selecting the correct valve spring load rates

grumpyvette

Administrator
Staff member
hey grumpyvette?
I ran across a post of yours from a month or so ago that said you had some experience with the crower 00426 solid roller. I have that cam in my 383 and I have a couple of questions that someone experienced could probably answer.

First... The cam card recommends 115-125 lbs closed/340-350 open spring pressure. Is this correct? This looks WAY TOO LOW to me. I think it may be a typo. The springs I chose to use are 166 closed/400 open which still seems light.

Second... With my 383 power peaks at only 5700 rpm. It doesn't seem right at all. I have dyno'd it to verify this. It made 355hp/360tq to the wheels. Does this match your experience with this cam? I would expect power to peak closer to 7k.


you always need to look carefully at the total component list and the intended application, when selecting the valve train components, as rpm levels increase, theres a requirement for spring pressures and valve train stability to be increased and components like cast iron cam cores can become a reliability concern, Every choice is a compromise in some area,
get the valve spring load rates to low and youll loose valve train control at some point in the rpm band which will quickly result in a failed valve train, but get the load rates to high and durability suffers from wear or component stress failures,and increased friction, so swapping to forged billet cam cores and rocker stud girdles becomes mandatory to maintain valve train stability at some point.If your running a CAST cam core youll want to select valve springs with lower lifter load rates, that you can use with a forged BILLET cam core. Increased load always means reduced service life. employing drag race valve springs in the 600 lb. or higher open load Range will reduce the life of your roller bearings between rebuilds much the same as will employing high-impact roller cam profiles.you can use lower valve spring load rates on roller cam valve trains to significantly extend durability but at the cost of reducing valve train stability at upper rpm ranges
I can easily see why you might be confused, if you read enough internet commando posts you'll very quickly get the idea that hydraulic roller lifters will last a great deal longer than solid roller lifters. (thats frequently the case mostly because solid roller lifters are run with much higher valve spring load rates and spun up to much higher rpms thus operate under much higher stress, if both types of valve trains were run under similar stress and rpm limitations both styles would have similar life expectancy)
but what the vast majority of the posters fail to mention is that the valve spring load rates and peak rpm expectations , plus the basic cam core materials, and valve train quality, all can vary a great deal, and in general, the solid roller lifters are generally lighter in mass(weight) so that they can and will operate safely to slightly higher rpms with identical valve spring load rates, compared to the heavier hydraulic roller lifters, but remember you'll need to match the valve spring load rates too the intended inertial loads the valve train will be expected to see, during its intended operational rpm band.
if you run an engines rpms up to the point the lifters loft, of FLOAT, ( or leave the cam lobe surface due to inertial loads exceeding the valve springs ability to maintain lifter to cam lobe contact, valve train damage will usually quickly follow)
your generally going to see stock O.E.M. valve springs start to not be able to control hydraulic rollers at about 6000 rpm, and remember valve springs have a tendency to loose the load rates as the stress and age of the valve spring in use is extended, so a new set of O.E.M. valve springs that controlled the valve train very effectively for the first 10K-20K miles will no longer have anything like the original resistance or load rates after 20K miles in most cases.
any time your building a new engine youll want to talk to several engineers at several cam manufacturers to discuss, carefully matching...
the cam and valve train components youll want to use and the limitations of the parts you'll select, discuss the cams intended operational rpm range the cars weight, drive train and rear gear, tire size, basic lobe lift, duration, lobe separation, engine displacement and compression, along with the valve spring load rates lifter design, rocker ratio, and the potential use of a billet or hardened cam core.
P1-CHARTS.jpg

related info

The following recommendations are from Erson Cams. If you have questions, you can reach their tech department at 800-641-7920.

Hydraulic Flat Tappet Camshaft: 110 lbs Seat pressure/250-280 lbs open pressure

Solid Flat Tappet Camshaft: 130 lbs Seat Pressure/300-325 lbs open pressure

Hydraulic Roller Camshaft: 130-140 lbs Seat Pressure/300- 355 lbs open pressure

Solid Roller Camshaft: (Minimum Safe Pressures DEPEND ON SEVERAL FACTORS)

