dieselfan

[quote=HOHN;2158508]If you are using the regular ARP2000 studs, I would go to 125lb-ft with 30wt oil, or 100lb-ft with ARP lube.

If you are using the Custom Age 625+ studs, you can go a good bit higher-- they have unreal fatigue capability and they are over 260,000psi without being brittle or prone to stress corrosion and hydrogen embrittlement like H-11 and a lot of other "high strength" steels are.

I'd take a 625+ stud to 125 on ARP lube, 150-160 with 30wt oil.

I have no idea what guys are doing with the 625s, or what the "official" spec is, but that's what I would do.


why do you go higher with 30wt vs arp lube? can i use 15-40w instead?


thanks

HOHN

You go higher with motor oil because it's not as slippery as the ARP lube under extreme pressure. This means that the nut will be tighter for the same torque-- or more accurately, the bolt will be stretched tighter for the same torque spec.

Keep in mind that you're trying to stretch the stud like a spring-- so the tq spec is just a means to that end. We can't easily measure stud elongation, so tq spec is about the best you can do. Unless have the ultrasonic tool to measure stud length to high precision.

That's why for connecting rod bolts you'll often see the length measured rather than a tq spec used-- it's far more accurate, and the rod bolts are usually the most stressed fastener in any engine.

Justin

dieselfan

ok thanks. would a synthetic be better?

HOHN

Just use the ARP lube if you have some. Or any dino oil will be fine-- just go a bit higher on the torque.

I dunno about syn-- it's gotta be between the two somewhere..

jh

dieselfan

ok thanks

Mike Holmen

Crank with ARP lube to 135 ft*lbs, trust me. A high end oil will work as well.
I do line retorque, one at a time. The mark the fasten is just see if the stud is still moving/turning, which effects clamping force. If you have o-rings, do the re-torque often until things stop changing and become repeatable. If you're running a stock head, I would still torque the studs up to 135 ft*lbs. If the stud about to break, you will be able to turn it about 1/8 turn with almost no force, then its will break. You can tell as it will get easier, and it will ruin your day. Torque the retainer to 135 ft*lbs is a good workout.

HOHN

Mike I'm assuming you're speaking of standard ARP2000 studs...

How high would you go with the 625s? These are pretty amazing from a metallurgical point of view..

jh

Mike Holmen

Rumor mill says 155 ft*lbs for the 220ksi studs. I haven't tried them yet, just stuck on the old standard ARP's. PDR told me to goto 135 ft*lbs after I blew my head gasket. I just did mine last weekend. Still trying to get a decent hold on the gasket with the o-rings. Takes about three to four good re-torques before you should really put your foot into the firewall.
You should re-check your lash on your valves after you do a re-torque as things do move some. I sometimes miss that step depending on my schedule. I had a few old ARP's studs on the exhaust side that the coating came off and they where unable to be torqued up properely.