preventing leaky head bolts/studs



preventing leaky head bolts/studs

Postby grumpyvette » September 17th, 2008, 9:43 am

many guys have coolant leaks from studs and head bolts,you don,t need that P.I.T.A.
IF your going to use ARP main cap studs THE TORQUE SETTINGS ARE DIFFERENT than the original BOLTS, the STUDS ARE STRONGER, BUT,you might also consider that main studs generally install after cleaning the threads in the block with a tap,blowing them dry with high pressure air, coating the studs course threads with the thread sealant and fine threads end with the ARP thread lube, when you screw them into the block the full thread depth, by hand, or with an allen hex key,then get backed out one quarter turn, the main caps or heads are installed and the nuts torqued in stages to seat and hold the main caps,or heads, now LOOK at those STUDS, the end in the block,has threads that are SAE COURSE thread, the end your torquing the nut on is SAE FINE THREAD with a much different PITCH that requires less tq to give the same clamp loads.
never assume you know where coolant is leaking from UNTIL youve verified it, Ive seen guys replace head gaskets when it was a freeze plug or a leaking intake gasket that was the source of the coolant leaks
the bolts or threads leak IF the coolant flows up thru the threads, the path the coolant takes is exactly the same in either case, studs/bolts only LEAK when they are IMPROPERLY installed, a clean degreased thread in the block and on the stud or bolt you use then, installing either after dipping the thread section in the correct sealant, and letting the sealant start to dry on the threads for a few minutes, before installing them, prevents leaks, how the torque is applied to clamp the head has little effect.
Ive used BOTH studs and bolts on many engine builds and its proper procedure, and working with cleaned threads in both the block and fastener and use of the correct sealant on those threads not the studs or bolts that mater here.
the thread sealant stays liquid until exposed to the air, you need to allow the sealant on the threads a minute of air exposure to start to thicken before installing them,so the sealant forms a barrier to coolant flow in the threads.
in either case youll want to install all the studs or bolts with the sealant on the threads, and then torque them in sequence (a spiral pattern starting at the center and working outwards ), start at about 35 ft lbs than repeat increasing by about 10-15 ft lbs each time until you reach the specified ft lb value, I usually wait 5 minutes then go back and INDIVIDUALLY slightly loosen the bolts or nuts on the studs AND INDIVIDUALLY RE-TIGHTEN THEM TO THE FINAL TORQUE VALUE at least twice more and bring them back too the final torque value, this cycling tends to result in more consistent clamp values
Image
SBC HEADS
Small Chevy
Fastener Type Torque Spec
7/16 in. outer main cap bolt 65 ft.-lbs.
7/16 in. inner main cap bolt 70 ft.-lbs.
3/8 in. outer main cap bolt 40 ft.-lbs.
11/32 in. connecting rod bolt 38-44 ft.-lbs.
3/8 in. connecting rod bolt 40-45 ft.-lbs.
Cylinder head bolts 65 ft.-lbs.
Screw-in rocker arm studs 50 ft.-lbs.
Intake manifold bolts (cast iron heads) 30 ft.-lbs.
Oil pump bolt 60-70 ft.-lbs.
Cam sprocket bolts 18-20 ft.-lbs.
Harmonic damper bolt 60 ft.-lbs.
Flywheel/flexplate bolts 65 ft.-lbs.
Pressure plate bolts 35 ft.-lbs.
Bellhousing bolts 25 ft.-lbs.
Exhaust manifold bolts 25 ft.-lbs.
Image
Main cap bolt, 396-427 2-bolt 95 ft.-lbs.
Main cap bolt, 396-454 4-bolt (inner/outer) 110 ft.-lbs.
3/8 in. connecting rod bolt 50 ft.-lbs.
7/16 in. connecting rod bolt 67-73 ft.-lbs.
Cylinder head bolts, long 75 ft.-lbs.
Cylinder head bolts, short 65-68 ft.-lbs.
Screw-in rocker arm studs 50 ft.-lbs.
Intake manifold bolts (cast iron head) 25 ft.-lbs.
Oil pump bolt 65 ft.-lbs.
Cam sprocket bolts 20 ft.-lbs.
Harmonic damper bolt 85 ft.-lbs.
Flywheel/flexplate bolts 60 ft.-lbs.
Pressure plate bolts 35 ft.-lbs.
Bellhousing bolts 25 ft.-lbs.
Exhaust manifold bolts 20 ft.-lbs.
Big Chevy
Image

guys! Ive YET to have a single stud or bolt leak!

http://arp-bolts.com/pages/technical_installation.shtml

its simple! run a tap thru the threads, test screw the clean/dry stud by hand to verify no clearance or binding then ,clean them and dry the threads on the block and studs,before you start the assembly, and just dip the total threaded surface on the lower studs course thread end of the stud that screws into the block into the correct sealant. spin it in your fingers slowly as you move the stud to the hole in the block to keep from dripping sealant on the deck,

thread it into the block full depth , back it out a 1/2 turn and let it set up for a few minutes before assembling the head gaskets and heads,but assemble the heads while the sealants still fresh/liquid, torque too spec and let the engine set for a few hours (preferably over night)
IF you get leaks, thats NOT NORMAL (leaks) and the liquid permatex stuff
http://www.permatex.com/products/Automo ... ealant.htm
or
http://www.permatex.com/products/Automo ... ealant.htm