Up to .600˝ valve lift: 200-235 lbs Seat Pressure/600 lbs open pressure

Over .600˝ valve lift: 250-280 lbs Seat pressure /100 lbs pressure for every .100˝ of valve lift

due too the design of most rocker stud girdles and the locking nut designs in many cases your choices will be limited ,
but I prefer to keep the lower rocker girdle surface a minimum of about .060 from any portion of the roller rocker in its arc if I can manage that


prctool.png


SOME ROLLER ROCKERS CAN AND DO BIND ON ROCKER STUDS, or rocker adjustment nuts, youll need to check carefully
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some roller rocker too retainer combo clearance issues cause problems easily solved with beehive springs and smaller retainer diameters

beehivesprcl.jpg


the POLY LOCKS that are used with most roller rockers AND ROLLER ROCKER SIZES, (come in a variety of lengths AND DIAMETERS AND THREAD SIZES) so you might find you need tall valve covers to allow clearance BUT in most cases swapping to shorter poly locks reduced that problem from mandating taller valve covers, be aware that the outside diameter of the locks is a darn important factor in allowing the rocker to reach full potential lift!
it should be obvious that youll need to carefully check clearances over the full rotation and lift in several areas if you chance valve train components and retainer to rocker and internal rocker clearance slot to poly lock are two of many potential places the valve train may bind if theres not the correct clearance

rockerh1.png

rockerh2.png


rockerbin.jpg

rockertrunion1.png

retain6.jpg


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http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

http://garage.grumpysperformance.co...-the-extra-cost-vs-a-flat-tappet-design.3802/

http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

http://garage.grumpysperformance.com/index.php?threads/rod-bolts-rpm-vs-stress.341/#post-30778

http://garage.grumpysperformance.com/index.php?threads/redline.343/#post-58215

http://garage.grumpysperformance.com/index.php?threads/what-springs.11352/#post-51835

http://garage.grumpysperformance.co...ulic-roller-lifter-selection.5522/#post-16620

http://garage.grumpysperformance.co...ng-pressures-don-t-work-well.1489/#post-16234

http://garage.grumpysperformance.co...rect-valve-spring-load-rates.4680/#post-12650

http://garage.grumpysperformance.com/index.php?threads/small-base-circle-cams.3810/#post-10118
READ THRU THESE LINKS
viewtopic.php?f=52&t=788&p=10777&hilit=cast+core#p10777

viewtopic.php?f=52&t=181&p=9294&hilit=cast+core#p9294

http://www.amotion.com/tech/camtalk.html

http://johnmaherracing.com/tech-talk/fl ... rs-part-1/

http://www.hotrod.com/how-to/engine/ctr ... ubricants/

viewtopic.php?f=52&t=2166&p=5840&hilit=cast+core#p5840

viewtopic.php?f=70&t=1701&p=5252&hilit=cast+core#p5252

http://www.hotrod.com/how-to/engine/ctr ... ubricants/

http://www.alexsparts.com/valve-spring- ... yd-roller/

http://www.superchevy.com/how-to/engine ... ller-cams/

00426crower.jpg

look at the valve spring load rates above, obviously meant for long street driving and not peak high rpm power potential
00427.jpg

then compare them to this very similar cam (00427)and its recommended valve spring load rates...obviously the 00426 has springs selected for street use and the 00427 for maximizing track performance
the cam your talking about is a good sbc race style roller race cam

a0543d16.jpg

keep in mind roller cam wear tends to occur over time, and usually theres obvious signs of wear that indicate things are about to degrade so anytime you get the chance inspect the components for those wear indications as it might allow you to replace defective parts before things get expensive


your correct that cam requires a spring that has about a .650 clearance and about a 180-190lb seat and 450-470 lb open pressure , and yeah, 6500rpm plus should be easily done
your correct to question things that don,t seem to follow common sense

RECOMMENDED VALVE SPRING INFORMATION:
Part # 68363 Dual springs
Approximate spring pressure: valve closed: 190/210 LBS.
valve open: 450/470 LBS


read thru these links

viewtopic.php?f=52&t=181

http://www.racingsprings.com/Store/Prod ... egoryID=13

http://www.racingsprings.com/Store/Prod ... ductID=241

http://dairally.net/daihard/chas/MiscCa ... Spring.htm

http://www.chevyhiperformance.com/techa ... index.html

http://www.nitemareperformance.150m.com/ZDDP.html

http://www.cranecams.com/bulletins_listview.php?s_id=16

http://www.popularhotrodding.com/engine ... ables.html

http://www.tomorrowstechnician.com/Arti ... ology.aspx

http://www.classicinlines.com/springs.asp
 
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