Anyone know what the Torque settings/procedure is for the ARP head stud nuts?
I know the studs go in finger tight, but there's nothing on the ARP website about the nuts!
I have emailed them but thought i'd ask on here too!

Cheers!

 

You take them out and use them on a N/A car for which they are more suitable...

 

Why Rick?

 

You're not using them on your turbo engine are you? They aren't suitable, they vary their clamping load with time, and also aren't suitable for the high compression pressures in a turbo engine.

Rick

 

I had planed to yes!
Why are they not suited to high compression pressures applications, and what makes the clamping load vary over time?

 

Of all people, Karl, I would have thought you'd have known better!

Standard stretch bolts mate. Thats all you need.

 

Ford fitted stretch bolts for a reason, it always makes me laugh when people refer to them as though it was accidental!

 

lol
Well I know that all you big bhp boys use stock bolts, but they came with my recently purchased block so thought I might use them if they give a more even/reliable clamping force which ARP say they do!

I know why stretch bolts are fitted and from what I have read so long as stud/nuts are re-torqued after say 500miles they should not cause any problems!

 

Ford fitted the lowest costing bolts that would survive the intended application. High grade steel and rolled threads cost alot more - and were avoided purposely. ARP type bolts are infinitely superior to factory stretch bolts. However, factory stretch bolts do perfectly fine in many applications. The Ford CVH head (and its poor flow compared to modern 4 valve designs) limits power output, thus factory stretch type bolts may be successful. I however choose not to use factory hardware - head bolts and main cap bolts. Why spend $10,000 on an engine build and use 10 cent bolts?

Torque spec for ARP bolts is 60 ft. lbs. with ARP thread lube.
Retorque bolts after engine has been warmed up and cooled.

 

Rick, can you elaborate?


I've never saw a problem with ARP bolts on turbo engines? seems a bit odd...

 

It's to do with dissimilar materials. Stretch bolts accomodate the block and head heating up and cooling down at different rates.

Canada1, spending more doesn't always mean better. I fitted an MHG and ARP's, was the first and only head gasket I have ever blown. I went back to stock gasket and bolts and never had a problem thereafter.

The problem that I had and I know Karl's lot have had the same, is that the head lifts at much over 350bhp. IMO, that is more down to it being the physical limitation of the SIZE of the bolts and going to ARP's won't help.

Karl, if OEM bolts are good enough for me/Tim/Oli and probably (I would guess) Stu Collins, then why aren't they good enough for you??!!

 

When your Cometic head gasket failed - I believe it was a result of head and block surface finish being the cause - and certainly NOT the ARP head studs. The surface finish required for Cometic head: "head and deck surfaces be flat within 0.002 inch and have a 50RA-or-finer surface finish"
I do not recall you resurfacing the head and block deck before using the MLS gasket ( I could be wrong).

You mention the heads tendency to "lift" over 350 HP - the physical limitation of the bolt.
The ARP studs have a much higher yeild strength - how could they not be a benefit over factory stretch bolts?
The factory stretch bolts are stretching beyond their yield strength.

 

They are good enough for me!
As i said they came with my block so thought if they are any better at all at spreading clamping load then I will use them! If they are not, or they will cause a problem then I wont!

But IMO the head and block shrinking and expanding at different rates is irrelevant as long as the clamping load is correct for that application, and keeps the head/gasket/block seal intact as it should

That is not what stretch bolts were designed for.

 

Canada1, whilst your theory is sound, in practise it is simply not the case. I have seen numerous failures using the ARP bolts on the CVH. The std head bolts and gasket just don't fail. I have never seen a CVH turbo gasket fail that wasn't caused by overheating, detonation or some other abnormal condition.

Rick

 

Hi Rick,

The failures using ARP bolts are the result of incorrect procedures - not the fastener.
Why would Formula 1, Nascar, and other professional series use ARP studs for engine assemblies if they were inferior? That is just silly. The metallurgy is simply superior.

The reason stretch bolts were introduced by mass manufacturers was to eliminate the
retorquing that was necessary with a non-stretch fastener and easier for automated engine assembly . Do you realise how a stretch bolt is designed to operate? It is made of a lower grade material - grade 8 or lower, and is torqued over the maximum yield point at which the fastener reaches a plastic stage. There is alot of published material on the subject.

Again, for some applications (lower stress) the stretch to yield bolt is perfectly fine.
Putting in a better fastener may be overkill, as are forged pistons and steel rods, but
for that extra insurance and a much longer mean time between failure.....

 

I have cometic head gasket and arp head bolts, amongst other mods (will post if required). I'm running just over the 200bhp mark and never had any issues.