I use looks almost black, with a slightly reddish tint, you clean both threaded components and then coat both the threads (hole and plug)with the liquid sealant, then screw the components together, and let it set up for an hour or so before adding coolant, if you use it on head bolts you clean the block threads with a tap, degrease the bolts then dip the bolt threads in the container and drop them into place and torque them in stages while wet during the first 20 minutes before the stuff has time to set-up but add coolant only after a few hours so it has time to set up.remember not to allow coolant to contact the sealant for a few hours
I got asked if USING anodes, in an engine is a good idea?
ITS NOT ONLY A GOOD IDEA ITS MANDATORY IN SOME APPLICATIONS!
if you were for example to use aluminum heads on a cast iron block with a copper head gasket (something IVE done frequently)
you need to realize you've effectively built a battery if you don,t use both several ANODES and at least a 50% or higher concentration of anti freeze as the dissimilar metals will cause the aluminum, to disintegrate over time without the anodes and high anti freeze concentration.
Ive been building engines for over 40 years and yes I fully agree some head gaskets suggest installing them dry....I spray both sides wet with copper coat and have yet to have problems with them sealing, keep in mind the vast majority of head gaskets don,t "LEAK" they get damaged by "OVER HEATING" or "DETONATION DAMAGED" or " effected by coolant corrosion" then when they fail, its blamed on the "HEAD GASKET FAILURE" THATS A BIT LIKE BLAMING FLYS for CAUSING GARBAGE
READ THRU THESE THREADS
viewtopic.php?f=50&t=1222

viewtopic.php?f=50&t=50&p=1253&hilit=+sealant#p1253

http://www.devcon.com/products/products.cfm?familyID=386

viewtopic.php?f=50&t=50&p=12558&hilit=washers+bolts+studs#p12558

High Tackâ„¢ Gasket Sealant
Red colored, all-purpose sealant that holds even the heaviest of gaskets in place during assembly. Seals and bonds rubber, cork, paper, felt, and metal gaskets. Sets quickly to a very tacky film. Suitable to 500°F (260°C). Contains no ozone-depleting compounds. Resists gasoline, oil, kerosene,antifreeze, propane and butane.

the stuff works far more reliably than most thread pastes or thread sealants, it cleans ,off fingers with a scotch brite pad and gas or alcohol,....provided you have not let it set up on your skin very long, once its started too dry ...good luck

YES it works on BOLTS ALSO

head bolts #5, dip clean dry thread in

http://www.devcon.com/devconfamilyproduct.cfm?familyid=386&catid=69

or this

http://www.permatex.com/products/Automo ... ealant.htm

(NOT QUITE AS GOOD BUT STILL OK)

then insert and tq heads in place





use the correct stuff for the application, AND READ & FOLLOW THE DIRECTIONS it prevents PROBLEMS


studs put less stress & wear on the block deck threads, and provide more consistent clamp loads, the 12 point, stud nuts and washers tend to have less clearance issues in tight areas, than the head on a 6 point bolt, and are less likely to round off as the tq is applied, but be aware that getting the heads up and out in a confined engine compartment is generally a P.I.T.A. over studs that extend up several inches past the block when fenders and brake boosters, etc. are in the way
thanks grump can you tell me anything about "Undercut" studs are they worth the extra $$$

that depends on the application their used in, the under cut studs maintain their clamp force, more consistently over a longer stretch distance, let me explain that a bit
if you use the standard , studs on a cylinder head the heads get torqued in place at standard temps, when the engine heats up the metals expand, and the clamp loads tend to increase a bit,when it cools the metals contract,and the clamp loads tend to return to original levels, this cycles the stress and clamp loads, on an iron block with iron heads and even with aluminum heads the standard non-under cut studs are fine in most applications,because BOTH the studs and the head gaskets are designed to work with this repetitive cycle, if you have an all aluminum block and heads your probably better off with the under cut studs due to the greater dimensional shifts as the engine changes temp.
either design will tend to keep the clamp forces in a usable and predictable range, but the non-undercut studs are less likely to maintain the same exact clamp forces over the temp shifts the engine sees between running and cooling cycles.
short answer, on a iron block engine ID just sellect the standard ARP studs and follow the installation info posted earier in the thread, keep in mind aluminum thread strength fatigues far faster than iron or steel and it requires about 2.5-3 times the thread dia. to depth ratio to equal the resistance to stripping threads in aluminum vs about 1.7-2 times the thread dia. to depth ratio to equal the resistance to stripping threads in steel or iron

