press in vs threaded rocker studs

grumpyvette

Administrator
Staff member
press in studs work fine on stock cams because the stock cams valve spring loads are low, in most cases the stock springs have load rates in the 110-130lbs seat and 300-320 lbs fully depressed range,
keep in mind stock cams rarely get close to the fully depressed lift range so average peak loads are lower.
if the open valve spring pressure exceeds about 320lbs, or engine rpms regularly exceed 6000rpm or the valve lift exceeds .475,
Id suggest screw in rocker studs should increase durability.
you can run EITHER push rod guide plates OR self aligning rocker arms but NOT BOTH. keep in mind guide plates REQUIRE screw in rocker studs and rocker stud bosses that are machined to match guide plates
It may surprise many people but even many corvettes came with pressed in rocker studs, the fastest way to visually verify is to look for the hex stud base thats used to screw them in, if theres no hex base chances are excellent that they are press in studs.
screwstud.jpg

cyl7.jpg

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

for several years even stock BBC engines ,(the markVI and mark V) as opposed to the (mark IV earlier BBC engines)
also don,t use adjustable rocker arms,
if your running a stock cam and valve train with stock O.E.M. heads you probably can get by without them,
swap to a higher lift cam and a longer duration and aftermarket heads and better valve strings and in my opinion,
you would be very foolish to build and use a performance BBC engine without adjustable push rod guide plates
what you really should do is order these
Dart 27001230-4 - Dart Pushrod Guideplates

301-27001230-4.jpg



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

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
rockertrunion1.png

rollflata.jpg


READ THIS THREAD
viewtopic.php?f=87&t=10976
sguide_plate.jpg


STUD-02.jpg

typical pressed studs
IMG_0569.jpg

20024s.jpg

http://www.mcmaster.com/#thread-forming-taps/=ke38k5
http://www.mcmaster.com/#standard-taps/=ke36u2
Photo0020.jpg


rockeroilfeed.jpg

longslotz.jpg

check all valve train geometry and clearance on any engine you assemble or modify the valve train on.
bbcvtq5.jpg

bbcvtq6.jpg


long slot rockers are far less likely to bind on rocker studs

STUD GIRDLES ADD A GREAT DEAL OF RIGIDITY TO THE VALVE TRAIN
pressedstud.jpg

typical factory pressed in rocker studs
IMG_0568.jpg

it should be obvious that the slot clearance in some rockers , especially with poly locks significantly limits rocker movement before clearances become an issue
hrdp_0412_06_z+big_block_chevy_engine+rocker_arms.jpg

80063.jpg


rockerstudp1t.jpg

rockerstudp2.jpg


it should be noted that if the rocker stud protrudes into the port it should be trimmed to the port roof as any threads sticking down into the runner disrupt flow and don,t supply extra support to the rocker stud,and stud threads should use loc-tite tread sealant
BEEHIVE SPRINGS and FORGED STEEL ROCKERS GIVE A GOOD DEAL MORE ROCKER TO RETAINER CLEARANCE
rockertoretainer.jpg



STUD-18.jpg

screw in rocker studs
http://www.maxchevy.com/tech/2007/ii_12-stud-1.html

step one
use a thread cleaning tap to chase the threads
(assuming your using push-rod guide plates and you've had the rocker stud bosses spot faced square naturally)
(YOU MAY WANT TO READ THESE THREADS)
viewtopic.php?f=27&t=1262&p=6142&hilit=taps+dies#p6142

viewtopic.php?f=50&t=1222

step two
verify the threads in the head are deep enough so the lower stud end won,t bottom out, ESPECIALLY if your not using push rod guide plates and are using self aligning rockers, because the studs screw deeper without the push-rod guide plates acting as a spacer washer

step three
degrease and dry the threads with solvent and high pressure air

step 4
install studs thru push-rod guide plates after you've degrease the threads and added a couple drops of LOC-TITE
tighten only until the lower mid shank hex you use to tighten the rocker stud, stop when they start to bear on the guide plates, and verify push-rod clearance and rocker geometry, only when thats verified correct tighten with a torque wrench to spec. torque.

