ARP head/main quick question

[turbo98eclipse]

When you install the ARP main studs or head studs, how come you don't torque the stud itself via the hex that's there?

It looks like everyone is just screwing them in and tightening by hand... i feel like the whole thing would/could back out.

--paranoid engine builder

 

[WeaselHack]

Same reasons you don't torque down your exhaust studs. The stud isn't going anywhere once you've properly torqued the nut. On a side note are you using motor oil or arp assembly lube?

 

[gringo72884]

The torquing of the nut is what properly sits the stud. Use Arp Moly, verify the threads in the block are absolutely clean (chase the threads if necessary) and screw them in by hand only. Then properly torque the headstuds in the recommend sequence and steps and you are golden.

 

[turbo98eclipse]

arp lube-- i went 20-40-60 with it... sound good?

 

[GIRman67]

the final torque needs to be 80ft/lbs not 60ft/lbs. On one of these threads it recommends to loosen the studs and retoqure at each step as well.

 

[3kgt2nv]

the final torque needs to be 80ft/lbs not 60ft/lbs. On one of these threads it recommends to loosen the studs and retoqure at each step as well.

correct and you want the final step to be the largest

I do mine 30-40-86

86 is what is recommended with the arp lube for the head studs

You want to break them loose at each step and re tighten to the next torque step.

 

[1990AWD]

the final torque needs to be 80ft/lbs not 60ft/lbs. On one of these threads it recommends to loosen the studs and retoqure at each step as well.

Well you probably wouldn't loosen and re-torque at every increment. It's probably a 25-55-80 lb-ft torque, then loosen all the caps screws, and re-torque 25-55-80 lb-ft. That's how Cummins does some of their engines.

p.s. don't quote me on the torque specs, just an example of the procedure.

 

[turbo98eclipse]

the MAIN studs need to be 80? not the head studs, the mains... that hold on the crankshaft..

i read in other threads that people were calling ARP and they were saying not to go over 60 lbs

for example--http://www.dsmtuners.com/forums/newbie-forum/170901-arp-torque-specs.html

 

[gringo72884]

Mains are 60ft and headstuds I would do at 86-90ft

 

[RvlutionMtrsprt]

Confirmed, 60ft/lbs with moly lube on the MAINS. This is assuming that you had the main line honed with the ARP's @ 60ft/lbs. The higher torque of the ARP's and/or the use of a Kiggly girdle will pull the main line out of round (in most cases that I've seen) and the hone is necessary.

 

[turbo98eclipse]

Well I purchased the motor already built, 2.3 stroker... so I'm assuming everything was done properly while at that shop... I just wanted to recheck the torque on all the bolts and studs

Thanks for the clarification guys!

 

[e85_4g63]

Don't forget that if you are using ARP main studs, you need to have the mains honed after installing them.

 

[turbo98eclipse]

Don't forget that if you are using ARP main studs, you need to have the mains honed after installing them.

Yes I'm aware... like I said I purchased the engine already built. Everything looks like a legit build was done... from the high temp paint to bse bearings and overbore. So I'm assuming everything was done properly (guy I picked it up from also verified it was) plus its running an eagle 100mm crank (doesn't the block need to be machined to accept this?) New, or very, very well cleaned main caps and everything.


Everything was torqued moly lubed and assembly lubed. Engine never run. We should be good to go!

 

[bjones18]

when you install the arp main studs or head studs, how come you dont torque the stud itself via the hex thats there? it looks like everyone is just screwing them in and tightening by hand... i feel like the whole thing would/could back out.

--paranoid engine builder

Friction is what prevents the stud from backing out and the nut from loosening. Torque on the nut is used to approximate the "elastic stretch" in the stud. Fine threaded fasteners are much more stable than coarse thread (smaller ramp angle).

Generally speaking you should not bottom the "head-stud" out in the hole. As the block & stud expand from heat, the added stress from at the "bottomed" stud could be enough to start a stress crack. The main bearing "webs" in the block (where the head stud holes end) are already highly stressed and can develop fatigue cracks. Threaded regions are a great place for fatigue cracks to start. The added stress from a bottomed stud in that region is... completely un-necessary.