YES it works on BOLTS ALSO

OLD POST COVERS THAT INFO


I can,t believe the stuff I see at times..in the car mags that are SUPPOSED to be articles composed by guys who know what they are doing!!!!!!!
I picked up a copy of one of the more common, chevy based magazines and theres PICTURES of a guy dipping head bolts in yellow weather strip adhesive to be used as a thread sealant on the bolt threads (its not designed to come in direct contact with oil and/or high heat coolant),and its not going to give the correct tq readings either, and on the next page the guys gooping, GOBS of clear silicone like youll use to seal aquariums or bathroom fixtures 1/4 thick on/around the intake manifold ports, NEITHER SEALANT is DESIGNED FOR or is LIKELY to perform correctly IN EITHER APPLICATION, and WHERE does this guy think all that excess silicone will go once the intakes torqued down????
theres only two high probability's, it will flow into the port where it will eventually harden and get sucked into the cylinders or it may hang there causing a restriction in the port, or if it flows down, it gets into the lifter gallery where its eventually going to get into the oil pump pick up screen, restricting or blocking oil flow
i would not let these guys fix a flat tire let alone work on MY ENGINES all I can do is shake my head and wonder who if ANYONE screens these articles

always use the manufacturers suggested installation instructions, as some applications or gasket types REQUIRE differant lubes or sealants but heres a rought guide


head bolts #5, dip clean dry thread in
http://www.devcon.com/products/products ... milyid=386

or this
http://www.permatex.com/products/Automo ... ealant.htm
(NOT QUITE AS GOOD BUT STILL OK)

then insert and tq heads in place


head gaskets #3
main bolts #2
rod bolts #2
oil pump stud and nut #4
oil pan bolts #5
oil pan gasket #6
cam spocket bolts #4
timing cover gasket #6
timing cover bolts #1
intake bolts #1
intake gasket #6
thermostat housing bolts #5
thermostat housing gasket (also do you really need it) usually yes #6
Exhaust manifold/header bolts #1
Exhaust manifold/header gaskets #3
Water pump bolts #5
water pump gaskets #6
fuel pump #6
crank/damper bolt #1
Torque converter bolts #4
flywheel/flexplate bolts #4
bellhousing bolts #2

1 antiseize
2 oil or ARP thread lube
3 copper coat spray gasket sealer or apply dry in some cases (see manufactures suggestions)
4 loctite (red or blue depends on application ,read the lables)
5 http://www.devcon.com/products/products ... milyid=386

Fast-drying all-purpose sealant dries to a highly tacky, non-brittle film. A reliable general adhesive.Remains effective under temperatures of -65°F to 500°F (-54°C to 260°C). Resists gasoline, oil, antifreeze, axle lube, kerosene, propane and butane. Level 3*

6 black high temp RTV


use the correct stuff for the application, AND READ & FOLLOW THE DIRECTIONS it prevents PROBLEMS
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: preventing leaky head bolts/studs

Postby grumpyvette » October 24th, 2008, 8:30 am

keep in mind if you follow that info posted above and below in this thread,and still have a head bolt leaking coolant, theres also the chance the coolant is NOT seeping past the bolt threads but the coolant leak is from either a defective head gasket, or use of the wrong head gasket, for the application, or in some cases use of a set of cylinder heads that are not designed as a direct replacement for the original cylinder heads or a combination of several of these factors, the fact that the heads will bolt to the block IS NOT ALWAYS an indication they may safely be used.
head bolt length can and does vary with the application, and the use of the wrong bolts or studs can also cause problems, leaking intake gaskets or a cracked cylinder head casting,or the potential for tripped threads ,in the block, or a bolt thread that is cracked in the block, could be an issue!
which would explain why the sealant on the thread repairs were worthless in stopping the coolant flow, at times a bolt thats too long that bottoms out before the bolt head shoulder can apply the proper clamp pressure is also a common fault.
dipping the clean dry threads of a head bolt in a semi flexible sealant before the bolt or studs inserted in the clean dry threaded hole is often a good idea on bolts or studs that enter the coolant passages
Image

Image
some cylinder head and engine block castings and some blocks that you might assume are compatible may not have the correct configuration to seal correctly and at times its not this obvious
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: preventing leaky head bolts/studs

Postby grumpyvette » November 25th, 2008, 11:31 am

these look great, and theres little doubt they are a quality tool


1: http://www.emaxaction.com/cdi1503mfrmh.aspx
2: http://www.toolsource.com/torque-wrench-microadj-metal-handle-20150-ftlbs-plain-head-p-95221.html


CONSISTENCY and REPEATABILITY ,rather than exact torque, is the key, if your off a ft lb its not catastrophic.
Ive used both a SEARS and a HOME DEPOT TQ WRENCH,S FOR MANY YEARS. built over 150 engines and had zero problems

consistent technique and consistency in the way you lube and work the torque loads up in stages and having the bolts and studs lubed and cycling, the bolt/stud up to the recommended tq and loosening it and repeating that several times tends t0o give consistent results, USE ARP FASTENERS


http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100058237

http://www.sears.com/shc/s/p_10153_12605_00944595000P?vName=Tools&cName=Mechanics+Tools&sName=Torque+Wrenches

btw rod bolts SHOULD have a stretch gauge used but its not 100% mandatory, cycling them up to spec and releasing the tq then repeating several times with a tq wrench, following the APR instructions gets you very consistent results IVE checked the tq wrench results with the stretch gauge

http://store.summitracing.com/partdetail.asp?autofilter=1&part=ARP%2D100%2D9942&N=700+115&autoview=sku

worth reading

http://blogs.hotrod.com/6244144/editori ... index.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: preventing leaky head bolts/studs

