LS Valve weight VS spring pressure

[Monzsta]

Agree, it's just significantly less consequential, than what's on the valve side of the rocker fulcrum

The valve spring has a 1.7:1 leverage ratio working for it, against the push rod and lifter...
at least in the case of an LS

Regardless of rocker ratio It's still inertial mass that needs to be accounted for.

The old "rev kits" that had springs in the valley acting on the lifter took a lot of load off the valve springs. Why did they fall out of vogue?

[turbo camino]

Why don't you try it and let us know how it works out. Worrying about weight on the pushrod side is a great big ol' distraction.

[Orr89rocz]

Agree, it's just significantly less consequential, than what's on the valve side of the rocker fulcrum

Regardless of rocker ratio It's still inertial mass that needs to be accounted for.

The old "rev kits" that had springs in the valley acting on the lifter took a lot of load off the valve springs. Why did they fall out of vogue?

Probably because spring technology and current cam design, along with lighter valvetrain components in some cases, can get it done without additional help. If it truly mattered as much we would see it more often. Might be worth an experiment when playing around with ultra high rpm hyd roller applications…pushing those limits every bit of weight loss probably matters more so than on a solid. Maybe rev kits on lifters may help more at the extreme limits than typical rpm ranges

[Tom68]

Why don't you try it and let us know how it works out. Worrying about weight on the pushrod side is a great big ol' distraction.

I guess another surging spring in the equation isn't necessary when the other components are up to the task, I think they disappeared from Nascar WinstonCup around the same time Shaft Rockers were allowed.

[Walter R. Malik]

Johnson ST2126

ST=short travel

I know, but the spring pressure's are rated @185 seat and 530 open pressure for this lifter, i could be wrong...

Where did you get those numbers ...? Certainly not from Specialty Engine Components; those who manufacture those lifters.

[Walter R. Malik]

Agree, it's just significantly less consequential, than what's on the valve side of the rocker fulcrum

Regardless of rocker ratio It's still inertial mass that needs to be accounted for.

The old "rev kits" that had springs in the valley acting on the lifter took a lot of load off the valve springs. Why did they fall out of vogue?

I used rev kits on small block Chevy "Trans Am" and "Oval Track" engines to keep the roller wheel in contact with the lobe, so the roller wouldn't intermittently lose contact with that lobe; Not to relieve some force needed from the valve springs.
Drag race engines are certainly different than those which require a bit more durability.

[tuffxf]

On some heavy industrial stuff I work on they still use a rev kit ( they don't call it that ) for exacty that reason to keep the lifter on the lobe and therefore extend life.
Cheers

[frnkeore]

There is a formula for determining how the cam side weight relates to the valve side weight:

Cam side valve train weight = 1divided by Rocker ratio ², i.e. 1÷1.76² = .3223 or 1÷1.60² = .39

[bob460]

I know, but the spring pressure's are rated @185 seat and 530 open pressure for this lifter, i could be wrong...

Where did you get those numbers ...? Certainly not from Specialty Engine Components; those who manufacture those lifters.

Walter, like i said i could be wrong.....i found them max pressure's from ISKY cam's website all there Johnson lifters are rated 185/530 pressure's.

[mt-engines]

Where did you get those numbers ...? Certainly not from Specialty Engine Components; those who manufacture those lifters.

Walter, like i said i could be wrong.....i found them max pressure's from ISKY cam's website all there Johnson lifters are rated 185/530 pressure's.

I just don't see why someone would need so much seat pressure with a small, low lift 55mm hydraulic cam.

[Tom68]

I just don't see why someone would need so much seat pressure with a small, low lift 55mm hydraulic cam.

Agreed, but I love high seat pressure anyways, nose pressure has to be balanced carefully though.

[bob460]

Walter, like i said i could be wrong.....i found them max pressure's from ISKY cam's website all there Johnson lifters are rated 185/530 pressure's.

I just don't see why someone would need so much seat pressure with a small, low lift 55mm hydraulic cam.

MT i was referring to Walter's build with .740 lift cam using pac1238x springs and turning 8600rpm.

[Warp Speed]

I just don't see why someone would need so much seat pressure with a small, low lift 55mm hydraulic cam.

Agreed, but I love high seat pressure anyways, nose pressure has to be balanced carefully though.

Why do you "love high seat pressure"?

[Tom68]

I just don't see why someone would need so much seat pressure with a small, low lift 55mm hydraulic cam.

Agreed, but I love high seat pressure anyways, nose pressure has to be balanced carefully though.

Why do you "love high seat pressure"?

No great need, just like to be sure the valve stays shut after it was lowered on to the seat.
Low spring rate spring gives you the nose pressure required and high side seat pressure.
If I over rev and bounce it over the nose and it's hydraulic it pumps up but at least it can help bleed it back down.

[swampbuggy]

Hi Walter,
Thank You, I will call them Monday morn. How do you feel about those PAC1238X springs in an extreme endurance off road 7-8hr race environment? At ~.620" lift I have been using the Erson/FSP PSI springs with incredible longevity.
I'm piecing together a hyd roller 442 cu in LS7 with .675-.700" and up to 8000rpm and contemplating springs now.
Thanks for any advice.

If you have been having incredible longevity from a PSI valve spring, why would you think about changing ? In an endurance engine application
i would make you a bet that there are more Professional organizations using PSI springs than any other brand .