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-   -   Hollow stem valves (https://classracer.com/classforum/showthread.php?t=66898)

jaf2021 07-14-2017 03:00 AM
Hollow stem valves
 
Any performance gains by using hollow stem valves?? Pros and cons??

rx dealer 07-14-2017 11:21 AM
Re: Hollow stem valves
 
Jaf, I bought a set manley solid valves for my LS3. The hollow stem were 6-8 weeks out and $250 more for a savings of only 9 grams a valve. that might seem little but x 16 valves and that adds up. So the new valves, heads,cam, lifters,rockers along with the factory hollow stem valves all went on a spintron to see where i stand and valve control was good to 9400 RPM. on both solid and hollow stem. point is I don't think it matters. I was worried having heavy valves but the spintron proved me wrong. I did find out that my valve springs were too heavy on the seat. I hope this helps...Luke SS 311

Mike Pearson 07-14-2017 12:22 PM
Re: Hollow stem valves
 
I have not had good luck with Manley valves of late. I have lost 2 engines recently due to exhaust valves dropping the head off. What are you using for exhaust valves? 350 super stock engine. Anyone else having this issue?

rx dealer 07-14-2017 01:13 PM
Re: Hollow stem valves
 
Mike, this engine is a 396 LS3 COPO Super Stock engine. I use the extreme duty XH-432 exhaust valves from manley. A friend lost 2 engines ( 396 big block stocker ) using another top brand valve. is it the luck of the draw? who knows. fingers crossed...Luke SS 311

Rob Wright 07-14-2017 01:58 PM
Re: Hollow stem valves
 
Quote:
Originally Posted by rx dealer (Post 539430)
Jaf, I bought a set manley solid valves for my LS3. The hollow stem were 6-8 weeks out and $250 more for a savings of only 9 grams a valve. that might seem little but x 16 valves and that adds up. So the new valves, heads,cam, lifters,rockers along with the factory hollow stem valves all went on a spintron to see where i stand and valve control was good to 9400 RPM. on both solid and hollow stem. point is I don't think it matters. I was worried having heavy valves but the spintron proved me wrong. I did find out that my valve springs were too heavy on the seat. I hope this helps...Luke SS 311
It matters a lot if you have a cam with "iffy" lift curves. You can easily lose 1,000 RPM of peak limiting speed by changing to solid stem from hollow in some combinations.

For heads popping off valves, I'll bet a hundred they had severe bounce at closing. That's generally what will make things break. Good thing some people test this stuff. ;)

junior barns 07-14-2017 03:22 PM
Re: Hollow stem valves
 
Quote:
Originally Posted by Rob Wright (Post 539441)
It matters a lot if you have a cam with "iffy" lift curves. You can easily lose 1,000 RPM of peak limiting speed by changing to solid stem from hollow in some combinations.

For heads popping off valves, I'll bet a hundred they had severe bounce at closing. That's generally what will make things break. Good thing some people test this stuff. ;)

you mean too much seat pressure or not enough???

rx dealer 07-14-2017 05:37 PM
Re: Hollow stem valves
 
Quote:
Originally Posted by Rob Wright (Post 539441)
It matters a lot if you have a cam with "iffy" lift curves. You can easily lose 1,000 RPM of peak limiting speed by changing to solid stem from hollow in some combinations.

For heads popping off valves, I'll bet a hundred they had severe bounce at closing. That's generally what will make things break. Good thing some people test this stuff. ;)
I wonder who recommended the spintron test...well worth it.. no guessing or mismatch parts...Thanks Rob!! Luke SS 311

Ed Wright 07-14-2017 05:47 PM
Re: Hollow stem valves
 
Quote:
Originally Posted by rx dealer (Post 539430)
Jaf, I bought a set manley solid valves for my LS3. The hollow stem were 6-8 weeks out and $250 more for a savings of only 9 grams a valve. that might seem little but x 16 valves and that adds up. So the new valves, heads,cam, lifters,rockers along with the factory hollow stem valves all went on a spintron to see where i stand and valve control was good to 9400 RPM. on both solid and hollow stem. point is I don't think it matters. I was worried having heavy valves but the spintron proved me wrong. I did find out that my valve springs were too heavy on the seat. I hope this helps...Luke SS 311
What did you see on the Spintron that indicated too much seat pressure?

Rob Wright 07-15-2017 01:55 PM
Re: Hollow stem valves
 
Quote:
Originally Posted by Ed Wright (Post 539455)
What did you see on the Spintron that indicated too much seat pressure?
It generally just didn't look as smooth with more deflection near the nose and a little bit of drumming at the closing point. 150 lb less spring Force cleaned it all up and made it look beautiful.

High spring force is definitely not your friend all of the time.

Jim Hanig 07-15-2017 02:04 PM
Re: Hollow stem valves
 
Quote:
Originally Posted by Rob Wright (Post 539495)
It generally just didn't look as smooth with more deflection near the nose and a little bit of drumming at the closing point. 150 lb less spring Force cleaned it all up and made it look beautiful.

High spring force is definitely not your friend all of the time.
How much did you have on the seat?


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