roller rockers, , which is best,steel or aluminum"

[grumpyvette]

aluminum or steel rocker arms?

well the first issue most guys look at is the rather obvious weight difference,between the two materials, but remember the size of the rocker trunnion and circumference of the rocker bearing does matter in the load carry capacity, and tendency to wear as does the bearing surface area, and its ability to dissipate heat, and the materials reciprocating mass. because as the weight of the valve train goes up the ability of the valve train, to rapidly respond to changes in rpm decreases due to inertial loads.
the truth is that steel is significantly stronger than aluminum and has noticeably higher wear resistance for the same material thickness, but steel is also heavier.
Elastic modulus
Steel at 210 GPa, has three times the elastic modulus compared to aluminum's 70 GPa. Steel has three times the elastic modulus as aluminum. Related to stamping performance, aluminum will possess higher springback than mild steels. Even compared to high strength steels, strength level to strength level, aluminum will still possess higher springback.
Advantage: Steel
Fatigue
Aluminum fatigue performance is less than ½ that of steel. This is a very important advantage for steel in terms of vehicle life durability. Automotive steel grades also possess an endurance limit. From testing, it was found that structural aluminum grades (5XXX series) will not reach an endurance limit, but continually degrade at higher cycles. The following figure indicates this pictorially:

IF the roller tip of a roller rocker arm is doing it's job the way it is supposed to then the wipe pattern across the valve tip is of little consequence as long as it remains away from the edge of the valve stem, as its designed too reduce friction, but its not the roller tip moving accross the valve tip that produces most of the friction,its the roller bearing on the trunnion where , the rocker studs are thru the bearing,that handle easily 95% of the friction, ."
now obviously you can design thinner and stiffer components from steel, of a given thickness than an equally thick aluminum component strength level so theres a balance or compromise thats made, you can make far stronger steel components of a similar thickness or thinner steel components having about equal strength to the thicker aluminum component.
it should also be obvious that the QUALITY of the bearings and CHOICE of MATERIALS and care taken during manufacture has a huge effect on the durability of the finished product.
as a rough average depending on alloy used you can assume aluminum will weigh about 35% less than steel of the same component dimensions
Surprisingly, the steel chrome moly steel rockers can be actually lighter from the valve spring's point of view.
Even though the steel rockers may have more overall weight, they can have less bulk further from the fulcrum (pivot point) than aluminum rockers. Therefore they have a lower "polar moment" of inertia and change their rocking direction with slightly less effort. remember the bearing axle or trunion can be larger and the bearing surface larger, with a steel rocker because the part of the rocker rotating around it can be made thinner and still maintain the same or greater resistance to deflection under high pressure loads, this is important because increased bearing diameter can provide significantly more strength and that center axle does not rotate or add inertial mass so its not slowing the valve train down.

Steel has what is called a fatigue limit. If you keep the stress in a steel part below a known critical level, that you can design the parts for, you can flex it indefinitely and it will never break. Only when you exceed the fatigue limit do you have a problem. If you exceed it slightly, you weaken the metal and effectively lower the limit. You can still flex it indefinitely without breakage so long as you keep it under the new fatigue limit.

Aluminum has no fatigue limit. That might sound good, but it's not. What it really means is that no matter how little you stress aluminum, if you cycle it enough times, it is going to fail. There is no "keep it under this point and you'll be safe," failure is guaranteed, the question is simply a matter of when it will fail.

IF YOUR REALLY PAYING ATTENTION youll generally find the center axle and bearing size in the better steel rockers is significantly larger and more durable in the steel rockers vs the aluminum, because the rocker body on the steel rocker can be made about 30% thinner yet still be stronger
as long as you select good quality name brand roller rockers you can usually depend on steel rockers having a significant strength and durability advantage and aluminum having a slight rpm advantage due to lower mass resisting inertial loads, this gives a couple of hundred rpm advantage, at best in some engines,less in most, but below a valve float limitations.

thinking about putting roller rockers on my 327.