step 5
whack each stud with a plastic mallet like your driving a nail, and re-torque to verify the studs correctly compressing the push-rod guide /alignment plates

screw in studs are mechanically locked into the heads with a thread and will easily hold far greater loads, as a general rule if you want to exceed .500 lift or 6000rpm with your valve train on a SBC its a good idea to upgrade to screw in thread style rocker studs, rather than the press in stock versions.
press in rocker studs generally don,t use push rod guide plates and in many cases even stock valves springs can eventually cause them to pull out and change your clearances if the engine frequently operated at high rpms and load rates with a slightly higher lift aftermarket cam that exerts more than the designed spring loads on the studs.
upgrading to threaded studs is not all that difficult, but if your not at least semi-experienced with minor machine work ID strongly suggest having a local machine shop do the work because getting the angle and depth of the stud holes threaded correctly and machining the top of the stud boss on each location dead on square to mount the guide plates correctly is not as simple as it first might appear.
ID suggest swapping to screw in rocker studs when you exceed 220 duration or .480 lift,expect to exceed 6000rpm, or swap to springs with over 300lb open pressure

KEEP IN MIND, MANY PEOPLE THAT HAVE BROKEN ROCKER STUDS HAVE FAILED TO VERIFY THE PISTON TO VALVE, CLEARANCES, ROCKER STUD TO ROCKER SLOT CLEARANCES,AND SPRING BIND CLEARANCES, etc.

read thru the links and sub-links as theres valuable info you'll need later


MOST PEOPLE WOULD THINK...this is a machine shop only thing to do.

first there a few things you need to do the procedure
small drill press, because a free held drill will not maintain the exact angle
stud puller and guide 21.00
stud boss cutter 55.00
cutting oil 6.00
7/16 x 14 taps 8.00
screw in studs 25.00
guide plates 20.00

http://www.tooldiscounter.com/ItemDispl ... =POW351360

http://teamc.com/i-4566671-competition- ... utter.html

these are the places you can get these tools , and info on upgrading the studs
powerhouse products
http://www.compperformancegroupstores.c ... re_Code=PH

http://www.goodson.com/

http://www.jegs.com/i/Comp+Cams/249/5306/10002/-1

http://www.jegs.com/i/Milodon/697/84327/10002/-1

http://performanceparts.com/part.php?partID=184869
http://www.summitracing.com/parts/SUM-G1675/?rtype=10
sum-g1675_w.jpg


viewtopic.php?f=52&t=689&p=956#p956

http://www.2quicknovas.com/vortecheads.html

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

http://books.google.com/books?id=G2kUib ... ds&f=false

viewtopic.php?f=52&t=181

viewtopic.php?f=52&t=181&p=215#p215

http://www.iskycams.com/pdfcatalog/2004-05/page38.pdf

http://www.arp-bolts.com/Catalog/Catalog.html

http://www.summitracing.com/parts/NAL-1 ... /?rtype=10

viewtopic.php?f=52&t=2875

rockerguide.jpg




guide plates and screw in studs
keep in mind that you can use EITHER self aligning rockers OR guide plates BUT NOT BOTH at the SAME TIME with properly installed screw in rocker studs

self aligning rockers have ridges to prevent the rocker from moving off the valve stem

anyone who has extensive engine assembly experience will have at some point had an experience related to a failed valve train component, and ID bet the vast majority of the guys who had a cam or lifter or rocker arm , valve spring,
component fail, were certain to blame the failure on a defective component,
when the truth is that in many cases the person installing that component failed to carefully check clearances, check the valve train geometry or provide the correct lubrication, or follow the manufacturers installation instructions.
yeah I've had guys ask for help when their muscle car or corvette engines had serious issues, and I've done more than my share of screwed up engine autopsies, guys install a cam, never checking the valve train clearances , and invariably, so & so brand cam SUCKS because it failed .... the fact the guy never checked for coil bind, rocker to rocker stud clearances or piston to valve clearance or even ever applied moly lube or has a clue how to properly adjust valves and has never seen a degree wheel, has zero to do with the component failure????
yeah, so & so brand cam SUCKS because it failed
I have got to point out , that in my experience , its far more likely that the part was not properly installed and clearances were never properly checked, I've had guys tell me they bent several push rods, or busted valve springs...but it never occurred to them that there must be a reason ...and checking clearances or using a degree wheel and dial indicator....NAAAAA, thats not required
hell you just line up the dots and your good to go!!!
yeah the valve trains stock, the orriginal valve lift is .450 , and the new cams lift is .615, but thats only a change of a little over 1/6th" what could go wrong???
read these links
http://garage.grumpysperformance.com/index.php?threads/cam-wear-articles-you-need-to-read.282/
http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/
http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/
http://garage.grumpysperformance.co...ectly-and-get-it-to-last-cam-install-info.90/
http://garage.grumpysperformance.com/index.php?threads/checking-piston-to-valve-clearances.399/
http://garage.grumpysperformance.co...tched-valve-spring-required.13774/#post-77425
http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/
COC1318-1.jpg