Postby grumpyvette » November 29th, 2008, 11:03 pm

ANY engine that has the head bolts or head studs enter the coolant passages like the chevy O.E.M. blocks do, has the potential for coolant under pressure to push up the threads and cause a slow coolant leak.
the head studs or bolts have a tendency to move slightly with the constant expansion and contraction of the engine due to heat and cooling cycles .
Image
IF your going to use ARP main cap studs THE TORQUE SETTINGS ARE DIFFERENT than the original BOLTS, the STUDS ARE STRONGER, BUT,you might also consider that main studs generally install after cleaning the threads in the block with a tap,blowing them dry with high pressure air, coating the studs course threads with the thread sealant and fine threads end with the ARP thread lube, when you screw them into the block the full thread depth, by hand, or with an allen hex key,then get backed out one quarter turn, the main caps or heads are installed and the nuts torqued in stages to seat and hold the main caps,or heads, now LOOK at those STUDS, the end in the block,has threads that are SAE COURSE thread, the end your torquing the nut on is SAE FINE THREAD with a much different PITCH that requires less tq to give the same clamp loads.
the bolts or threads leak IF the coolant flows up thru the threads, the path the coolant takes is exactly the same in either case, studs/bolts only LEAK when they are IMPROPERLY installed, a clean degreased thread in the block and on the stud or bolt you use then, installing either after dipping the thread section in the correct sealant, and letting the sealant start to dry on the threads for a few minutes, before installing them, prevents leaks, how the torque is applied to clamp the head has little effect.
Ive used BOTH studs and bolts on many engine builds and its proper procedure, and working with cleaned threads in both the block and fastener and use of the correct sealant on those threads not the studs or bolts that mater here.
the thread sealant stays liquid until exposed to the air, you need to allow the sealant on the threads a minute of air exposure to start to thicken before installing them,so the sealant forms a barrier to coolant flow in the threads.
Image

Image
Head Studs
Image

Image

Image
a
Image
b
Image
http://www.arp-bolts.com/catalog/Catalog.html

Why do they get backed out by one turn? I'm trying to think of the physics behind it, but I can't think of any good reason. What is the physics answer, Grumpy?

the threads must bear evenly and align correctly with the studs centerline, for the stud to apply max loads over the total threaded surface ,the threaded section must be under tension alone and engage the total threaded surface in the block, if the stud is torqued into place, youve preloaded the threads bearing the load and they are partly under compressive loads ,your basically jacking the bottom of the threaded hole away from the threaded section, and appling THOUDANDS of lbs of extra stress to the blocks web area if you torque the threads to the same 100 ft lbs the original bolts were tightened to, the threads in the block will now have added stress once the full tension loads on the studs and main caps is applied by torqing the nuts on the studs ,theres added stress on the block, if the studs have bottomed out and are pushing on the bottom of the threaded hole making the block web area more likely to crack or the crank saddles to distort.
keep in mind FACTORY BOLTS are made slightly shorter to PREVENT the bolt tip bottoming out in the hole, but bolts cause wear on the threads because they are tightened while the bolts still advancing deeper into the threaded block, studs cause far less wear because they fully engage the threads bearing the loads before the tensive load is applied

heres what ARP says
"STUDS vs. BOLTS

ARP recommends the use of main studs over bolts whenever possible for several key reasons. First is the ability to obtain more accurate torque readings because studs don’t “twist” into the block. All clamping forces are on one axis. By the same token, there is less force exerted on the block threads, which contributes to improved block life (very critical on aluminum blocks). Finally, there are factors of easier engine assembly and proper alignment of caps every time"

ARP's instructions (for head studs)state that you should thread the studs into the block until they're hand-tight, but with the head on the block, this is difficult. Fortunately, ARP was thoughtful enough to incorporate a fitting for an Allen wrench into the head of each stud. So, using an Allen wrench, I threaded the studs into the head until I could no longer turn the wrench with two fingers. This method seems to have worked nicely

1. Clean and chase appropriate threads in
block to ensure proper thread engagement
and accurate torque readings.
2. All hardware (and caps) should be
cleaned and inspected prior to installation,
looking for any shipping damage or defects.
3. Screw studs into block, finger tight
ONLY. For permanent installation, apply
Loc-tite (or similar adhesive) sparingly
to threads. Be sure and install the caps
promptly before the cement sets to prevent
misalignment of studs in block.
1. Clean and chase appropriate threads in
block to ensure proper thread engagement
and accurate torque readings.
2. All hardware (and caps) should be
cleaned and inspected prior to installation,
looking for any shipping damage or defects.
There are a number of important considerations
when installing ARP main studs.
3. Screw studs into block, finger tight
ONLY. For permanent installation, apply
Loc-tite (or similar adhesive) sparingly
to threads. Be sure and install the caps
promptly before the cement sets to prevent
misalignment of studs in block.