IM seriously considering/ thinking about putting roller rockers on my 327.do i have room to put 1.6 ratio or just stay with 1.5s http://garage.grumpysperformance.com/index.php?threads/louis-tool-swapping-to-1-6-1-ratio-rockers.14761/...

garage.grumpysperformance.com

Steel also does not fatigue nearly as fast, over as many load cycles like aluminum does. thats why aluminum rockers are usually changed out after 30K-50K miles as an expendable item like belts and hoses but steel rockers can be rebuilt with new roller bearings
aluminum will eventually fail, in most cases simply because they will eventually fatigue faster. That is simply due to the repeated heat and stress cycling of the aluminum. Comp Cams, CROWER and several other sources make a stainless rocker or shaft rockers that actually have less rotational weight than your average aluminum rocker. The resistance to metal fatigue properties of the properly heat treated stainless create a much longer expected lifespan because it is not affected by heat and stress cycles nearly as much.

both materials have their strong points, and if your looking for the lightest weight rockers aluminum seems to be the obvious choice ,and steel rockers can be made thinner so clearance issues with other valve train components tend to be less common that with the thicker aluminum rockers, but its not just the total rockers weight but the reciprocating weight, and rigidity of the lifter,push-rod, and retainer and valve string loads that must be considered and the distance that weight is from the pivot point that matters to some extent to your valve train,, its the total inertial, loads that will effect your upper rpm valve train stability , and upper rpm limits
a good aluminum roller rocker design like the ERSON EXTREME ROCKERS provides you with a few extra rpm due to the lighter weight, and its a great choice for a weekend toy that gets run hard but sees low mileage
but for long term durability Id select the newer comp steel rockers for a street strip application

stamped rockers are cheap and dependable but decent roller rockers will frequently allow the engine to run at reduced friction loads, 10-15 hp gains are easily available, and in some cases even more is available especially with higher spring loads or a higher than stock rocker ratio.
Ive suggested these newer comp cams rockers on several builds as Ive seen good results

pre-spraying all bearing and valve train components with a moly based spray, helps embed micro moly lubricants in the metallic surface micro fissures , a good paste lube like cranes assembly lube over the spray surface helps insure a good lubricant surface coating, that is far stronger than just the ZINC and PHOSPHATES in oil

Proper push rod length is absolutely critical for peak performance—minimizing bent or broken valve stems, guide wear, and energy-wasting valve side-loading friction.
With the lifter located on the round base circle, position the Push Rod length Checker (make sure you have the Checker with the proper diameter hole) over the stud. Ideally the Checker should contact the top of the push rod and the valve tip evenly at the same moment, should the Checker contact the push rod first, measure the gap between the front of the checker and the valve tip, and purchase a shorter push rod of the correct length. Should the Checker contact the valve tip first, measure the gap between the back of the Checker and the top of the push rod, and purchase a longer push rod

http://www.summitracing.com/search/...d-length-checkers?autoview=SKU&ibanner=SREPD5
Proform Pushrod Length Checkers 66789 SBC 3/8" rocker studs

Proform Pushrod Length Checkers 66790 SBC 7/16" rocker studs

Proform Pushrod Length Checkers 66806 BBC 7/16" rocker studs
http://www.summitracing.com/parts/CCA-1601-16/

READ THESE RELATED LINKS VERY CAREFULLY
http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

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

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/#post-54232

some roller rocker too retainer combo clearance issues cause problems easily solved with beehive springs and smaller retainer diameters

look through this thread
http://garage.grumpysperformance.com/index.php?threads/two-loose-valve-locks.9687/#post-47884

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

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

STUD GIRDLES ADD A GREAT DEAL OF RIGIDITY TO THE VALVE TRAIN
the older comp chrome moly rockers work well but on some applications had clearance issues with spring retainers

Ive used the previous or older design comp cams steel rockers on lots of engines with good results, that the newer design has recently replaced, the older design with the advantage of having a slightly stronger and lighter design and having more retainer to rocker clearance, btw lash caps on the valve stems can be used to increase clearance in some cases, if your having that problem but their use, may require longer push-rods
http://www.summitracing.com/parts/CRN-9 ... N-99421-16

remember the object is to maintain the proper valve train geometry, to have minimal side loads , and the roller rockers lower friction resulting in low heat as well as maintaining the lighter valve train, with the new components

but Ive also used these two rockers
ERSON extreme duty

http://www.pbm-erson.com/store.php?catId=24

which Ive used for dozens of engines over many years with ZERO FAILURES so far, just be aware that the extreme duty rockers are ,a more robust design that the standard ERSON rockers which I don,t recommend

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

and the CROWER stainless ROCKERS
http://www.jegs.com/i/Crower/258/73670-16/10002/-1

theres ARE big differences in the quality of the metal and hardness, look closely at the PROCOMP Chinese rockers above, notice the tip of the rockers axle, its obviously been flared,like a rivet indicating a fairly soft metal, rather than forced into place with an interference fit like the comp cams rockers they try to duplicate

BTW if your thinking about getting those stamped steel, roller tip rockers , DON,T!!, they have a tendency to fail, and they don,t handle high spring pressures well, and they don,t reduce friction much so they are basically a (FEEL AND LOOK GOOD" part that doesn,t do much constructively

