Head Studs
 

I am curious to know if anyone has a confirmed limit to the factory head bolts. I am in the middle of prepping a VVT motor for my car. i am doing a head gasket and didnt know if arp head studs were really necesary for my goals. Stock bottom end, so i will be keeping it under 250wtq.

:dunno: I don't hear often of the heads lifting or bolts stretching...

I'd call it a "while I was in there" job and still put them in if you can afford it.

Not needed at all. Spending that $120 on rods or whores would be a better use of the cash.

whores it is!!!

I think stock bolts are good for somewhere past the 400hp / 350ft-lb mark but most people putting those numbers out put ARP in anyway because they already spent way more than that on there build and the added cost is negligible in comparison.

yep, and because stock bolts technically shouldn't be re-used

I always assumed this, but the FSM doesn't actually mention them as being TTY. I have reused them with no ill effect on stock-output rebuilds.

With boost added, consider the rest of the cost of your setup, then ask yourself if you want to be the guinea pig who finds out exactly where the limit of stock head bolts are. :)

Why? They're not torque to yield bolts. They're reusable.

really?
I stand corrected tehn

Stock head bolts can be reused, if you're confident they were installed properly and were not stretched into the plastic range by overheating the engine and warping the head. They are not TTY, the FSM is quite explicit about which parts need to be replaced and the head bolts are not tagged that way.

--Ian

The stock head bolts are probably stronger than the head. ARP studs can easily provide more clamp load than the head can stand. Torquing ARP bolts to ARP's torque spec will crush your head and you run the risk of turning it into a paperweight by cracking the bosses under the washes. been there done that.

Is this really a thing? I just bolted my head down on my new motor about two-three weeks ago with ARP hardware, torqued in sequence order per the FSM, however I torqued them down in multiple passes, first pass I did 20ft/lbs then loosened them all in order per FSM removal sequence, second pass i did 40ft/lbs, then loosened, third and final i did 65ft/lbs and stopped.

Did I miss an important chunk of "common knowledge" in regards to these heads + ARP hardware?

The "common knowledge" is that ARP specifies 80 ft-lbs in their instructions vs. 55-60 ft-lbs per FSM. Use the FSM value. Also, the ARP washers have a smaller diameter than the OEM washers, so it's better to use the OEM washers.

The one thing I like about the ARP studs is the consistency of the clamp load. With the OEM bolts, you need to be meticulous about making sure the threads in the block are clean and lubricated to get a consistent clamp. Shouldn't be an issue when assembling freshly machined parts, but when swapping a HG down the road it might be.

FSM torque spec is Ok its its the torque spec ARP gives for the studs that is nuts. Higher quality threads, finer thread pitch and the fact you are turning a nut with ARP moly on it rather than a bolt means the clamp load you get is way higher than stock even at the stock torque spec.

you're fine. we all usually do 55-65

Yup. You'll see that inconsistency when you install the studs into the block. If you aren't chasing every thread with a tap/chaser, there's zero consistency in the stock head bolt torque.

When I used my first set of ARP studs in 2009, the instructions said 65lbs. I opened a box somewhere around 2011-2012 and the instructions suddenly said 80ft.lbs, which I knew to be bullshit. I torque to 65lbs in 3 steps (20-40-65).

you guys are great, thanks for all the information.

EDIT: As thanks i have now become a proud supporter.

I put in the arp studs because the head was already off. I think that's why 90 percent of us do it.

I think it's a good thing because it's more consistent than using bolts. You don't have to fiddle around in the bolt hole getting it clean and chasing the threads. They're just sitting up top, easy to clean and lube before you put in the nuts.

I have always torqued to about 60-65 ft lbs in three steps.