p177897_image_large.jpg

0607phr_31_z+camshaft_basics+valve_springs.jpg
 
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grumpyvette

Administrator
Staff member
praza said:
I have a problem with my 87 caprice. I torn apart the engine, and IMHO I found something unusual. The side aligment of rocker arms have a huge side allowance. The rocker arms are moving from side to side, even using just using just pushrods, although they were adjusted. One side of the engine is better then other.

I feel the new rocker arm kit is a solution, but what could cause this behavior and what allows it?

Please check videos below
praza said:


that problem, and its cause, and the solutions, all so obvious its comical.

rockersstock6.jpg

IF your cylinder heads are not precisely drilled to act like push rod guide plates like these heads pictured above are ...



MOST head castings are NOT machined like that and require either push rod guide plates or self aligning rockers.
stock chevy stamped rockers come in two basic versions,in the videos above the heads are installed without push rod guide plates OR self aligning rockers, you must use one or the other method to maintain rocker alignment
rockers must EITHER use PUSH ROD GUIDE PLATES, that keep the push rods aligned with the rocker stud and valve tip,like these two pictures
rockersGP004.jpg

rockerguide.jpg

rockersGP003.jpg

OR you use SELF ALIGNING ROCKERS
self aligning rockers have ridges stamped in the tip that prevent the rocker from moving off the valve stem alignment center line to prevent the rocker from moving off the valve stem




rockersGP002.jpg


longslotz.jpg


rockers and rocker studs rarely if ever break for no reason, theres almost always without exception, a clearance or geometry issue, thats the cause,it requires hundreds of lbs of force, to snap off a rocker stud, and thats almost always the result of a clearance issue like spring bind or rock slot to rocker stud clearance being too tight or the rocker/valve train geometry being wrong., just because some component rotates without binding up , does not mean its going to function at higher rpms and loads
if you have not verified all the clearance issues Id strongly suggest you look into that.
keep in mind that the stress levels tend to increase along with higher valve spring load rates and increased rpm levels
and the stock valve train design will not function for long under spring load rates and increased rpms unless better quality components and increased cooling from more oil flow are used, once the spring load rates increase more than about 50% over the stock load rates you better be using a stud girdle


theres related info in these threads thats well worth the time to read

viewtopic.php?f=52&t=4680

viewtopic.php?f=52&t=181

viewtopic.php?f=52&t=1376

viewtopic.php?f=52&t=528

viewtopic.php?f=52&t=4680&p=12650#p12650

viewtopic.php?f=52&t=3009&p=8361&hilit=girdle#p8361

viewtopic.php?f=52&t=1005

viewtopic.php?f=52&t=399

http://www.maxchevy.com/tech/2007/ii_12-stud-1.html

IM always amazed at the guys that think swapping from 3/8" to 7/16" rocker studs is going to be a huge improvement,in valve train stability,now theres not the slightest doubt that an increase of about 18% in cross sectional area on the studs a significant increase in strength, and while that helps, its not the huge improvement many people think it is because its generally not the rocker studs that fail from flexing,unless they are defective, as most would have you believe, but because its the rocker geometry and rocker support not the stud diameter, that matters, more, you can,t expect a rocker stud with one end unsupported to have any where near the resistance to deflection that a rocker stud with BOTH ends supported will have.
if you support both ends of the rocker studs you easily increase the load bearing capacity to far more than the additional stud diameter increase, can ever do,having one end unsupported the stud acts a bit like a nail being pulled by a hammer, in that loads applied to the upper end tend to both bend the nail and pull on the lower end thats where the use of STUD GIRDLES comes into play.
simply supporting the rocker stud tips so that the forces acting on a single rocker stud are now opposed by the resistance to deflection of all 8 rocker studs
is a huge improvement

