lobe profile. Very smooth stable one will run all day with that valve. Do it with 100-200 pounds less and valves that heavy Then again, lighter is always better there
 

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Valve size (weight) is the determining factor... I don't think there's an actual rpm thresh hold that can't be broken. Cam lobe (how agressive) is the other factor.

Example.. a 2.2 stainless intake valve might only be stable to 7800, whereas a 2.11 intake valve, all the same valvetrain etc might be o.k. to 8100.

It's the weight vs how much and how fast are you trying to move it.
 

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Valve size (weight) is the determining factor... I don't think there's an actual rpm thresh hold that can't be broken. Cam lobe (how agressive) is the other factor.

Example.. a 2.2 stainless intake valve might only be stable to 7800, whereas a 2.11 intake valve, all the same valvetrain etc might be o.k. to 8100.

It's the weight vs how much and how fast are you trying to move it.
I agree, I guess it would be more of a question for whoever is grinding your cam.
 

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Essentially, yes. They can tell you what the lobes are going to need for valve spring with what size valves you are running... The guy doing the the heads should be able to tell you a limit on what's reasonable as far as lobe design as well, lift, etc.... or make an adjustment when setting the heads up spring wise to what you want to do cam wise.
 

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Brian,is that going from a hollow stem valve to ti,or plain stainless solid stems?
thanks
Plain stainless 11/32", I'm sure 8mm, 5/16" and hollow stem could probably go more rpm.

Anything you can do to shave weight off the valve side will help RPM, including spring weight. A dual spring with 340 lbs on the seat will rpm better than a triple spring with 340 lbs on the seat. There's probably 60 grams difference between those.

Interesting list of weights I put together 8 years ago. One of the first 10,000 rpm engines that I ever saw had standard 7 degree locks, but they're almost half the weight of a a Super 7 or 10 degree... http://www.totalengineairflow.com/tech/valvetrainweights.php
 
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