First and foremost is making sure the
block and studs are as clean as possible.
Foreign matter and debris can easily affect
the quality of thread engagement and
cause erroneous torque readings. Do not
re-cut threads in the block – use the special
“chaser” taps as listed on page 87 of this catalog.
This will preserve the integrity of the
threads and provide better engagement.
Calibrate your torque wrench – even new
wrenches have been known to be off by as
much as 10 foot pounds! Use consistent
tightening techniques.
4. Install main caps, checking for binding
and misalignment. Lubricate threads, nuts
and washers with oil or ARP moly assembly
lubricant before installation. Note that torque
specs will vary by lubricant. Moly lube is
most consistent. Have block align honed.
5. Using the instructions provided with
the studs, tighten the nuts to proper
torque values three times. NOTE: If using
Loc-Tite or similar cement, proper preload
must be achieved prior to it setting up.

viewtopic.php?f=50&t=342&p=10864&hilit=torque+wrench#p10864


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

I usually use this sealant (sparingly)on the course ends of main cap studs that screw in hand tight, and ESPECIALLY on head studs that enter water jackets
read these threads
viewtopic.php?f=50&t=1222

viewtopic.php?f=44&t=805&p=1171&hilit=sealant+silicone#p1171

viewtopic.php?f=27&t=1262&p=6142&hilit=taps#p6142

viewtopic.php?f=59&t=1264&p=13269#p13269

http://www.permatex.com/products/Automo ... ealant.htm

viewtopic.php?f=51&t=3774&p=10002&hilit=bottoming+taps#p10002


Image
alumimum heads ALWAYS require head bolt washers and the flat surface faces the head the inner bevel faces the bolt head
on head STUDS the same things required on aluminum heads to get even clamp loads and no galling




Image
this stuff is pretty much interchangeable
Image

with this stuff in THAT APPLICATION
recommended operational temp range is just a tiny bit different from what Ive seen, one has about a 30F higher recommended temp, youll never get close in a properly operating engine to either
Image
I can,t remember using this stuff but it appears to be similar

you need to use a thread sealant on the thread that remains semi flexiable, so you don,t apply any sealant to the studs threads while honeing the block, and only install that thread sealant on the threads within an hour or so of torqureing the stud threads with the heads in place during the final assembly so the sealant firms up in its operational location under the loads and pressure conditions its suppose to deal with, if you use a non-flexable thread sealant well in advance of final assembly your changing the thread loads and block distortion and more than likely effecting the sealant on the thread distribution, that can lead to coolant leaks

both of these work great at sealing head bolt threads, and freeze plugs etc.


viewtopic.php?f=50&t=1222
if you don,t have a particular engines torque sequence its a safe bet that you start with the center head bolts and tighten each , in stages in a spiral outward pattern, then repeat the sequence with each increased torque setting movng in that same spiral increasing diam spiral moving from the center to outer bolt locations.
Image
SBC HEADS
Image
Big Chevy
Image


keep in mind the course thread section is not being screwed in or the threads moved as the nut on the fine thread upper end is torqued to spec. and that thread requires the ARP thread lubricant to get the correct stretch and that stud needs to be cycled up to full torqure then released and retorqued,a minimum of three times to get the stretch/tq correct

I rarely use anything BUT dead soft pure copper head gaskets sprayed damp, with copper coat spray, on both sides, installed on my engines, Ive YET to have any leak in over 18 years Ive used them
Image
now these embossed copper gaskets (above) are supposed to be the best choice, but Ive never seen or used those
Image
these flat copper gaskets are supposed to be used with a wire fire ring with a groove machined into the block,Ive been successfully using these gaskets
Image
without those for decades by just spraying them damp with copper coat and have never yet had one fail

Image
when installing almost any head gasket, but especially with a copper head gasket be sure to put on two wet even coats on both sides of the head gasket and install and torque while the copper coat sprays still damp
(mostly because they are re-usable after a good cleaning) and I pull the engine apart frequently for cam swaps and other mods
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: preventing leaky head bolts/studs

Postby grumpyvette » September 6th, 2009, 7:53 pm

MOST SENSORS AND PLUGS ARE THREADED FOR NPT

THREADS with NPT (national pipe thread)thread sizes

these are two sealants I use

http://www.permatex.com/products/Automo ... lant_b.htm

http://www.permatex.com/products/Automo ... ealant.htm

http://www.engineershandbook.com/Tables/npttap.htm

http://www.cutting-tool-supply.com/Tech ... VsNPTF.htm

NPT Vs. NPTF Taper Pipe Threads

The two most common taper pipe threads used in the United States are NPT and NPTF. Applications range from electrical conduits and hand railings to high-pressure pipe lines that carry gas or caustic fluids. NPT threads are for mechanical or low-pressure air or fluid applications and require the use of sealing compounds like Teflon tape, to provide the seal. When the application is more critical, and the sealing compound may fail due to high heat or pressure, NPTF Dryseal threads are used. This mechanical seal is produced by the mating and slight crushing of the threads when a wrench is applied to tighten the fittings.