revkit1.jpg

revekit.jpg

on many hydraulic roller lifter applications a REV KIT on hydraulic roller lifters adds several hundred RPM to the power band before valve control issues develop
IMG_2071.jpg

http://www.summitracing.com/parts/SUM-141010/?rtype=10

555-20518.jpg


https://www.jegs.com/i/JEGS/555/20518/10002/-1
sum-141010.jpg

http://www.summitracing.com/parts/CCA-4014/
caa-4014.jpg

wrl-832010_w.jpg


viewtopic.php?f=52&t=1769

Photo0020.jpg

http://www.summitracing.com/parts/BRO-BR1230/?rtype=10
br1230_w.jpg


STUD GIRDLES ADD A GREAT DEAL OF RIGIDITY TO THE VALVE TRAIN

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/#post-54232
rpo1x.JPG

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

beehivesprcl.jpg

retain6.jpg

fact
valve train components RARELY just break for no reason

Fact
it takes hundreds of pounds of force to bend push-rods

Fact
IMPROPER CLEARANCES can destroy a valve train or cam in under 30 seconds

Fact
the most common REASON is INCORRECT CLEARANCE OR ROCKER GEOMETRY, or failure to adjust valves properly

FACT
reading links and sub-links helps you isolate the cause, of a failure,... carefully reading through will allow you to avoid having the problem

Fact
In most cases its operator error , or failure to correctly set-up and clearance the valve train that causes problems

Fact
20 minutes -to a couple hours well spent asking questions, and being damn sure you understand the answers, can save you weeks of repairs and machine shop bills

Fact
NO ONE does this the first few times without making SOME mistakes


Fact
having an experienced mentor help guide you through the process tends to reduce the chances of failure

Fact
joining several local corvette or muscle car clubs and helping the older more experienced members work on their cars, and letting them help you on yours, speeds the learning curve


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

http://garage.grumpysperformance.com/index.php?threads/adjusting-valves.196/

http://garage.grumpysperformance.co...ear-articles-you-need-to-read.282/#post-52017

http://garage.grumpysperformance.co...1-6-1-ratio-rockers-and-the-pushrods-rub.198/

http://garage.grumpysperformance.co...lve-springs-loads-and-installed-height.10709/

http://garage.grumpysperformance.co...caused-hydraulic-lifters-to-come-apart.10482/


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/
 
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grumpyvette

Administrator
Staff member
HEY GRUMPY??
"As far as checking rocker to stud clearance, how would you do that other than just rolling it over and watching. I don't see any marking to indicate that this was the problem, but at the same time, can not rule out that at 7000 rpm, these things are not flinging around more than at 50 rpm when I am looking at it."

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
the quick easy route is to take a bit of uninsulated 12 ga solid core copper wire and make a (U) shape,with about 4" legs , you then bend the ends into a (J)at 90 degrees to the (U)the ends are placed (hooked into)in the rocker slot from the lower side of the rocker between the stud and rocker slot and the engines spun manually by a friend while you hold the wire in the rocker for two full rotations, if the wires not pinched your good, check the next rocker, if it gets crimped you need to lengthen the rocker slot
rollerrocker.jpg


theres hundreds of ways to destroy an engine, but a common route is trying to compress solid objects in the combustion chamber,where theres not nearly enough clearance,
rockerh1.png

rockerh2.png


rockerbin.jpg

rockertrunion1.png


failure to keep the pistons from hitting the valves, bending valves, ,over reveing the valve train and having un-controlled valve movement, or having chunks of piston,that detonation can break loose, being compressed against the heads,can result in the cracked cylinders, and bent rods like the pictures below show
crackedbore.jpg

crackedbore1.jpg

bustedvalve.jpg

blockcrack.jpg

brokemaincap.jpg



IT takes hundreds of pounds of force to snap push rods, if your bending push-rods,somethings binding or hitting someplace whether you want to admit it or not, step back and find out whats wrong!
theres a dozen potential sources for clearance issues so check out the links and verify the valve train clearances and geometry