For the record I torqued the bolts to 66psi and then another 90 degree turn

 

What was the reason for the failures though Rick, do you know what had actually failed, had the gasket let go, was it not sealing because of inconsistent clamping force, etc..?
I'm trying to make a decision and learn based on actual technical information (rather than 'They are bad... end of!' lol ) so am very interested to know!

Yeah thats right.
We are talking about ARP head studs/nuts not ARP head bolts mate, two different things.

 

Karlos, it's ultimately your choice, but for someone that has already had an engine failure, it seems odd that you're prepared to take the risk, when you know for sure that OEM bolts will be fine.

I don't understand why the guy above torqued his to 66lb, then 90°. Angles are for stretch bolts, no? That extra 90° might be 50lb more torque on the bolt? Riiiiiisky IMO.

 

Also, was there not an aspect of the stretch bolt that was used to take into account the type of head gasket? The standard head gasket is more compliant than a MLS one, so maybe the bolts need to conform to that?

Either way, we know standard works. There have been very few cases of failure at the upper end of the scale, as testified by me/Karl/Tim/Rick etc, but plenty of cases of head gaskets failing when MLS/ARP are used.

I hope I don't have to dish up an 'I told you so!!'

 

hehehe no you wont!
I have no problem using standard bolts and that is what I will use as i'm not prepared to take the risk!
But I like to learn as much as I can! So if someone says stud conversion is no good I want to know exactly why, and so far no one seems to know other than saying they have had failures, which could be down to any number of things.

I think the guy above was talking about ARP head bolts not studs/nuts when he said 66lb then 90°

Gasket compliance is one of the reasons Ford use stretch yes, but if you re-torque stud/nuts after a few miles it's not a problem.

 

Hi Christian,

The reason ARP failures probably happen is shown in Lurch1977's post:
"For the record I torqued the bolts to 66psi and then another 90 degree turn"

I am stunned someone ( or some shop) would know more that ARP regarding the torque
procedure for the head studs. 66 ft. lbs. ( I assume - what has psi got to do with anything?) and then another 90 degrees - this is insane!!! That ARP stud is now garbage.

I guess it would be best to suggest standard Ford stretch bolts for the masses.

I am still quite stunned and now speachless.

 

my mate put arp studs and nuts in his civic vtec turbo and when he tightened them down to arp's torque setting which where on the instructons 1 of the studs snapped and that was using arps exact torque setting and a snap on torque wrench before anybody says the wrench was wrong canada1 must either work for arp or have shares in them to really care what anybody else is using lol
each to there own imo tho lol i should really not come on here after a few glases of wine

 

Hi Matthew,

I do not work for ARP.
Each to his own.
The stud that snapped was probably overtorqued previously - go have another 3 bottles of wine.

 

Its odd that providing ones experience - (I don't just pay someone to build my cars) - gets so much ridicule - what is with some of you?

 

they where brand new unless arp sell used studs and nuts??

and dont worry im on the case

 

That is fine, as you state, each person is entitled to their own opinion, but with so many high powered 1600CVH's on this forum we do have a fair bit of experience of what works.

I know my RST was absolutely reliable on OEM gasket and bolts and survived through the failure of each of the ancillary water hoses one at a time without taking the head gasket. That, to me is testament to the OEM setup and beggers belief why anyone running to run significantly less power than I did would want to use anything else.

The whole world believes MLS gaskets are the way, just as they believe that poly-bushes are the way for suspension too, but I happen to think they are shit also. There are applications that do well with MLS gaskets and ARP bolts, but I just don't think the CVH is one where it is needed.

I spoke to Karl a few years back about the issue with the head lifting and he discussed redrilling and fitting over-sized studs, but he was quite rightly sceptical about this, as nobody knows what it will do to the integrity of the block. I have never heard anything of this mentioned again, so either it was sucessful and they are keeping it close to their chests (understandably), or they put it down to experience. None of us have discussed in detail our tribulations with significantly passing the 350bhp mark, but I am fairly sure that we are all in the same boat and dropping out one-by-one as it is more trouble than it is worth.

Stu Collins has made roughly 350bhp, it will be interesting to see if he runs into the same problems when trying to go further. It is also interesting that the route Karl appears to have taken with Tim and Oli is an oversize taking the capacity to over 1700cc's. I have no facts to support this, but I think I'm right in saying that? Maybe this was done to give a little bit more power, without the higher cylinder pressures. Who knows.

Bottom line is, if it ain't broke, why fix it?

 

theres alot more to it than just fitting new studs
there is alot of preparation to use them in an engine

 

The 66 lbs ft then a 90 degree turn were the settings given by ARP

 

such as??

i always clean my threads first with a tap before i install any head bolt or stud ive used arp studs on 2 engines once on the civic turbo as mentiond which snapped the bolt and once in my zetec turbo so if you could point out where im going wrong??? i also make sure there is not trace of water or any debris in the bolt hole as we all know that water cannot be compressed