Visually, both threads appear to be identical. Both have a ¾” taper over one foot of length. Both have the same pitch diameter at the top of the hole of internal threads or end of the pipe on external threads, and both have the same thread lengths or depths. However, there is a subtle difference in the thread form that differentiates the two. The major and minor diameters of both threads differ slightly. With NPT threads, after a wrench is applied, slight spaces at the major and minor diameters may exist that would allow the assembly to leak and therefore a sealing compound is used to fill any gaps. On the other hand, NPTF threads are designed to ensure that sufficient crushing of the entire thread form will take place to produce a mechanical seal.

How does the difference in thread forms effect the tooling used to produce NPT and NPTF threads? Taps are available for both NPT and NPTF threads having the appropriate form to produce each type of thread. Since NPT threaded parts require sealing compounds, it is acceptable to use an NPTF tap for NPT applications. However, NPT taps cannot be used for NPTF applications, as it will likely produce a thread that will leak. The same is true of external threads. In most cases the tap drill is the same for both forms.

The most significant difference in the two threads is the inspection required. Since sealing compounds will be used for NPT threads, only a single plug with a step, known as an L1 plug (internal thread) or a single thin L1 ring (external) are required to check size. However, since the taper and the position of major and minor diameters are so critical to the sealing of NPTF threads, the additional threads in the assembly known as L2 and L3, and the major and minor diameters are inspected with either special plug or ring gages.
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Re: preventing leaky head bolts/studs

Postby grumpyvette » March 15th, 2011, 7:08 pm

yes Ive seen several posts on the internet that indicate bolts don,t tend to seaep coolant and studs do tend to leak coolant?
can anyone explain to me why a threaded lower section of a head bolt in the same engine blocks, threaded holes magically stops leaks, of coolant traveling up along the bolts threads while an identical diameter and thread pitch section of threads on a head stud , with identical dimensions made by the same manufacturer some how caused those same threads to leak ?

because Ive assembled many dozens of engines with both types of fasteners and Ive yet to have either fasteners threads leak coolant...logic says that if you get different results its because your installing them in a different manor, or your using a different sealant or your torquing the heads excessively while using the finer pitch threads on the studs upper end when you install the washer and nuts to clamp the heads
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Re: preventing leaky head bolts/studs

Postby grumpyvette » March 15th, 2011, 7:13 pm

yes Ive seen several posts on the internet that indicate bolts don,t tend to seep coolant and studs do tend to leak coolant?
can anyone explain to me why a threaded lower section of a head bolt in the same engine blocks, threaded holes magically stops leaks, of coolant traveling up along the bolts threads while an identical diameter and thread pitch section of threads on a head stud , with identical dimensions made by the same manufacturer some how caused those same threads to leak ?
obviously, if you have coolant getting mixed with the oil theres a coolant leak into the engine, you could be dealing with a blown head gasket, leaking intake gasket, cracked cylinder head, cracked block, loose valve guide or other issues so you need to tear it down and locate the source of the coolant getting into your oil before it does major damage, which it will rather quickly

because Ive assembled many dozens of engines with both types of fasteners and Ive yet to have either fasteners threads leak coolant...logic says that if you get different results its because your installing them in a different manor, or your using a different sealant or your torquing the heads excessively while using the finer pitch threads on the studs upper end when you install the washer and nuts to clamp the heads

Head studs are bolt-like parts that are threaded on both ends. One end threads into the engine block. The head (or heads if it is a V-shaped engine) of the engine is then installed onto the block by sliding it down over the studs. Nuts are then threaded onto the head studs to hold the head in place. Head studs ensure that there is no movement or stretching of the head when the engine encounters extreme heat. ARP head studs are a great performance upgrade for modified engines since they are stronger and much more durable than the majority of stock head studs.


read thru these

http://arp-bolts.com/pages/technical_to ... l#ustorque

http://arp-bolts.com/pages/technical_installation.shtml

ARP Head Studs vs. Head Bolts


ARP Cylinder Head Studs. It is for good reason that virtually every top professional engine builder relies on ARP head studs for their all-out competition powerplants. Simply stated, there’s not a better stud setup on the market today.

For openers, ARP Head Stud Kits uses a premium grade 8740 alloy that is rated far superior to “aircraft” quality. Then, each stud is placed vertically in special racks and precisely heat-treated to 200,000 psi. This procedure ensures complete heat penetration and the results are far superior to those lesser quality studs from other manufacturers who just dump pieces in a basket and hope for the best.

ARP Head Stud KitsFollowing heat-treat, each ARP Head Stud is centerless ground to make it as close to perfectly concentric as possible. This procedure involves about ten very slight cuts and results in an exceptionally straight part. It’s important to note that lesser quality studs are not even centerless ground – the material is thread rolled in bar stock form (mostly before heat-treat, when the material is easier to machine). Because ARP Head Stud Kits are manufactured to such exacting tolerances, you will note that gaskets and cylinder heads literally glide into position and are perfectly aligned – something that won’t happen with inferior quality head studs.

ARP Head Stud Kits are thread rolled after heat-treat, which gives them about 1000% (that’s ten times) better fatigue strength than those studs that are threaded prior to heat-treat (a very common industry practice). It costs a lot more to do it this way, because it’s tough on tooling, but the results are well ARP Head Studworth the extra effort.