valvetrain1.gif

seal4.jpg

irc_figure5.gif

irc_figure5a.gif

lifterpreload.gif


if you didn,t verify the cam timing with a degree wheel , you failed to adjust the valve preload, or lash,and you failed to check clearances, like rocker arm slot to rocker stud and push rod to guide plate or push rod to cylinder head during the whole 720 degree valve train cycle, and clearances like piston to valve and spring bind and retainer to valve guide your going to have issues in most cases, its best to assume you did EVERYTHING WRONG until you verify ALL the potential clearance and geometry issues
your in miss. so your not local, but it won,t take long to isolate the cause if you do it check the potential sources, just assume everything needs to be verified before proceeding

viewtopic.php?f=52&t=181

viewtopic.php?f=52&t=90

viewtopic.php?f=52&t=399

http://www.crustyquinns.com/tech/easyout.html
 
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grumpyvette

Administrator
Staff member
STUD-02.jpg


press in rocker studs (like those pictured above) have the annoying habit of slowly and unpredictably coming loose over time if you install valve springs with much over about 350 lbs rated open lift, pinning the studs usually results in a cracked head or busted rocker stub over time, so the smart way to prepare the heads is screw in rocker studs, this is one reason every shop should on a decent drill press or mill, most local machine shops charger between 4100-$125 plus parts in some cases for this job and most experienced mechanics can do it in less than an hour
http://www.jegs.com/i/ARP/070/134-7124/ ... tId=744892
720-1074.jpg

https://www.jegs.com/p/ARP/ARP-Rocker-Arm-Studs/744892/10002/-1

guidepla.jpg



its very common to find you'll gain a couple horsepower with the addition of a rocker stud girdle employed,

as youll have both more precise valve train control and less deflection, Ive seen guys instantly gain an extra 150 rpm-200 rpm,
before they started feeling valve float or loss of valve train control and its certainly less stress on the cylinder head casting and rocker studs.
the one thing ID suggest is that before you buy any rocker stud girdle you ask questions, many cylinder head designs use non-standard rocker stud spacing.

you need EITHER PUSH ROD GUIDE PLATES

BELOW NOTICE SCREW IN ROCKER STUDS
rockerguide.jpg

80063.jpg


rockerstudp1t.jpg

OR SELF ALIGNING ROCKERS (BELOW)
USED WITH PRESS IN ROCKER STUDS

rockersGP002.jpg

stamprockf.jpg

used with press in rocker studs
pressedstud.jpg

rockersGP009.jpg

yes they DO MAKE ROLLER ROCKERS IN BOTH STANDARD AND SELF ALIGNING VERSIONS
longslotz.jpg


if your heads have push rod guide plates you are not supposed to use self aligning rockers as yes they will frequently bind the push rods up and keep them from spinning, if you have guide plates you want the NON-self aligning rockers
as I've pointed out dozens of times a day spent reading links will save you a week of work and a wheelbarrow full of wasted cash.

http://garage.grumpysperformance.co...s-in-vs-threaded-rocker-studs.2746/#post-7475

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

http://garage.grumpysperformance.co...-in-vs-threaded-rocker-studs.2746/#post-43539

http://garage.grumpysperformance.com/index.php?threads/push-rods-rub.13031/#post-67779

http://garage.grumpysperformance.co...-rockers-and-the-pushrods-rub.198/#post-56571

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

http://garage.grumpysperformance.co...-pushrods-and-check-info-you-might-need.5931/

http://garage.grumpysperformance.com/index.php?threads/stock-gm-push-rod-length.3844/

http://garage.grumpysperformance.co...ve-spring-iinstalled-height.12790/#post-66037

http://garage.grumpysperformance.com/index.php?threads/more-bent-push-rods.12401/#post-61890

