It appears I stretched some ARP head studs...

[donniekak]

I have my L19's torqued to 115 ft/lbs. 30/60/90/110/115 torque sequence. I did have two L19's stretch during installation once, and ARP replaced them free of charge Next Day Air.

I did torque-check my head studs two times after installation after several heat-cycles.

I was also using ARP ultra-torque assembly lube and a Mitsubishi MLS head gasket. Holds my current peak of 52psi no problems.

Have you ever noticed any smashing/distortion of the washer seat area of the head?

 

[BigBeans]

Are you still running ethylene glycol-based anti-freeze or are you running water with Water Wetter and a small amount of anti-freeze?

The 170-degree T-Stat will definitely help.

It was a little more water than anti-freeze, maybe 3:2, and half a bottle of Water Wetter.

It's not my DD but i do use it as a street car often, so with the sub-0 temps we've had lately, i didn't want to use too much water. The next mix will probably be 2:1 (water : anti-freeze)

 

[DSMopar]

I don't work in fastener manufacturing. Until i spoke with someone who did, i had no idea what the expected variance between batches was.

I don't either, but you had an M.E (the kind that designs shit like this) telling you otherwise

I said in the opening post that the only reason i resorted to measuring them against a new set was because i can't find a spec for length...

Well now you know, don't do this anymore.

The ARP tech guy knew the power output of the car, and said even slight detonation could stretch these studs at this power level. Do you really expect me to take your opinion over his?

Ya the ARP tech. Do you understand what a 'tech' is? They're typically non-college educated individuals that sit and answer phone calls all day with limited knowledge. He might be able to find you specs from their data-base and give you general advice, but I wouldn't be asking him a serious engine question. Why don't you call back and ask to speak with the engineer that designed those studs (they won't because that's why we have the 'techs' to deal with the general public). So do I expect you to take my opinion, maybe not considering you thought you stretched your uber-headstuds, but you should.

Let's think logically for a minute. As i already posted, there's coolant residue in all 4 intake runners. That means a crack is basically impossible, and the head gasket would have had to leak across the entire length of the engine. I'm not sure how that could happen with adequate clamping force...

You know it could be anything, you've done absolutely no diagnosis whatsoever. Lets start with the basics, where is your air filter? In the engine bay? Did it cross your mind that whatever the source of the leak was (hose, cracked block, cracked head, blown headgasket) could have provided coolant for your entire engine via the turbo inlet? Speaking of turbos are you using a factory style turbo IE one with coolant running through it? Or you can just assume your infinite automotive intuition is correct and you're making such crazy HP that you must... MUST have stretched your aftermarket headstuds (but didn't blow the gasket).

 

[MY1GDSM]

Have you ever noticed any smashing/distortion of the washer seat area of the head?

I'm curius to know this as well ^

Its seems at those Torque levels that the Studs may not stretch. But, that the head would/could mushroom or cut into the head under the studs washer... .

I've seen a couple heads that had been over zealously torqued to over 100lbs that looked this way...

 

[BigBeans]

I'm curius to know this as well ^

Its seems at those Torque levels that the Studs may not stretch. But, that the head would/could mushroom or cut into the head under the studs washer... .

I've seen a couple heads that had been over zealously torqued to over 100lbs that looked this way...

I also have this question.

I'm going to 105 tmrw, i'll post if i have any issues.

 

[ed1380]

I'm curius to know this as well ^

Its seems at those Torque levels that the Studs may not stretch. But, that the head would/could mushroom or cut into the head under the studs washer... .

I've seen a couple heads that had been over zealously torqued to over 100lbs that looked this way...

can we get an answer to this question please.

 

[BigBeans]

can we get an answer to this question please.

I didn't have any issues @ 105lbs, but that wasn't really your question. I haven't looked at this stuff in awhile, but i think you can go to a slightly higher torque spec with ARP Ultra Torque than the old moly lube.

 

[ed1380]

I think it should be the other way. the newer stuff is a better lube therefore needing less force applied.

like for normal arp studs, you need to use 130ft/lbs with normal oil and 80ft/lb with moly lube

I would also be afraid of the head being damaged, but the people running 50+ psi have to hold it down somehow

 

[BigBeans]

I think it should be the other way. the newer stuff is a better lube therefore needing less force applied.

like for normal arp studs, you need to use 130ft/lbs with normal oil and 80ft/lb with moly lube

I would also be afraid of the head being damaged, but the people running 50+ psi have to hold it down somehow

The newer stuff doesn't need less force. Some sources say use the same amount of torque as moly, but IIRC the tech i spoke with at ARP said the new lube actually requires slightly more torque than the moly (as in a few lbs, not a considerable difference)

 

[defrag010]

What I missed when I read this thread is the lack of teardown information. I personally think you can pinpoint the cause of failure exactly almost every time by how the motor comes apart. This is the most overlooked part of wrenching on cars: everyone just just tears it apart and then inspects everything.
The teardown of a test/mule nascar engine at a nascar shop is almost, if not more, involved than assembly. Every spec is recorded, and even though the engine might have been running fine, they use the data from teardowns to determine what needs to be changed to prevent a possible failure.

What was the breakaway torque on the head studs when you took them off? A telltale sign of a stretched stud is less breakaway torque on the failed stud than the others. Also, when measuring studs for stretch, measure comparatively with the other used studs from the engine (same batch of studs) and look for any differences between them.. comparing to new studs will get you nowhere.

 

[99gst_racer]

What were the standard ARPs torqued to? And what lubricant was used?

Comparing lengths of stud to stud is useless because they will all vary some in manufacturing. The only way to determine permanent stretch is to measure and record the freestanding length of each stud prior to use, and then compare the freestanding length of each after use.

For 12mm (6-bolt) L19's, I'd recommend 105-108 ft/lbs max (using moly lube). And torque specs don't change for moly lube vs. ultra torque. The only advantage/difference of the ultra-torque is that it offers a more accurate torque spec without cycling.