Because, easily 90% PLUS of the friction in the valve train is NOT on the contact between rocker arm tip and the valve stem, so swapping to a roller tip on a rocker provides negligible benefits in friction reduction.
you can buy decent quality full roller rockers, for well under $250-$350
and roller tip rockers commonly cost 1/2 or more of that making the full rollers a much better option



obviously valve float and improper lash clearance can cause problems but in some cases, lash caps can reduce wear

in most cases when you see valve tip damage like this its the result of valve float or a weak valve spring , in many cases youll need to swap to a higher spring load rate and new springs to prevent or reduce this damage

read these threads

viewtopic.php?f=52&t=2632&p=6790&hilit=louis+rocker#p6790

http://www.circletrack.com/techarticles ... index.html

viewtopic.php?f=52&t=3009&p=7985&hilit=roller+rocker#p7985

viewtopic.php?f=44&t=737&p=1034&hilit=louis+rocker#p1034

viewtopic.php?f=52&t=198&hilit=louis+rocker

viewtopic.php?f=52&t=181&p=215&hilit=louis+rocker#p215

viewtopic.php?f=52&t=2746&p=7513&hilit=rocker+stud#p7513

http://www.americanmachinetools.com/ten ... rength.htm
http://www.ami.ac.uk/courses/topics/0123_mpm/index.html
http://www.lunatipower.com/Tech/Valvetr ... metry.aspx

Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip

Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.

Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.

viewtopic.php?f=44&t=2839&p=7344&hilit=adjustable+guide#p7344

viewtopic.php?f=52&t=126&hilit=louis+rocker

pictured above you see the last rocked badly out of alignment with the valve center line,
a good example why you need adjustable guide plates, this rocker if left too run off center like this, on the valve stem tip , will quickly destroy the valve guide and rocker

and you may need too use the correct adjustable guide plates when you find the push-rod alignment is in need of minor tweaking to get the clearance and geometry correct,
don,t forget as many guys do, that swapping to a higher ratio rocker changes the push-rod rocker geometry,and clearances, the heads and rockers used obviously effect the required clearance, but you'll usually want at least 60 thousands clearance on the push rods to slot measurements and you'll want to rotate the engine thru two complete revolutions while verifying that clearance, while watching the push-rod geometry as it changes as the rockers move thru their arcsand may require a different length push-rods.

using a louis tool, this tool is a GUIDE /tool for use with a high quality DRILL,its made of HARDENED STEEL that FORCES the DRILL BIT to drill thru the head to correctly lengthen the pushrod slot for increased clearance, they usually come WITH INSTRUCTIONS AND THE NECESSARY DRILL

 

[grumpyvette]

its hardly surprising when getting your rocker geometry's a challenge, its not like they make it standard or easy
ERSON,CRANE and CROWER tend to have good consistent dimensions
and some of the off shore imports are a joke in consistency
comps rockers rocker angles vary a good deal between models, but all can be made to function

notice the significant difference in the trunnion bearing diameter between the larger bearing in the steel rocker above VS the smaller axle or trunnion in the aluminum rocker,while there are aluminum rockers with replaceable bearing they are not as common
The result of the 30% plus stronger steel material, used.
that axle or trunnion is the heaviest component and does not rotate,​

the roller bearings rotate around it. notice its a replaceable wear item on the steel rocker VS a smaller pressed in bearing in the aluminum rockers that are designed and expected to be replaced regularly as aluminum fatigues so replacing just the bearings still leaves them subject to failure after hundreds of thousands of stress cycles

the

it should be obvious that the slot clearance in some rockers , especially with poly locks significantly limits rocker movement before clearances become an issue
http://www.crower.com/media/pdf/2008b/153-155.pdf

http://www.lunatipower.com/Tech/Valvetrain/HowToVerifyValvetrainGeometry.aspx
keep in mind all roller rockers do not have identical dimensions, crower offers .050 off set trunion designs ans the designs dimensions do differ slightly between manufacturers