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/#post-54088
SUM-900136_ml.jpg

http://www.summitracing.com/parts/sum-900136
http://www.goodson.com/Rocker-Arm-Stud-Conversion-Kit/
S-450-KIT.jpg

bolthread.png


http://www.tooldiscounter.com/ItemDispl ... =POW351360
IF you have a decent drill press or mill this jobs hardly difficult

g7946_det1.jpg

its not horsepower, its the stress on the valve train, that makes a rocker stud girdle and its increased rigidity useful,
and thats more closely related to average stress levels, RPM and VALVE SPRING LOAD RATES
any time your occasionally exceeding 6000rpm or getting close too 330 lbs of open valve load rate Id strongly suggest screw in rocker studs
any time your intentionally exceeding 6000rpm and exceeding 350 lbs of open valve spring rate a rocker stud girdle might be a good idea.
and
scp390.jpg


shaft rockers add rigidity , to the valve train,by eliminating the rocker stud flex issues,
but keep in mind that a rocker stud girdle can be added to the stock type of valve train,
and when used with quality roller rockers they add a good bit of rigidity to the stock style valve train.
short answer, as a rule of thumb,shaft rockers are advisable

(1) any time your valve open loads exceed 400 lbs and/or you want to exceed 6500 rpm regularly.
(2) any time you intend to exceed 7000 rpm regularly and valve open loads exceed 500 lbs they would be considered almost mandatory..
yes you can in most cases use a stud girdle, with quality roller rockers,
but the shaft rocker design tends to be more rigid, and tends to aid durability


rocknut.png

RELATED THREADS
http://garage.grumpysperformance.co...-rockers-vs-rocker-stud-girdles.663/#post-911

http://garage.grumpysperformance.co...-in-vs-threaded-rocker-studs.2746/#post-43539

http://garage.grumpysperformance.co...ich-is-best-steel-or-aluminum.3124/#post-9141

http://garage.grumpysperformance.com/index.php?threads/roller-rockers.3009/#post-8361

http://garage.grumpysperformance.com/index.php?threads/locating-the-source-of-that-noise.15694/

http://garage.grumpysperformance.com/index.php?threads/cam-lobe-aceleration-rates.2627/#post-8341

http://garage.grumpysperformance.co...and-setting-up-the-valve-train.181/#post-1192

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

http://garage.grumpysperformance.co...er-tip-vs-full-roller-rockers.2875/#post-7458

http://garage.grumpysperformance.co...-pushrods-and-check-info-you-might-need.5931/

http://garage.grumpysperformance.co...n-v-vi-to-adjustable-rockers.4564/#post-12170
http://www.summitracing.com/parts/pro-66950

http://www.summitracing.com/parts/sum-141010
many factory heads came with pressed in rocker studs, these won,t work with push rod guide plates and tend to pull out under high spring load rates, so the heads are machined for screw in rocker studs and in many cases matching push rod guide plates

STUD-02.jpg


screwtap1.jpg

studs can be pulled with a stack of washers and a rocker nut used on the threads
screwtap2.jpg

after pulling the press in style rocker studs most machine shops will spot face mill the rocker stud area around the hole down about -3/8" to provide a true flat 90 degree angle surface for the push rod guide plates to be clamped firmly on by the screw in rocker studs , the materials removed to keep the rocker stud height with the guide plates installed correct, and provide extra support for the rocker stud shoulder hex
RockerMillingSpecs.jpg

screwtap3.jpg

screwst2.png

usually the heads stud area is machined flat at 90 degrees to the rocker stud center line, for guide plate clearance before the holes drilled and threaded
screwtap4.jpg

screwtap5.jpg

several places sell these alignment fixtures to insure the rocker stud alignment for both drilling and tapping and threads are consistently lined up
screwtap6.jpg

screwtap7.jpg

screwtap8.jpg

screwtap9.jpg

screwtap10.jpg

rockerguide.jpg

done correctly with the heads machined, guide plates and thread locker on the rocker studs
CC-Split-Mod-Phase-4-40.jpg

keep in mind the cam lobe ramp acceleration and valve spring load rates.
as any decent mechanic will tell you, you need to finish a race to win it and having a car that constantly breaks parts won,t be fun, and gets darn expensive very rapidly
if your valve train won,t remain stable and under control consistently and handle the stress at the cams intended max rpm, (plus a bit more) your almost sure to have low durability, lots of valve train wear and parts breakage!
lets say your comparing two similar cam,s with listed specs
ones got 215 duration with .450 lift,
the others got 215 duration with 510 lift
Id bet 90% of the guys reading that figure.....hey I get more lift with the second cam, thats obviously going to improve air flow & potential power, so thats the route to take....WRONG!!!

with flat tappet cams, if you exceed a certain lobe acceleration angle you tend to develop valve control and wear issues rather rapidly , mostly because the valve spring load rate required to maintain lifter to cam lobe contact at higher rpm ranges, potentially causes extremely high contact pressures between the two moving surfaces.

