Headwork question

[jetdc2R]

hey

Question: hey guys, just wondering if you pull off a head off a motor to do head work do you have replace headbolts??

cheers

[jetdc2R]

bump.

[zeni-tani]

I believe if its no longer as p/factory spec it will need replacing, however it is a good mechanical practice to replace them specially when the engine has coverd high K's with frequent beating.

Diffrent story if you have ARP head studs.

[jetdc2R]

What will happen if i dont replace the bolts??is there a possibility oil will piss outta where the head and the block meet where the head gasket is??

[bennjamin]

the bolts , will stretch. When you retorque the head , they can over stretch / weaken / open up gaps etc.

Just use new ones.

[zeni-tani]

Well is crucial since its responsible for fastening the head/block. And head bolts tend to stretch over the time, from memory there not that all expensive to get some OEM replacements 50-60bux.

To be honest for peace of mind just get some new ones so there will be no problems.

[jetdc2R]

thought soo, honda charge $22 each bolt, and 3 week wait..

does anyone know a place that will have in stock??

[dougie_504]

Go for ARP head studs. They're pretty much the standard when modding the head and are good for frequent 11,000 RPM driving. The build material is supposedly "far superior to aircraft quality"

[jetdc2R]

who sells these head studs??can u name fue places so i can have a look.

cheers

[rage_against]

http://cgi.ebay.com.au/ARP-HEAD-STUD-KIT-HONDA-B16-B18_W0QQitemZ350319819799QQcmdZViewItemQQptZAU_Car _Parts_Accessories?hash=item5190b03c17


or try digging around in the traders,

like here

http://www.ozhonda.com/forum/showthread.php?t=89815&highlight=head+studs

[TODA AU]

hey

Question: hey guys, just wondering if you pull off a head off a motor to do head work do you have replace headbolts??

cheers

No, not always...
& there is no set requirement to replace them at overhaul...
All that is required is to check the length...
So, check the OEM manual... Measure the length...
If they're OK, re-use the original head bolts... :D:thumbsup:

If they're out of limits, replace them with OEM bolts or aftermarket studs (eg: ARP)
& good 2nd hand ones are OK if you're on a budget...


Remember... Prophylactic use of over engineering will burn a hole in your pocket with no real net gain...
If you want to build a car & babble on like the nutter who built "Jurasic Park"... Bla bla bla... "Spared no expence!"
Then that's fine...
Otherwise, just follow OEM requirements for overhaul & reuse of std parts.
Hope that helps.

[jetdc2R]

No, not always...
& there is no set requirement to replace them at overhaul...
All that is required is to check the length...
So, check the OEM manual... Measure the length...
If they're OK, re-use the original head bolts... :D:thumbsup:

If they're out of limits, replace them with OEM bolts or aftermarket studs (eg: ARP)
& good 2nd hand ones are OK if you're on a budget...


Remember... Prophylactic use of over engineering will burn a hole in your pocket with no real net gain...
If you want to build a car & babble on like the nutter who built "Jurasic Park"... Bla bla bla... "Spared no expence!"
Then that's fine...
Otherwise, just follow OEM requirements for overhaul & reuse of std parts.
Hope that helps.



what if.. my head was taken off..then put back on with origianl oem bolts..then realised there was a problem when it was started first 20 seconds...then head gets taken off again can u re-use the same oem bolts or there wrecked??

[TODA AU]

what if.. my head was taken off..then put back on with origianl oem bolts..then realised there was a problem when it was started first 20 seconds...then head gets taken off again can u re-use the same oem bolts or there wrecked??

There is no set requirement to replace them every time.
Just re-check the length, confirm this in the manual.
If they're within limits, you're clear to re-use the original head bolts...

[bennjamin]

what if.. my head was taken off..then put back on with origianl oem bolts..then realised there was a problem when it was started first 20 seconds...then head gets taken off again can u re-use the same oem bolts or there wrecked??


interesting question -

Are the head studs stressed through initial torquing , or is it a service life that places stress ( stretch) on them ?

[dougie_504]

Surely the hard use of the engine would play a part, and probably if somebody over-torque's them?

[A-man]

initial torquing is what stresses the bolts

because torque is stretching the bolts, which creates the stress this is why the bolts get tight because its being forced to turn into the thread, however the head of the bolt is stopping it from proceeding so therefore the bolt either has to stretch or break the threads.

now over time due to heating and cooling, and due to properties in the steel. the bolts will start to 'remember' the shape, this is why when you pull the bolts out,they will be longer.

its got nothing to do with overtightening the bolts or misuse or the apprentice doing it etc. its just the way of the world.

and toda is right. i also like the arp studs because there studs and you dont stress the threads on the block as much as you do with bolts.

the way i understand (installing them by hand) then fitting the nut to the stud and tightening the nut the torque is even on the stud and the bolt on either end of the stud, producing the same torque on the head, but without overtaxing the block threads and the stud threads

[Lerlo]

So when assembling a head, is it alright to just use a torque wrench? Ive read that you require a bolt stretch tool to be safe.

[A-man]

just use a torque wrench ive never heard of a bolt stretch tool before. r u sure someone isnt giving u a bum steer

[Lerlo]

just use a torque wrench ive never heard of a bolt stretch tool before. r u sure someone isnt giving u a bum steer

I dont know whats it called but it measures how much the bolt stretches as u tighten.

[string]

I dont know whats it called but it measures how much the bolt stretches as u tighten.

You were correct. You use it because torque measurements are bogus. The only accurate measure of how much stress you are putting on the bolt is by measuring the strain. Plastic deformation (permanent stretch) happens when you go past the yield strength (i.e. the maximum clamping force you can achieve and have the fastener completely return to normal when you undo it).

You can't measure the length of the head bolt/stud as you install it, so you must do the best you can with the torque method. Clean threads on both block and fastener, correct thread lubricant, steady technique.

Please borrow a text book from your local library if you want to learn about tensile strength.