You will also note that ARP offers specially undercut studs for several engines. This procedure (done only to the shorter studs) more equalizes the “stretch” of both studs, which makes for a more consistent clamping force – and one that compensates for head gasket compression when the cylinder heads are installed. This helps prevent blown head gaskets, and assures optimum engine sealing!

Premium quality heat-treated 8740 chrome moly steel head stud kits are available for most every domestic and import applications. You won’t find a better quality stud on the market from any other source. Look for ARP stamped on each stud as your assurance of quality.

ARP head stud kits are available with your choice of conventional hex nuts or compact 12-point nuts. Premium quality parallel ground washers are also included with each kit. Clearly, they are the best on the market today, and the favorite of leading professional engine builders in all forms of racing.
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Re: preventing leaky head bolts/studs

Postby Indycars » March 16th, 2011, 8:49 am

Looks like it might be a good idea to run all critical fasteners thru 3-5 cycles, before I take the block in for Main Line Hone, Deck Plate Hone etc. Especially if you're using anything besides the ARP Lube. Also I will need to supply the machine shop with the "ARP Ultra Torque" lube.

http://arp-bolts.com/pages/technical_installation.shtml
PreloadGraph.gif

The Lubricant Is The Key

The main factor in determining friction in a threaded fastener is the lubricant used, and therefore influences the torque required for a particular installation. One of the most overlooked aspects of choosing a fastener assembly lubricant is…the lubricant's ability to "control" the normal function of friction inherent in all high performance engine fasteners. As discussed earlier in this section, friction is at its highest point when a new fastener is first tightened. This "friction" inhibits the fasteners ability to achieve the required preload on the first several cycles. In fact, ARP's in-house Research and Development department has proven that new fasteners using motor oil and other commonly used lubricants such as Moly and EPL typically require 5-7 cycles before final torquing to level out the initial friction and achieve the required preload. Slicker lubricants may reduce the required torque by as much as 20-30% to achieve the desired preload, but compromise in areas of major importance such as preload repeatability, and may yield the fastener prematurely. Typically, the slicker the lubricant, the greater the "preload scatter" or preload error there will be during installation.
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Re: preventing leaky head bolts/studs

Postby grumpyvette » March 16th, 2011, 9:07 am

thanks for posting that , I forgot to mention that specifically
Ive always thought it was rather odd that ARP suggests using oil,or other lubricants on bolt threads with the sbc engine when you need to use a thread sealant because the bolt threads enter the coolant passages,you can,t mix the two on the threads without having increased the chance of coolant leaks, now you can use the sealant on the stud lower course threads and the oil,moly or other lube on the upper fine threads so that makes sense, but they often fail to get into that detail.
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Re: preventing leaky head bolts/studs

Postby Indycars » March 16th, 2011, 5:42 pm


I don't have my aluminum Brodix IK heads, but I want to run thru a few cycles on the ARP head bolts before I take the block to the machine shop. I can't think of any reason why I can't use my Chevy cast iron heads with the old head gaskets for this.

Any opinions on this ???
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Re: preventing leaky head bolts/studs

Postby grumpyvette » March 16th, 2011, 6:17 pm

Indycars wrote:
I don't have my aluminum Brodix IK heads, but I want to run thru a few cycles on the ARP head bolts before I take the block to the machine shop. I can't think of any reason why I can't use my Chevy cast iron heads with the old head gaskets for this.

Any opinions on this ???

it probably won,t hurt but its a rather waste of time, you simply cycle the head bolt stretch during the assembly process by torquing the bolts in several stages to full torque,with the thread sealant on the threads, loosening them and re-torquing the bolts to full torque about 3-4 times during the final assembly process, lets say the bolts you select say torque to 65 ft lbs, so you torque them all to 45 ft lbs, then 55 ft lbs then 65 ft lbs in three sequence,s then back the tension off and re-tighten to 55 ft lbs, then 65 ft lbs, then back them off and re-, tighten to 65 ft lbs, wait 1/2 an hour and check tension by re -torque them to 65 ft lbs without loosening them, this time, the whole process is best left till the final assembly

viewtopic.php?f=51&t=10464&p=43788#p43788

Image
Small Chevy
Fastener Type Torque Spec
7/16 in. outer main cap bolt 65 ft.-lbs.
7/16 in. inner main cap bolt 70 ft.-lbs.
3/8 in. outer main cap bolt 40 ft.-lbs.
11/32 in. connecting rod bolt 38-44 ft.-lbs.
3/8 in. connecting rod bolt 40-45 ft.-lbs.
Cylinder head bolts 65 ft.-lbs.
Screw-in rocker arm studs 50 ft.-lbs.
Intake manifold bolts (cast iron heads) 30 ft.-lbs.
Oil pump bolt 60-70 ft.-lbs.
Cam sprocket bolts 18-20 ft.-lbs.
Harmonic damper bolt 60 ft.-lbs.
Flywheel/flexplate bolts 65 ft.-lbs.
Pressure plate bolts 35 ft.-lbs.
Bellhousing bolts 25 ft.-lbs.
Exhaust manifold bolts 25 ft.-lbs.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
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Re: preventing leaky head bolts/studs

Postby Indycars » March 16th, 2011, 6:30 pm


Since torquing head bolts create distortion in the cylinders, then why wouldn't it be a problem when the machine shop torques the deck plate to the block for honing ???