SPEND $10 and get a calculator ,in this hobby its a darn useful tool

ticalcx1.jpg

http://www.walmart.com/ip/Texas-Instruments-TI-30X-IIS-Scientific-Calculator/1535939


Isky claims that the Comp XE cams violate the 47.5% rule. The 47.5% rule applies to flat tappet cams for SBCs with 1.5 rockers but the concept is still the same for other configurations where the designs are "on the edge" or "over the edge" for lobe intensity. For 1.5 ratio SBCs, the duration at .50 must exceed 47.5% of the total valve lift or your asking valve train problems. For example, take a Comp Cams Magnum 280H, with 230 duration and, 480 lift...230/.480 = 47.9% which exceeds 47.5% therefore would not pose a threat to components. We do not regularly hear about the older, safer HE and Magnum designs rounding off lobes anywhere near as often as the XE cam designs. Unfortunately, some of the Comp Cams XE dual pattern lobes break this 47.5% rule on the intake side so they are likely to be problematic. The design has "steeper" ramps that are too quick for durability and reliability according to other cam manufacturers. They will wipe lobes in a heart beat especially if you have not followed the proper break-in procedure. Other designs are more forgiving during break-in and less likely to fail.
ones got 215 duration with .450 lift,215/450=.47.7%
the others got 215 duration with 510 lift/215/500=43%


one factor I will mention is that each manufacturer tends to look at durability, ramp speeds and max lifter acceleration very differently, one reason I tend to prefer CRANE & CROWER is that they both company's in general realize the engine must finish the race to win and a busted valve train is a HUGE problem,they both realize, and design valve train components and cam lobes with DURABILITY and reliable valve control as top priority,s that are far more important than squeezing every possible potential HP from a cam lobe design at the expense of long term durability
http://garage.grumpysperformance.com/index.php?threads/cam-lobe-aceleration-rates.2627/#post-6777

http://garage.grumpysperformance.co...s-on-valve-spring-pressures.10268/#post-41364

http://garage.grumpysperformance.co...-rocker-ratio-help-your-combo.2632/#post-6790

http://garage.grumpysperformance.co...-calculators-and-basic-math.10705/#post-46737
summit racing , ARP , MR GASKET all sell the correct threaded rocker studs in both 3/8" or 7/16" threads, obviously the guide plates and roller rockers etc. must be correctly sized to match the stud size
http://www.summitracing.com/parts/sum-g1675
SUM-G1675.jpg



THERE ARE SCREW IN ROCKER STUDS DESIGNED TO BE USED WITHOUT GUIDE PLATES

Id suggest you avoid them as they can and frequently do cause head damage if over tightened
as the pictures below show

http://www.summitracing.com/parts/mrg-1076
mrg-1076_w.jpg

PhotoApr10_90119PM.jpg

PhotoApr10_90751PM.jpg


g7946_det1.jpg


61SBjMHefiL._SL1200_.jpg

every drill press needs a decent vise
3_angle_vise.jpg
3_angle_vise.jpg


http://store.summitracing.com/partdetail.asp?part=TFS-30400700&autoview=sku

http://store.summitracing.com/partdetail.asp?part=TFS-30400701&autoview=sku

its very common to find you'll gain a couple horsepower with the addition of a rocker stud girdle employed,
as youll have both more precise valve train control and less deflection, Ive seen guys instantly gain an extra 150 rpm-200 rpm,
before they started feeling valve float or loss of valve train control and its certainly less stress on the cylinder head casting and rocker studs.
the one thing ID suggest is that before you buy any rocker stud girdle you ask questions, many cylinder head designs use non-standard rocker stud spacing.




girdle9.jpg


IMG_2071.jpg

tfs-30400701_w.jpg

its not horsepower, its the stress on the valve train, that makes a rocker stud girdle and its increased rigidity useful,
20024s.jpg


Photo0020.jpg

P1010018-2.jpg
 
Last edited by a moderator:

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
if youve ever wondered why the press in rocker studs work loose and pull out of heads,
or why some less expensive rocker studs break, keep in mind the rocker and push rods,
are under hundreds of ft lbs of valve spring pressure and the rocker studs deflect significantly under load,
as the lifter rides up on the cam lobe and the valve spring deflects under load,
its really a miracle more rockers and rocker studs don,t snap off.
and the video, shows clearly why rocker stud girdles add considerable valve train stability




https://www.summitracing.com/parts/cca-4729/overview/


https://www.summitracing.com/search...ywordMatch&SortOrder=Ascending&ibanner=SREPD1

anyone who has extensive engine assembly experience will have at some point had an experience related to a failed valve train component, and ID bet the vast majority of the guys who had a cam or lifter or rocker arm , valve spring,
component fail, were certain to blame the failure on a defective component,
when the truth is that in many cases the person installing that component failed to carefully check clearances, check the valve train geometry or provide the correct lubrication, or follow the manufacturers installation instructions.
yeah I've had guys ask for help when their muscle car or corvette engines had serious issues, and I've done more than my share of screwed up engine autopsies, guys install a cam, never checking the valve train clearances , and invariably, so & so brand cam SUCKS because it failed .... the fact the guy never checked for coil bind, rocker to rocker stud clearances or piston to valve clearance or even ever applied moly lube or has a clue how to properly adjust valves and has never seen a degree wheel, has zero to do with the component failure????
yeah, so & so brand cam SUCKS because it failed
I have got to point out , that in my experience , its far more likely that the part was not properly installed and clearances were never properly checked, I've had guys tell me they bent several push rods, or busted valve springs...but it never occurred to them that there must be a reason ...and checking clearances or using a degree wheel and dial indicator....NAAAAA, thats not required
hell you just line up the dots and your good to go!!!
yeah the valve trains stock, the orriginal valve lift is .450 , and the new cams lift is .615, but thats only a change of a little over 1/6th" what could go wrong???
read these links
http://garage.grumpysperformance.com/index.php?threads/cam-wear-articles-you-need-to-read.282/
http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/
http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/
http://garage.grumpysperformance.co...ectly-and-get-it-to-last-cam-install-info.90/
http://garage.grumpysperformance.com/index.php?threads/checking-piston-to-valve-clearances.399/
http://garage.grumpysperformance.co...tched-valve-spring-required.13774/#post-77425
http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/
 
Last edited:

Maniacmechanic1

solid fixture here in the forum
Isky claims that the Comp XE cams violate the 47.5% rule. The 47.5% rule applies to flat tappet cams for SBCs with 1.5 rockers but the concept is still the same for other configurations where the designs are "on the edge" or "over the edge" for lobe intensity. For 1.5 ratio SBCs, the duration at .50 must exceed 47.5% of the total valve lift or your asking valve train problems. For example, take a Comp Cams Magnum 280H, with 230 duration and, 480 lift...230/.480 = 47.9% which exceeds 47.5% therefore would not pose a threat to components. We do not regularly hear about the older, safer HE and Magnum designs rounding off lobes anywhere near as often as the XE cam designs. Unfortunately, some of the Comp Cams XE dual pattern lobes break this 47.5% rule on the intake side so they are likely to be problematic. The design has "steeper" ramps that are too quick for durability and reliability according to other cam manufacturers. They will wipe lobes in a heart beat especially if you have not followed the proper break-in procedure. Other designs are more forgiving during break-in and less likely to fail.
ones got 215 duration with .450 lift,215/450=.47.7%
the others got 215 duration with 510 lift/215/500=43%


one factor I will mention is that each manufacturer tends to look at durability, ramp speeds and max lifter acceleration very differently, one reason I tend to prefer CRANE & CROWER is that they both company's in general realize the engine must finish the race to win and a busted valve train is a HUGE problem,they both realize, and design valve train components and cam lobes with DURABILITY and reliable valve control as top priority,s that are far more important than squeezing every possible potential HP from a cam lobe design at the expense of long term durability

I had all but forgotten about the 47.5% Rule Grumpy.
CC Hi Tech Race cam I used years ago has 47.2 %.
Isky last used and using again has 43.9 %.
 
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