[HamsMKIV]

Hey guys.

I've searched around a bit and I've found widely varying numbers on the proper torque spec for ARP head studs. I've seen everything from 75 ft/lbs. to 100 ft/lbs., and the variances in numbers makes me question whether or not I've properly torqued my head... I just completed a new motor for my car and I used a Titan Motorsports 1.4mm MHG with the ARP head studs, but I only torqued my head to 80 ft/lbs.... Perhaps I should have torqued it more... I am really wondering now...

- Hams.

 

[drjonez]

you should be fine.

 

[conundrum07]

You will be fine. I did 85 on mine.

 

[GrimJack]

IIRC, the higher torques are for steel blocks, the lower ones are for aluminum ones. I thing ARP just publishes generic instructions for all their head bolts.

Pardon the quote, but, "they are less rules, and more like guidelines."

 

[paddlenbike]

I believe my ARP bolt set (not stud) had a range up to 115 lbs or so, depending on what lube was used on the bolt.

Personally, I used 83 ft lbs with the ARP lube because it seemed like a perfectly reasonable random number. I finally took that number out of my sig because I was getting too many PMs asking how I chose 83. Maybe that's why my car has been 100% reliable for the past 1.5 years. It's all about 83 ft lbs... :lol:

 

[outofstep]

I depends on what you lube with. If you use there crap the range is high 70 into the 80s. If you used oil then its ~100. It says this right in the instruction booklet.

For whatever reason I didn't have the lube so I used oil. I torqued down to 90 something.

 

[p5150]

if you dont have the lube you can always purchase a tube of engine moly-assembly lube from checker, shucks, etc for about 3 bucks.

I think you will be perfectly fine with 80ft lbs. Unlike a bolt which encounters resistance along the entire length of the thread, a nut on a stud only rubs on its seat and the ~1 inch of thread that it has. Thus, even with proper lube a nut will exhibit more clamping force than a bolt at the same specified torque.

Molybdenum is the metal that they put in the thick lube - its a soft leadlike substance that acts as a lubricant under high pressure. Rather than some of your torque being lost to the friction of the seat of the nut and the threads, more force is applied from the same amount of torque because the moly keeps the metals from "grabbing" each other.

Hence the reason for higher torqe values when using a motor oil. Motor oil loses some of its lubrication properties at higher pressure, so a higher torque value is required to exhibit the same amount of clamping force due to the friction of the seat and threads.

I think you are good to go. Once your motor has broken in, at about 1k miles, remove your valve covers and retorque your head nuts to about 90 ft/lbs (just because the lube will have worn out) while you reset your shims to the correct clearances.

 

[DaleH]

So 90 ft/lbs with ARP studs with HKS 1.2mm HG? That is not to much for the head?

 

[HamsMKIV]

I used the moly lube supplied with the ARP head studs and torqued them in a 5 step sequence, 15, 30, 45, 60, 80. I was just concerned that 80 might be too low for a MHG since I've seen alot of others who torqued it higher. I'll definitely verify torque at 1000 miles and watch it closely. So far it seems terrific and no complaints.

- Hams.