Proof Headgaskets Need Re-Torqued (Data Inside)

[Stinger]

I've seen in the past that people claim the 8993 gasket isn't as critical to re-torque as the 1035.

I installed an 8993 on my SVO and torqued it to 65ft/lb with arp studs/lube. Warmed it up to 202 degrees and shut it back down. Once it had cooled back to room temp, I began the re-torque process.

I measured the torque that was required to loosen each bolt with a mechanical torque wrench (handle bends to show torque).

Outer studs took 45-50 lb/ft to break loose.
Inner studs took 38-43 lb/ft to break loose.

I also checked by simply putting the torque wrench (set to 65 lb/ft) on an untouched stud and it moved ~3" before clicking. Since it takes more torque to "break away" the nut and get it moving than it does to keep it moving, this was a pretty shocking result.

After all the studs were re-torqued, I checked the torque required to break a few loose once properly torqued and got a result of 58-60 lb/ft.

I plan to do the same test one more time after I drive the car a bit. Curious to see if it needs more than one re-torque or not.

These results are with an aluminum head. Matt says he will do the same test on an iron head soon.

[oneowner88lx]

Interesting. I torqued my head bolts to 90 in three steps 50, 70, then 90 using the factory sequence for each step. Put ARP lube on there too so they are probably tighter then they are supposed to be.

[Stinger]

With an iron head it is ok, ARP says to torque them to 80 with moly lube though, not 90. Either way, if you didn't re-torque, they are looser than they should be.