BEEHIVE SPRINGS and FORGED STEEL ROCKERS GIVE A GOOD DEAL MORE ROCKER TO RETAINER CLEARANCE

Elastic modulus
Steel at 210 GPa, has three times the elastic modulus compared to aluminum's 70 GPa. Steel has three times the elastic modulus as aluminum. Related to stamping performance, aluminum will possess higher springback than mild steels. Even compared to high strength steels, strength level to strength level, aluminum will still possess higher springback.
Advantage: Steel
Fatigue
Aluminum fatigue performance is less than ½ that of steel. This is a very important advantage for steel in terms of vehicle life durability. Automotive steel grades also possess an endurance limit. From testing, it was found that structural aluminum grades (5XXX series) will not reach an endurance limit, but continually degrade at higher cycles. The following figure indicates this pictorially:

http://www.summitracing.com/parts/crn-11759-16

cranes gold roller rockers are decent quality rockers for a small or big block chevy,Ive used those, ERSON, CROWER and COMP CAMS ROLLER ROCKERS, many of them come with jam nuts that require a 3/16" allen key
and look a great deal like these posted here below

but these are NOT locking jam nuts designed to work with a rocker stud girdle

http://www.summitracing.com/parts/tfs-3 ... /overview/

BTW.IF YOUR BUILDING A SBC
http://brodix.com/heads-2/small-block-chevrolet-compatible-heads/ik-series
http://www.jegs.com/i/Brodix/158/1021001/10002/-1

brodix ph# 1-479-394-1075 (ALWAYS VERIFY PART NUMBERS SEVERAL,
TIMES FROM AT LEAST TWO SOURCES, BEFORE ORDERING PARTS)
the brodix rock stud girdle is part # BR-6435 and LIST price is about $230 you can get it for less if you shop carefully
BE AWARE that the I.K. 200 heads were shipped with BOTH 3/8" and 7/16" rocker studs ,
and the poly locks for the 7/16" rocker studs ONLY fit that rocker stud girdle
obviously you need to verify what your heads have before you order the matching rocker stud girdle
Verifying your engines clearances, and rocker geometry, and use of A rocker stud girdle and high quality roller rockers go a long way towards maintaining valve train durability

rocker stud girdles require significantly longer shank jam nuts , but you need to mount the rocker stud girdle up out of the way so the upper surface of the rockers can,t touch the lower surface of the stud girdle at full lift
notice the recessed hex on the rocker stud lock nut used with the girdle, cranes roller rockers require a adjustment nut with a .600 diameter , to keep the rocker with its slightly larger slut from deflecting to the side, as the body of the jam nut helps stabilize the rocker , and the nuts are made with matched thread pitch and a stud girdle with the correct stud spacing.
stud girdles significantly strengthen the rocker studs because all 8 studs on a cylinder head resist movement of each individual stud as its subjected to stress as the cam lobe compresses the valve spring and the stud tries to deflect, not just a single stud.... shop carefully and ask lots of questions and its usually a good idea to buy matching components from a single manufacturer if possible for all the valve train components as it tends to avoid mis-matched parts causing clearance or geometry issues.

High Performance Rocker Arms, Valve Springs, Retainers and Locks


By Larry Carley



Upper valvetrain components have more of an effect on power and reliability than you might realize. Most engine builders know that changing the rocker arm ratio increases valve lift for more power. But did you know that changing the rocker arm pivot point can also reduce friction and the rate at which the valves open and close?

On a small block Chevy, altering the rocker arm geometry without changing the rocker arm lift ratio can add 15 to 20 horsepower at the rear wheels.

The stock lift ratio for a small block (SB) Chevy V8 rocker arm is 1.5:1, and for a big block (BB) Chevy V8, the ratio is 1.7:1. Bolt-on aftermarket high lift rocker arms with higher ratios are often used to get more net lift out of an existing cam profile. The most common high lift ratio upgrade for a SB Chevy engine is 1.6:1 rocker arms, and 1.8:1 rockers for BB Chevys. But some performance rockers now offer ratios as high as 2.0:1 or even higher!

Increasing the lift ratio adds horsepower with little or no loss in low rpm torque, idle quality or vacuum. By opening and closing the valves at a faster rate, the engine flows more air for the same number of degrees of valve duration. High lift rocker arms also reduce the amount of lifter travel needed to open the valves, which reduces friction and the inertia of the lifters and pushrods that must be overcome by the valve springs to close the valves. On the other hand, increasing the rocker ratio also increases the effort required to open the valves because of the leverage effect. The higher the rocker arm ratio, the greater the force the camshaft, lifters and pushrods have to exert to push the valves open. But when the valves close, the increased leverage of the rocker arms works the other way making it easier for the springs to shut the valves and push the rocker arms, pushrods and lifters back to their rest positions.

On SB Chevy engines, the stock stud-mounted rocker arms are supposed to be self-centering and self-aligning. The ball pivot inside the stamped steel rocker arm allows the tip of the rocker arm to follow the top of the valve as the valve is pushed open. This creates some back and forth scrubbing friction between the tip of the rocker arm and the top of the valve. And the higher the valve lift and the stiffer the springs, the greater the friction. Over time, this can cause side wear in the valve guides, tip wear on the end of the valve stems, and worn rocker arms.

