billindenver

It has been suggested that I post this in a thread under this heading because the discussion is buried in another thread.

A couple of us now have had our new ARP's stretch, or I should say we are assuming it is stretch. Here is my experience anyway.

Had the motor out so ARP's fell under the 'while it is out, I might as well...' category. Head and block were both milled flat at P-car machine shop. ARP's were installed per instructions and a month or so later I started experiencing coolant loss. After looking for leaks etc, I decided it was the headgasket. When I pulled the cam tower I put a torque wrench on the head nuts and found each of them nearly 90 degrees of twist until 65 ftlbs clicked off (original torque). The headgasket is not blown in the typical sense of how they go, but you can see where combustion has escaped into the water jacket as the water jacket is bowed a bit (not flat) in that area and hard as a rock while the rest of the gasket is not.

So I called EBS and asked them about this after another poster said he is experiencing the exact same thing (again, newly worked head and block so it's not a prep problem). EBS said they have never seen this before, but suggested that after 1000 street miles or so I try re-torquing the head as that is what Raceware's suggest.

What a pain. I never had this problem with the original stock head studs and was running 22psi on those for 10 years (have not turned it up that high on new rebuild yet). The other poster was running 15psi on his and this happened so I don't believe it is a boost issue. I bought the ARP's as insurance since the motor was out anyway (Grrrr). Has anyone had the ARP's stretch on them? Was it just an initial stretch after which they are solid? Are you using 65 ftlbs of torque as your final step? Your thoughts would be appreciated.

87944turbo

Just out of curiousity, what are ARP's instructions for installing the studs and which HG were you using?

KuHL 951

Not sure if it matters but Tony G. says that ARP and Raceware 'no-stretch' studs just don't work well on the 951 open-top block and 'stretch to yield' OE style or custom studs are the way to go. Others have had years of good luck with ARP and Racewear. I'll certainly be watching this thread closely as I haven't opened my box of ARP's yet.

billindenver

ARP's instructions state put them in with red loctite in block, torque to 25/45/65 in steps and you are done. This is all from memory as I'm at work at the moment, so hopefully I'm not to far off. My headgasket is typical wide fire.

David Floyd

I torqued my ARP's in steps 35lbs, 55lbs and 75lbs, let set overnight then recheck @ 75lbs (no change) finish assembly, no retorque after run in.

The overnight set was per ARP phonecall.

Cometic MLS gasket, no problems after 4+ years and 40k miles

KuHL 951

Is they additional 10 pounds your method for all HG types or ARP's instructions 4 years ago? Thanks

Ski

+1 as David, although not as many miles. I used an old gasket to let them sit overnight, then replaced with new, torque in 3 steps.

Pauerman

I just installed ARP studs and Cometic MLS gasket on my resurfaced head and cleaned block. I had coolant seeping around the perimeter of the head gasket just from motoring the engine for building oil pressure.

I called EBS to inquire about the 65 lb/ft torque spec and was told that sealing a Cometic gasket can be hit and miss. They recommeded I try torquing hardware according to factory instructions - 15 lb/ft, 90,90. After calling Cometic, they claimed that 65 lb/ft was more than enough torque and that I should remove the head to inspect mating surface.

I ran the engine with seeping issue for the initial 15 min run-in. After the heat cycle, there was no more seeping. I ended up retorqing the nuts to 85 lb/ft just in case and I haven't had any issue yet. I'm still breaking in the engine and don't have any further coolant seeping issues.

tyro

Bill,

FWIW, I called my friendly engine builders, they told me this:

Composite gasket= recommended re-torque
MLS gasket= no re-torque required

He did mention a drag Mustang that was using up head gaskets after every third run. The owner switched to an MLS gasket and hasn't had an issue since.

Wormhole

Where did you guys buy the ARP? I can only find raceware from the vendors.

billindenver

EBS racing

http://www.ebsracing.com/

Tom M'Guinn

I've used Racewares for several years now. I had a hard time at first with various tuning issues, and so had to change the gasket several times. I initially followed Raceware's instructions and torqued to 65 ft lbs and retorqued after the first heat cycle. I found that the nut rarely lost their torque after one heat cycle -- it usually take a few hundred miles. More often than not, it's ok, but sometimes they do get looser. I don't believe the studs are stretching, but rather the gasket is getting thinner. Second, I generally torque the nuts to 85 ft lbs or so. This gives you room for cushion if they loose a little torque, and adds clamping force to prevent lift. I spoke to Scott Gomes about this a while back and apparently I'm in good company doing it this way.

Presume all the same applies to ARP....

billindenver

So you are torquing to 85 and not retorquing?

Tom M'Guinn

Well, actually, I torque to 85 and then retorque if/when convenient. I did retorque the last time after maybe 500 miles or so, but none of the nuts moved a bit if I recall.

billindenver

The more I think about this the more sense it makes. The stock studs are stretch type, so you stretch them and when the gasket compresses after heat cycles....the stretch keeps force on the gasket pretty equal. Non stretch like ARP's and Racewares will not do that. MLS gasket may not compress like the stock one...so no need to retorque. I guess I should have thought about this earlier, would have just bought new stock studs rather than go through the retorque BS. No time to go MLS and make this weekend's event so putting in another stocker, maybe it will make it through the weekend without blowing my coolant out like last time. I'll leave the boost turned down to moderate levels this weekend.