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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 08:36
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This is straight from the ARP website.  I just thought some of you may be interested in why they were a good idea.
HEAD STUDS vs. BOLTS... A TECHNICAL DISCUSSION
ARP's factory Tech Representatives are often asked which is better, cylinder head studs or bolts. The answer, invariably, depends on the installation. On many street-driven vehicles, where master cylinders and other items protrude into the engine compartment, its probably necessary to use head bolts so that the cylinder heads can be removed with the engine in the car.
For most applications, however, studs are recommended. And for good reason. Using studs will make it much easier to assemble an engine (especially a racing powerplant which must be serviced frequently and quickly!) with the cylinder head and gasket assured of proper alignment.
Studs also provide more accurate and consistent torque loading. Heres why. When you use bolts to secure the head, the fastener is actually being twisted while its being torqued to the proper reading. Accordingly, the bolt is reacting to two different forces simultaneously. A stud should be installed in a relaxed mode never crank it in tightly using a jammed nut.
If everything is right, the stud should be installed finger tight. Then, when applying torque to the nut, the stud will stretch only on the vertical axis. Remember, an undercut shorter stud will have a rate similar to a longer, standard shank stud. This provides a more even clamping force on the head. Because the head gasket will compress upon initial torquing, make sure studs and bolts are re-torqued after the engine has been run.
[Updated on: Sun, 11 July 2004 08:40]
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Location:
Sydney
Registered:
June 2004
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 08:50
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i am not questioning the benefits of the studs as i am getting a set from yellorolla
(if anyone wants then PLEASE contact him ASAP and we can get them a whole lot cheaper than the already AMAZING price offered!!!!!!!!!!!!!!!!)
BUT QUESTIONS:
when removing the nut, would the nut itself come off or would the stud loosen and come off too? i mean there is nothing holding the stud in place so when undoing the nut wouldnt the stud undo aswell?
if the stud loosens then wont the thread pitch stretch and therefore the stud would need to be replaced? i know with head bolts that once they are removed they should be replaced as the thread pitch changes when relaxed due to the high tension it was under previously
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Location:
Perth
Registered:
May 2003
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 09:33
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I would personally add a small amount of Loctite to the thread of the stud so that once screwed in (finger tight) it shouldnt unscrew when loosening off the head nuts.
Most head bolts off older cars that I know of (with the exception of Camira, Pulsar and a few others) can be re-used provided the bolts aren't tightened excessively. Provided the bolts are tensioned to manufacturer's specs (and you have oiled the bolts to reduce friction on the threads and under the head of the bolt), the material the bolt is made from should only stretch with-in its elastic range and therefore when undone, the bolt should take up its original shape.
Over tensioning results in plastic deformation and hence stuffed head bolts.
Oldcorollas would be the best on this subject.
fade-e I have pm-ed you regarding the studs.
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 09:52
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you use loctite only when you are into a water jacket as you find the studs bottom out anyway! you must clean the block threads before you put studs or bolts in and i mean clean them till there is nothing coming out of them. studs are better as you get an even torque but are not worth it for a streeter that isnt high performance that isnt being stripped every 20k km. i have studs top and bottom as mine will get pulled apart a fair bit and runs huge boost.
run head bolts unless you are going to run big boost and or you intend to strip the motor often.
mick
p.s remmeber to use lube when torquing you studs or bolts to get the right torque but dont use to much! theres a bit more to it but unless you are going to trail fit the engine internals ten times there is no use!
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Location:
Sydney
Registered:
June 2004
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 10:31
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Hey Peoples! just to reiterate what i mentioned before....
YELLOROLLA (and even me) is trying to gather as many people as he/we can together to bulk buy head studs... the set comes as 10 with nuts
now these usually retail over $400 for the set and if memory serves me right yellorolla can get them at under $250 if we can get numbers up
now hopefully yellorolla will read this sometime soon and add to what i have said or correct me anywhere here but in any case PLEASE people if anyone is interested then either PM yellorolla or myself (and i will pass it on to him)
now i know for a couple hundred bucks you can do a bit to your motor and stuff but if you are interested in motor reliability then take this offer up!!!! you dont want to spend heaps on your motor to be blowing heads and gaskets all the time
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 10:46
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18R-G people this also includes you potentially!
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Location:
Lost in the K hole
Registered:
May 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 11:24
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gotta agree with mick on this one - studs are great from a technical point of veiw, but for practical purposes (which goes for almost everyone on these forums) the bolts are a better option.
maybe if you regularly pulled the head off your engine OUT of the engine bay, but otherwise.... meh!
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Location:
tallahassee FL usOFa
Registered:
May 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 13:06
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i believe most of the "improvement" comes from higher tension that's the result of less thread friction using a quality/fresh stud & nut, as opposed to the stock bolt & threaded cast iron block.