Aftermarket performance rocker arms, whether they are stamped steel, stainless steel, or diecast, extruded or machined aluminum, usually have a roller tip to reduce friction between the rocker arm and valve. The roller, in theory, rolls back and forth on the top of the valve stem to reduce friction, wear and side forces exerted against the valve. Most stud-mounted aluminum rocker arms also have a needle bearing fulcrum to further reduce friction at the pivot point, and a hardened steel insert in the short end of the arm to accommodate the pushrod. Power gains of 15 to 30 horsepower are often claimed for aftermarket rocker arms even with stock ratios because of reduced friction. Aftermarket performance rocker arms are also stronger than stock stamped steel rocker arms, and provide improved reliability and longevity. But stud-mounted rockers have certain limitations.

One is that they often require pushrod guide plates to help keep everything in proper alignment, especially at high rpms and spring loads. Another limitation is that they can't handle valvetrain misalignment very well. If the rocker arm twists, it may bend the pushrod and/or allow the tip of the rocker arm to walk off the side the valve tip. If that happens, the rocker may push down on the retainer instead of the valve, causing the locks to pop out and the valve to disappear down the guide, destroying the engine.

SHAFT MOUNTED ROCKERS
The hot setup today is shaft-mounted rocker arms. Shaft mounted rockers would seem to be a throwback to the days before the first stud-mounted stamped steel rocker arms appeared on small block Chevy V8s in 1955. One of the features that made the SB Chevy such a performer was its lightweight, high revving valvetrain. But keep in mind, that was a time when maximum engine speeds were in the 6,500 to 7,000 rpm range, not 8,500 to 9,000 rpm or higher, and most engines were running single springs, not double or even triple springs.

Shaft mounted rockers have a number of advantages. One is better alignment. The shaft is rigid so the rockers are held in perfect alignment. This eliminates the need for separate pushrod guide plates while also limiting valve train deflection. At high rpm, pushrods and rocker arm studs can flex quite a bit, and the more they deflect the more it hurts valve lift, duration and valve control. This costs horsepower and can be seen on a dyno. So the more rigid the valvetrain, the less the valve flutter at high rpm. Shaft mounted rocker arms also provide extra strength and support, eliminating the need for a separate stud girdle. Aluminum stud girdles are often necessary to reinforce the valvetrain when a high lift cam (or rockers) and stiff springs are used. The girdle clamps around the studs and ties them together to reduce stud flex and the risk of breakage. But the girdle also makes it harder to adjust the valves. Shaft mounted rocker arms don't have that issue because the adjusters are on the arms, not the studs, and are easily accessible.

Mounting the rocker arms on a rigid shaft also eliminates the "jack hammer" effect that occurs with stud-mounted rockers. Every time the valve opens and closes, the change in valve lash that occurs with a solid lifter cam causes a stud-mounted rocker arm to slide up and down on its stud. This hammering effect can pull a pressed-in stud out of the cylinder head, and may cause fatigue failure in a screw-in stud or the rocker arm.

Another advantage of shaft-mounted rockers is better geometry. By lowering the pivot point of the rockers slightly with respect to the valves and pushrods, the arc that the tip of the arm follows is moved further down the curve. This reduces the back and forth scrubbing on the top of the valve, which reduces friction even more. One supplier of shaft-mounted rockers says this change alone reduces the torque it takes to turn a SB Chevy over by 80 ft. lbs, and is good for 15 to 20 horsepower.

Lubrication can also be an advantage with shaft-mounted rockers. Some have internal oil passages that route pressurized oil directly to the rocker arms and/or valve springs instead of relying on splash lubrication from oil squirting up through the pushrods. Shaft mounted rockers are available from a number of aftermarket suppliers, and fit not only stock SB Chevy and Ford heads but also most of the popular aftermarket heads made by Brodix, World, Edelbrock and others. The shaft-mounted rockers typically sell in the $700 to $900 range and are an excellent upgrade for any performance engine.

Another supplier of aftermarket rocker arms has taken a similar approach by redesigning some of their stud-mounted rocker arms for the LS1 Chevy. The rocker arms require milling the stud pads on the cylinder heads .170" to accommodate the lowered rockers, but the net result is better geometry, less side wear on the valves and faster initial opening that produces more horsepower.

What you may not know is that the actual ratio at which a rocker arm opens a valve is not constant, but varies as the valve opens and closes depending on the arc the arm travels and the position of the rocker pivot point with respect to the top of the valve and the pushrod. The stock LS1 rockers are mounted rather high and initially open the valve at a rate equivalent to about 1.54 to 1 before eventually reaching 1.7:1. The quick lifting aftermarket rocker arms, by comparison, lift the valve off the seat at a ratio that is closer to 1.8 to 1 and then goes to 1.7 to 1 at .200" valve lift. This has the same effect as increasing valve duration about six degrees, and produces 15 to 18 more horsepower.