If the fasteners are NOT reaching the same preload, then the amount of distortion would be different at the machine shop, then when it comes time for final assembly.
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Re: preventing leaky head bolts/studs

Postby grumpyvette » March 17th, 2011, 6:46 am

I think were talking about two distinctly different things,
(1) yes youll need to have the block under stress with bolts, or studs and a torque plate to duplicate the stress on the bore walls , that a clamped cylinder head induces on the bore walls to get the hone done correctly
Image
Image
(2)bolts and studs don,t reach their full operational stretch or take a full set in length until they get cycled at least 3 times under stress / clamp loads
Image
Image
In any application where your tightening a nut on a stud , such as on the outer threaded ends of main cap studs or head bolt studs, youll want to use a lube on the threads that gives consistent torque reading from your torque wrench indicating the correct bolt or stud TENSION, oil and MOLY assembly lube and various thread sealants do not always do that,the end in the blocks course threads have thread sealant, the fine threads on the outer end require a totally different lubricant
just some info for future builds
Image
aluminum heads ALWAYS require head bolt washers with oil or ultra lube to get consistent clamp values and the flat surface faces the head the inner bevel faces the bolt head
on head STUDS the same things required on aluminum heads to get even clamp loads and no galling

unlike a OEM block DARTS blocks have blind threaded head bolt holes that don,t enter the water jacket so you need to be sure the threads are clean, theres no crud in the threaded holes and you use minimal thread sealant on the lower threads because theres little chance off coolant leaking up thru the threads like with an OEM block where head bolts enter the coolant passages

Image
this should be used only in head bolt holes that don,t enter water jackets in the block on the lower threads

Image
Image
viewtopic.php?f=50&t=50&p=12558&hilit=threads+lube+torque#p12558
(3) Ive always thought it was rather odd that ARP suggests using oil,or other lubricants on bolt threads with the sbc engine when you need to use a thread sealant because the bolt threads enter the coolant passages,you can,t mix the two on the threads without having increased the chance of coolant leaks, now you can use the sealant on the stud lower course threads and the oil,moly or other lube on the upper fine threads so that makes sense, but they often fail to get into that detail.

RELATED INFO

viewtopic.php?f=50&t=50&p=12528&hilit=studs+sealant#p12528

viewtopic.php?f=53&t=3897&p=11708&hilit=bore+distortion+hone#p11708

viewtopic.php?f=51&t=588&p=764&hilit=hone+plates+block#p764

viewtopic.php?f=51&t=976&hilit=torque+plates
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
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Re: preventing leaky head bolts/studs

Postby Indycars » March 17th, 2011, 7:27 am

grumpyvette wrote:I think were talking about two distinctly different things,
(1) yes youll need to have the block under stress with bolts, or studs and a torque plate to duplicate the stress on the bore walls , that a clamped cylinder head induces on the bore walls to get the hone done correctly

(2)bolts and studs don,t reach their full operational stretch or take a full set in length until they get cycled at least 3 times under stress / clamp loads


If each time we torque the head bolts the preload goes up, say from 17,000 psi to 18,500 psi and then levels off, then the distortion in the cylinder walls will be different at each load. If the machine shop does the torque plate hone and it's the first time the bolts have been torqued it will be at the 17,000 psi load. I get it home and do several preassembly checks and then I perform the final torque and the preload is 18,500 psi.

The distortion will be different, thus the cylinder will be NOT be round now. Comments please.
Rick
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Re: preventing leaky head bolts/studs

Postby grumpyvette » March 17th, 2011, 7:44 am

in almost every case the machine shop will not be using your head bolts to clamp the torque plate simply because , they CAN,T they won,t fit due to the torque plate being thinner and a consistent 2"-2.5" thick while the heads are thicker and have varied distances from the block deck, the machine shop will simply use a set of grade 8 bolts that match the torque plate,
YOU will be the one using the head bolts, and while head bolts, or studs tend to take a set after the first three cycles of stretch and relax, Ive used the same head bolts or studs for several rebuilds on dozens of engines and have used the same torque specs with zero problems

first gen Chevy SBC or BBC v8 bolts or studs used at the recommended clamp loads should not be overly stressed, and can be re-used several times
the newer TORQUE TO YIELD bolts on some of the newer engines are a one time and pitch in the dumpster deal, so don,t confuse the two types of fasteners

viewtopic.php?f=50&t=342&p=10864&hilit=torque+wrench#p10864

Image


Image
Image
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
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Re: preventing leaky head bolts/studs

Postby Indycars » March 17th, 2011, 7:54 am


Ok, I didn't think about the machine shop NOT using my head bolts because of the torque plate. Oh well.....the theory was good. :)
Rick
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- Check Out My Dart SHP Engine Project: viewtopic.php?f=69&t=3814
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