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Location:
Lost in the K hole
Registered:
May 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 13:11
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| allencr wrote on Sun, 11 July 2004 23:06 |
i believe most of the "improvement" comes from higher tension that's the result of less thread friction
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its not higher tension (any monkey can hang off a torque wrench), it's, as rod states more accurate and consistent torque loading.
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Registered:
May 2004
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 17:12
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having made bolts for a living,
what duz torque measure?
the friction and imperfections of the threads
and THE STRETCH OF THE BOLT/STUD
THAT is wut keeps stuff together and from failing
measure your hed bolts wen you get them
toy spec. for 22r/e bolts is .001" of stretch
measure em wen you take it apart
STRETCHED OR NOT ???
rod bolts are properly MEASURED, NOT torqued ...
unless you are too cheap to buy the tool like me
some bolts are made to throw away on one use
NEVER EVER re use em
ALWAYS ALWAYS ALWAYS retorque as the hed gasket continues to flatten after torquing and on my motor that is a hed gasket endangering LARGE distance
i would also retorque periodically
i think if all owners did this, i wouldn't see all the 22r/e posts about blown hed gaskets
not due to overheating
ARP's torquing instructions are insufficient and confusing
you stretch the bolt to torque 5 times in a row
i've had my 22re hed torqued to 80 ft. lbs. with ARP studs
you lube the nut/threads first so the stud turning never happens on removal
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Location:
Lost in the K hole
Registered:
May 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Sun, 11 July 2004 17:25
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| toynado wrote on Mon, 12 July 2004 03:12 |
THE STRETCH OF THE BOLT/STUD
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exactly...
but how do you measure the strech of a bolt/stud when installed in an application like a head? you cant, so you estimate the stretch based on applied torque.
using studs instead of bolts simply results in more accurate estimation of final stretch based on this applied torque... ie youre more likely to have fastened things more accurately and consistently
rod bolts are much simpler
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Location:
Brisbane
Registered:
October 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Mon, 12 July 2004 09:19
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there are 2 types of head bolts available {non ARP i mean},
std bolts, reuseable time and time again
and torque-to-yield, the torque to yield is the one where u "tighten to 50nm, back all the way off, turque to 25nm aqnd turn 90 degs and turn 90 degs again". NEVER re-use them cause it will end in tears.
how r u supposed to make the stud stay in the block when u pull the head, i suppose it doesnt matter, cause u can just pull the nut off the stud and re-insert it.
as head bolts/studs dont go into water/oil galleries then there wouldnt be a problem using oil/loctite would there.
witzl, why should 18RG ppl be included, do they potentially have HG problems
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On Probation
Location:
North East NSW
Registered:
December 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Mon, 12 July 2004 10:55
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a stud with no clamping force being applied to it will not wind out with a nut, unless the nut is applying vertical loading to the threads of the stud (ie: you're pulling on the nut as you undo it with your fingers). it doesn't really matter anyway, if the stud winds out you just let it, you thread your nut off, and you wind the stud back in the same way it got there in the first place, easy
whilst studs are fantastic for manifolds (especially problematic ones like K motor extractors), i would tend to say that a new OEM set of head bolts, at less than half the price of a set of ARP head studs last time i looked, would be sufficient to provide even and accurate enough clamping force to a street motor
if you're running an oft-disassembled motor, or a highly modified motor (race motor, bulk boost, etc) then chances are if you can rebuild it yourself and/or can get it to make big power reliably, they you're already cluey enough to know when your engine needs head studs and when it doesn't
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Registered:
May 2004
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Re: HEAD STUDS vs. HEAD BOLTS
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Tue, 13 July 2004 01:48
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actually there is one danger in using either studs or bolts
any substance in the hole in the block that they use
can cause hydrolock on a 22r/e
an amazingly tiny amount of lube in fact
as i found out wen i installed my studs
it duzn't haf to fill the bottom of the hole !!!
i wuz kinda shocked by this
probly just cuz it never happened to me before
peepl say a bolt with a groove cut into it lengthwise makes a good thread cleaning tool
on a 22r/e you always got that dry hole by cylinder #3 on the exhaust side
that's a hot spot, right?
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On Probation
Location:
North East NSW
Registered:
December 2002
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Re: HEAD STUDS vs. HEAD BOLTS
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Tue, 13 July 2004 01:59
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| toynado wrote on Tue, 13 July 2004 11:48 |
peepl say a bolt with a groove cut into it lengthwise makes a good thread cleaning tool
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this is true, aquire an old head bolt and cut down it with the angle grinder, wind it in and out a few times, cleaning in between passes. however if i was spending several hundred dollars on head studs, i wouldn't mind spending another 10 bucks on a proper thread cutter from a fastener shop, which will do a better cleaner more precise job
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