press in vs threaded rocker studs



press in vs threaded rocker studs

Postby grumpyvette » January 16th, 2010, 11:45 am

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



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typical pressed studs
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http://www.mcmaster.com/#thread-forming-taps/=ke38k5
http://www.mcmaster.com/#standard-taps/=ke36u2
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long slot rockers are far less likely to bind on rocker studs

STUD GIRDLES ADD A GREAT DEAL OF RIGIDITY TO THE VALVE TRAIN
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typical factory pressed in rocker studs
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it should be obvious that the slot clearance in some rockers , especially with poly locks significantly limits rocker movement before clearances become an issue
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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
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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
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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

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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
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: press in vs threaded rocker studs

Postby grumpyvette » February 21st, 2010, 12:22 pm

praza wrote: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


http://youtu.be/dtC6nn5r7AE
http://youtu.be/ryPulDjh2hc


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

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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
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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




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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

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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

http://www.summitracing.com/parts/SUM-141010/?rtype=10
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http://www.summitracing.com/parts/CCA-4014/
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viewtopic.php?f=52&t=1769

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http://www.summitracing.com/parts/BRO-BR1230/?rtype=10
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STUD GIRDLES ADD A GREAT DEAL OF RIGIDITY TO THE VALVE TRAIN
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: press in vs threaded rocker studs

Postby grumpyvette » February 23rd, 2010, 3:52 pm

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."



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
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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,
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
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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

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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
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: press in vs threaded rocker studs

Postby grumpyvette » June 17th, 2014, 9:20 am

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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
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http://www.summitracing.com/parts/sum-900136
http://www.goodson.com/Rocker-Arm-Stud-Conversion-Kit/
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http://www.tooldiscounter.com/ItemDispl ... =POW351360
IF you have a decent drill press or mill this jobs hardly difficult

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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
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studs can be pulled with a stack of washers and a rocker nut used on the threads
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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
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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
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several places sell these alignment fixtures to insure the rocker stud alignment for both drilling and tapping and threads are consistently lined up
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done correctly with the heads machined, guide plates and thread locker on the rocker studs
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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
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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
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida


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