INTERFERENCE ISSUES
As the ratio of the rocker arms goes up, the net lift of the valves increase and the valve springs are compressed much closer together. Clearances must be checked to avoid coil bind and contact between the bottom of the valve retainer and top of the valve guide. Springs should have a safety margin of .060" of remaining travel at maximum valve lift to avoid coil bind. The minimum clearance between the retainer and valve guide at maximum valve lift should also be .060". If the minimum clearances are not maintained and the valve spring or retainer bottoms out, the valvetrain will usually bend or break a pushrod. Clearance between the rocker arm and spring retainer must also be checked at maximum lift to make sure they don't touch. The stock rockers on a SB Chevy V8 can handle about .470" of valve lift. More lift requires switching to "long slot" rockers or aftermarket rockers with extra clearance.

High lift aftermarket rocker arms or a high lift cam may require using different springs that allow increased spring travel. Some springs cannot handle a maximum valve lift of more than .550". For higher lifts, different springs are required. Follow the spring supplier's recommendations when matching valve springs to maximum valve lift. Another way to avoid spring bind is to raise the installed height of the valve or to lower the spring seat. But both of these will reduce spring tension, which is not the way to go with a high revving engine.

For small block street performance engines with a flat tappet cam and no more than .450" of lift, single springs with 80 to 90 lbs. of seat pressure with the valves closed are usually adequate. For street/strip performance engines, springs with 100 to 120 lbs. of seat pressure are usually recommended. For street hydraulic roller cams, seat pressure should typically be 105 to 140 lbs., and should not exceed a maximum of 150 lbs. with a mechanical roller cam.

Double or even triple springs are usually required to achieve higher spring pressures. Seat pressures for double springs typically range from 130 to 150 lbs. or higher, and 300 or more lbs. for triple springs. Most NASCAR teams run dual springs with seat pressures of 190 to 200 lbs. and open pressures of 500 to 600 lbs. at .750" lift. Pro Stock drag racers, by comparison, typically run triple springs with seat pressures of 375 to 475 lbs. with the valves closed, and up to 1,000 lbs. open!

Increasing spring pressure increases the rpm and horsepower potential of the engine. Every additional 100 rpm may be worth an extra 20 or more horsepower on a highly modified performance motor. The current limit for steel valve springs is about 83 to 85 cycles per second, or about 10,000 rpm. NASCAR teams run a 200 to 400 mile race at 8,500 to 9,000 rpm. But drag racers only run a quarter of a mile.

High pressure valve springs can deliver the rpms, but there's a price to be paid because the springs don't last. Running at such high rpm wears out the springs. Consequently, the springs have to be replaced fairly often (every race with NASCAR engines, and after so many runs with drag racers).

Higher spring pressures also puts more load on the rocker arms, pushrods, lifters and cam lobes, which increases the risk of something breaking.

According to one major camshaft supplier, standard camshafts can usually handle open valve spring pressures of up to 550 lbs. But for higher spring pressures, a carburized 8620 or 9310 steel camshaft is required.

Installing double springs may require the following modifications:

*
* Flycutting the spring seats in the heads to accept the springs.
* Changing the spring retainers to ones that are designed for double or triple springs.
* Changing the valve seals and/or machining the guides for extra clearance.
* Replacing pressed-in rocker arm studs with screw-in studs and a stud girdle, or installing shaft-mounted rocker arms.
* Replacing the stock pushrods with stronger and stiffer 4130 chrome moly pushrods (to prevent pushrod flexing and breakage).
If the springs provide more than 350 lbs. of pressure when the valves are open, the stock stamped steel rockers will have to be replaced with stronger aftermarket steel or aluminum rockers.



BEEHIVE SPRINGS
Beehive springs that taper towards the top are a hot commodity in the aftermarket, but date back to the earliest days of the automobile. Like shaft-mounted rockers, though, they are finding new applications in todays high performance engines. Chevy LS1/LS7 series engines use a factory beehive spring, as do Ford modular 4.6L V8s. Similar spring designs have been developed for SB Chevy and Ford engines by aftermarket suppliers. Unlike a conventional valve spring that has a constant diameter, a beehive spring tapers in toward the top sort of like a real beehive (thus the name). A smaller top means a smaller and lighter valve spring retainer can be used to reduce weight. Also, the change in the diameter of the spring as it tapers toward the top creates a progressive spring rate that helps the spring resist harmonics that occur in conventional constant rate springs. The bottom line is that beehive springs perform better than conventional single springs on many (but not all) engine applications.

