Valve spring pressures
09-29-2015 | 06:13 AM
#41
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Spring oilers definitely help cool the springs. I run T&D shaft rockers on my street car. They have an option that have a small hole drilled in each rocker that sprays oil on the springs. Great option to get. I think it was only a $1-2 a rocker option.
09-29-2015 | 08:27 AM
#42
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From: Michigan
Abones, theres a little more to it than that though, 2.300 intake, minus .343 for dia of stem lets say 2.0 " for discussion , 2x 3.14 =6.25" area x 14 psi boost = 85 roughly, so to help control intake valve under boost it would take a extra 85 lbs give or take so really my 490 is more like 405 on intake, take away 5% for springs going away before rebuild interval and even though 490 sounds sorta big it gets small quick, in my opinion. Does a NA motor need 490, no but it better have at least 400 to turn 6k+, Smitty
09-29-2015 | 08:34 AM
#43
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From: On A Dirt Floor
09-29-2015 | 09:11 AM
#44
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From: Michigan
$$$$$ and lots of them, is what I personally don't have, so that is why I try to get a decent power level that will last for a long time and then learn to be happy with it on a low budget engine build, and I think I'm there now.
Thanks to all for the good info,
Thanks to all for the good info,
09-30-2015 | 06:41 AM
#45
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From: Little River SC
09-30-2015 | 02:09 PM
#46
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From: Long Island, NY
03-19-2026 | 04:06 AM
#47
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From: BC
Ice - in fact, some manufacturers are starting to use deeper spring pockets and/or 'cages' (my term) for the lower prt of the springs to hold oil. Helps keep temps down and controls harmonics a little better. As most know now, Cup and some other forms of endurance racing go one step much further, and that is to 'flood' the valve covers with oil.
Your choice of having spring oilers can only help...that's for sure.
Your choice of having spring oilers can only help...that's for sure.
Sometimes tech goes full circle.
03-19-2026 | 04:20 AM
#48
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From: BC
Legitimate question, I am curious to what guys are running for spring pressures, on their big block marine hydraulic roller engines, and how many rpm you turn?
I have catalogs from crane, comp, lunati, crower, isky, elgin, howards, etc. When looking thru their books, most give a spring part number, to go with the cam. Across the board, it seems pretty common, to see a spring setup that comes in around 150ish closed, and 400-450 open pressure for a bbc hyd roller.
For example, the every so popular crane "741" and "651" cams, are spec'd with a crane 99896 spring.
Mine are setup at 165/450ish, pretty consistantly run 5500-5700 wide open, and turned to 6200 on the dyno with no signs of valve float.
Icdedppl is running 225/575 on his crane 651 cams. I know the morel hi rev lifters call for that spring pressure, but , they also are supposed to support 7,000+ RPM, which he will never ever see.
Besides avoiding loss of control, what is the purpose of running high spring pressures? And what are the negatives of too much pressure? Lets just say theoretically, a 160/460 would keep his valvetrain under control at 6000RPM, what benefit is there to having an extra 100psi of force over the nose, if it isnt needed?
What's everyone running for springs?
I have catalogs from crane, comp, lunati, crower, isky, elgin, howards, etc. When looking thru their books, most give a spring part number, to go with the cam. Across the board, it seems pretty common, to see a spring setup that comes in around 150ish closed, and 400-450 open pressure for a bbc hyd roller.
For example, the every so popular crane "741" and "651" cams, are spec'd with a crane 99896 spring.
Mine are setup at 165/450ish, pretty consistantly run 5500-5700 wide open, and turned to 6200 on the dyno with no signs of valve float.
Icdedppl is running 225/575 on his crane 651 cams. I know the morel hi rev lifters call for that spring pressure, but , they also are supposed to support 7,000+ RPM, which he will never ever see.
Besides avoiding loss of control, what is the purpose of running high spring pressures? And what are the negatives of too much pressure? Lets just say theoretically, a 160/460 would keep his valvetrain under control at 6000RPM, what benefit is there to having an extra 100psi of force over the nose, if it isnt needed?
What's everyone running for springs?
I was just going through the Crane catalog, looking for the springs they spec'd for the 731 cam.
Oddly, Crane specs the same 99896 Spring for every cam from the 204deg @0.050" 0.486" lift...to the 262deg @0.050" 0.680" lift Hyd Roller cams.
Seems a bit excessive for the lower lift and shorter duration cams, considering these are milder lobe designs.
Once you see what the valves and springs do at high rpm with high frame rate cameras, you wonder how the valve stems and springs even survive at all. The spring twists when the valve is closed and on the seat...and the stem sways around! This is at 8500rpm, and there's more going on than what we deal with, but the principles are the same.
Seat bounce and issues are also affected by seat materials. Harder seats and narrow seat widths will cause more issues. Valves shed 75% of their heat through the seat contact, and 25% through the step.
