Hollow stem valves

[jaf2021]

Any performance gains by using hollow stem valves?? Pros and cons??

[rx dealer]

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]

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]

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]

Originally Posted by rx dealer

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]

Originally Posted by Rob Wright

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]

Originally Posted by Rob Wright

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]

Originally Posted by rx dealer

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]

Originally Posted by Ed Wright

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]

Originally Posted by Rob Wright

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?