One spring supplier said their beehive springs can increase the rpm potential of an engine 100 to 1,200 rpm depending on the cam, valvetrain and other engine modifications. The maximum amount of valve lift a beehive spring can handle is about .650", so if the engine needs more lift it will require dual or triple springs.

Beehive springs have been popular on the street, but some racers are cautious about using them because there's no safety margin if a spring breaks. With a double or triple spring, the engine won't eat a valve if a spring breaks. The extra springs serve as a backup to pull the valve shut.

SPRING COATINGS
Heat is the main enemy of the springs, with dual and triple springs typically generating more heat than single springs because they rub against each other. Managing heat, therefore, is critical for spring longevity.

The durability of a spring depends on the quality and purity of the alloy that is used to manufacture the spring, the heat treatment the spring receives, and any additional surface treatments the spring is given. Some springs are nitrited while others are coated with proprietary chemicals that help the spring run cooler. Another trick that can extend spring life is to have the springs cryogenically treated. Freezing the springs to 300 degrees below zero can increase spring life up to five-fold, according to those who do it.

SPRING INSTALLATION
There are a couple of things to watch when installing valve springs. One is height. This ensures the springs have the required pressure to keep the valves shut. Height is checked by measuring the distance between the spring seat in the head and the retainer on the valve stem. Most performance valve springs are closely matched, but if adjustments are needed it can be done by shimming the valves to equalize pressures. The thicker the shim, the more it increases spring pressure. Don't overshim, though, because doing so may lead to coil bind with a high lift cam or rocker arms.

Shims are made of hardened steel, come in various thicknesses and are usually serrated on one side to prevent rotation (the serrated side faces the head). Some shims are also designed to help insulate the springs from heat generated by the cylinder head. Springs should also be lubricated when they are installed in a new engine, especially double and triple springs, to reduce friction. Soaking the springs in oil or coating them with assembly lube should provide adequate protection during the critical first start-up.

VALVE SPRING RETAINERS & LOCKS
Reducing weight on the valve side of the rocker arm has more of an impact than reducing weight on the pushrod side because of the leverage effect. Lightweight valve retainers made of titanium have long been the preferred upgrade here. But in the past year, the price of titanium has skyrocketed. Most of the world's titanium supply comes from Russia and is being consumed by China. Some aftermarket suppliers have responded to the changing market conditions by introducing new lightweight steel retainers.

For street applications, steel retainers with stock 7 degree locks are usually recommended. But for racing or high rpm roller cams, titanium retainers with 7 or 10 degree locks can reduce weight. Some locks have an extra step inside that reinforces the bottom of the retainer and reduces the risk of the valve pulling through at high rpm. When the valve locks are installed around the valve stem, their edges must not touch each other. They should clamp against the valve stem and hold it securely. Keep in mind that the design of the retainer affects the installed valve height and spring tension.

 

[grumpyvette]

"Hello.

I was going to go Crane all the way including their Gold race rockers 10750-16.

My builder - as did Grumpy before - suggested Comp Cams Ultra Pro Magnum rockers

http://www.superchevy.com/how-to/vemp-0703-corvette-rocker-arms/

This suggestion is for weight saving aspect. I believe both products are top of the line but what sort of weight differences are we talking about here? And does it matter in reality?"

both products are good and your unlikely to see problems with either choice,but its not about weight its about long term durability, steel has a significantly longer expected life span under conditions you'll see on the street and the difference in effective weight as the valve train is effected is minimal as the majority of the weights in the bearings and trunnion, you can run either rocker for years, but in the long term the fact that aluminum fatigues faster will eventually be a factor...it comes down to a compromise, the lighter rocker MIGHT allow you to make a couple more peak hp at the risk of slightly higher chance of an eventual rocker failure, (its generally a good idea to closely inspect all roller rockers every time the valve covers removed) you need to finish a race to win , or be able to depend on the car for transportation, so durability on an engine is more important than the potential of possibly making a couple peak hp on most engines
look, Ive run ERSON, CRANE, CROWER and COMP rockers on my engines, almost interchangeably for years, they all work much better than some of the cheap imports Ive seen,and all of them will last for years if your lube and cooling systems are functioning correctly and you do frequent oil changes, but if durability is the key factor.. I select the CROWER or COMP steel rocker

ERSON ALUMINUM ROLLER ROCKERS
those are some of the most durable aluminum rockers available
Ive had them last in excess of 60K -90k miles on several street sbc I built so they are a quality item
http://www.pbm-erson.com/store.php?catId=24

but Ive had the crower and comp steel rockers still good at 70k 100k plus and still going strong,
obviously the key to durability with any rocker is clean oil, low oil temps and low or moderate spring pressures and the correct valve train geometry
BELOW, STEEL ROCKERS

and this Comp Cams

these three rockers above are steel

pictured above you see the last rocked badly out of alignment with the valve center line,
a good example why you need adjustable guide plates, this rocker if left too run off center like this, on the valve stem tip , will quickly destroy the valve guide and rocker

small block chevy adjustable push rod guide plate

BBC ADJUSTABLE PUSH ROD GUIDE PLATE


its rather common to have push rods rub or bind when swapping to the higher ratio 1.6:1 rockers so its mandatory you carefully check EVERY one through its full arc for proper clearance and use a louis tool to extend the push rod guide holes is thats required
this is mostly a matter of carefully checking clearances and verifying valve train
geometry,and use of quality parts rather than selecting the cheapest crap available, in many cases the simple swap of components can be done with few issues ,BUT its rather common for parts too bolt in, but not fit correctly, but LESS-experienced mechanics don,t see the indications of potential trouble,and wonder why parts failed later as a result!
parts that rub or bind and were thought too be correctly functioning only to be found later too be causing rapid wear or even a cam or lifter failure as a result of the parts installer, NOT verifying the correct clearances and geometry, so take your time and read the links and check, never assume a darn thing, fits correctly until you verify the clearances over the full range of movement.
read thru the links and sub links they may open your eyes


youll want too use a .060 clearance too the push rod to cylinder head slot clearance CHECKED CAREFULLY OVER THE FULL ARC OF THE ROCKER TRAVEL FOR A FULL TWO ENGINE ROTATIONS
if you need a LOUIS TOOL to lengthen the slots in the cylinder head I generally lay a section of plastic wrap in the lifter gallery and be sure to place two magnets on the blocks lifter gallery wall, to hold the thin plastic wrap in place firmly, below the cylinder head while drilling to catch the metalic debris the drill will generally produce, between the plastic sheat and the magnets youll generally catch 100% of the trash the drill generates

http://www.magnet4less.com/product_info.php?cPath=3_27&products_id=254

obviously having adjustable push rod guide plates to center the rockers on the valve stems and push rods in the cylinder head slots is almost mandatory.
as is verifying all rocker geometry and valve train clearance issues

http://www.summitracing.com/search/...d-length-checkers?autoview=SKU&ibanner=SREPD5
Proform Pushrod Length Checkers 66789 SBC 3/8" rocker studs

Proform Pushrod Length Checkers 66790 SBC 7/16" rocker studs

Proform Pushrod Length Checkers 66806 BBC 7/16" rocker studs

viewtopic.php?f=52&t=126&hilit=louis+tool

https://www.hotrod.com/articles/roller-rocker-ratio-test/

https://www.onallcylinders.com/2018...rease-horsepower-engine-masters-gets-answers/

https://www.hotrod.com/articles/hrdp-1305-rocker-arm-comparo/


http://garage.grumpysperformance.com/index.php?threads/upgrade-choices.11416/#post-52423

http://garage.grumpysperformance.co...e-used-prw-stainless-steel-rocker-arms.14896/

thinking about putting roller rockers on my 327.

IM seriously considering/ thinking about putting roller rockers on my 327.do i have room to put 1.6 ratio or just stay with 1.5s http://garage.grumpysperformance.com/index.php?threads/louis-tool-swapping-to-1-6-1-ratio-rockers.14761/...

garage.grumpysperformance.com

viewtopic.php?f=52&t=528&p=45493&hilit=+long+slot#p45493

https://www.chevyhardcore.com/tech-...zing-your-cams-potential-with-better-rockers/

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/#post-54088

thinking about putting roller rockers on my 327.

IM seriously considering/ thinking about putting roller rockers on my 327.do i have room to put 1.6 ratio or just stay with 1.5s http://garage.grumpysperformance.com/index.php?threads/louis-tool-swapping-to-1-6-1-ratio-rockers.14761/...

garage.grumpysperformance.com

http://garage.grumpysperformance.co...-rockers-and-the-pushrods-rub.198/#post-46839

http://garage.grumpysperformance.co...all-block-chevy-guide-plates.2839/#post-12739

http://garage.grumpysperformance.co...-rockers-and-the-pushrods-rub.198/#post-46839

 

[87vette81big]

I read late last night Grumpy.
Good info.
Gave it a bump. 4 years later.

 

[Strictly Attitude]

read this before I was a member here when I was doing research on my roller rockers