Bookshelf

You loosened them before you retorqued? Any reason for loosening? I always thought retorquing something just meant going back over it to account for gasket contraction, heat cycling etc. Looks very nice under the hood btw.

BC847

Even with prior application of ARP assembly lube, the torque required to get things moving or more commonly called "Break-Away Torque", can be more than the final figure you're shooting for.
In this application, 125ft/lbs is the final torque target. With doing nothing else, it's possible to have to pull perhaps 150ft/lbs (for example) to get the nut to move. As such, you've over torqued the thing. Till now, I've just backed the nut off about 1/16th of a turn, and then pulled it back to 125ft/lbs.

But . . .

I've recently talked with an engineer at A1 who explained that I really need to reapply the assembly lube each and every time the stud/nut is torqued. Being that he dinks with hundreds if not thousands of potential applications of their product, he was not really familiar with our re-torquing our mess and why (O-ring/Gasket crush) including the "Hot Re-torque". He found it odd and mentioned the NASCAR series engines running studs might be torqued three or four times tops through out the life of the engine (Initial assembly, Torque honing, Final assembly, etc).
Stud/Geek comes to mind. I could tell he was into it as he was steady digging through spec sheets for the studs and comparing my applied 125 ft/lb figure. "Uh huh, . . .. yes . . . . ooh! that's a lot. . ... . OK, that will work " (calculator whirring in the background).
Further, he made a point of explaining that the general re-torque procedure isn't necessarily to ensure the proper loading/stretch of the stud exclusively. For example, it also goes a long way in ensuring the nut is properly seated on the stud thread-wise as there's some burnishing action going on with the torquing. Such burnishing helps assure full thread contact between the stud and nut so as to fully realize the unitary strength of the stud/nut assembly.

With that, I plan on a not too far future hot re-torque to include re-lubing it all before pulling it back up. That of course will entail removing the nut all together (individually of course).

Bookshelf

I understand the importance of the lube and friction affecting the final torque value, but when do you get to the point where you've stretched and relaxed the fastener too many times, and does the unclamping/clamping have any effect on the gasket, even if you're doing one at a time? Also when you were chasing the threads in the block, did you use a standard size tap? I've seen taps specially made for chasing threads as to not remove any more metal. This is the first write up on a head install/retorque I've seen that goes into this much detail, probably why I'm asking

BC847

I don't know that there is a point where one could wear out a bolt with too many torquings provided one doesn't go too far and dip into the plastic zone. Once there, if only a itsy-bitsy bit, the fastener is done. It's kinda like being a little pregnant. It's my understanding though that the region of stretch narrows somewhat with repeated working. I've not seen any suggestion that repeated torquing can be detrimental to the gasket. Perhaps there is some crush going on with the O-rings and fire-rings with radical work (super late-model NASA 14mm stuff running 175ft/lbs and up).
As far as the block bores go, I used a standard bottoming tap. They typically present as any other tap but only the first two threads have any taper. The reason for bottom tapping the block isn't so much for the threads to be right as it is to ensure the stud actually rests in the very bottom of the bore for overall height purposes (as in the case of the A1 studs).

I'll most likely come up with a "How To" for studs, oil cooler, coolant adjunct, and possibly a general head/head gasket replacement primer. I dunno. I've got images of it all, just got to get to it. .. .

Alwaysworking

David, you wouldn't happen to have a picture of the back side of the heat exchanger/ oil cooler? when its out of the block?
Thanks Thomas

BC847

Talk'in about this? . . . . ..



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I'm lead to believe that some trucks have a five plate exchanger and others have a seven plate unit. The FSM suggest there's no performance difference. That I do not believe. More heat exchanging surface area by default implies a higher quantity of heat exchanged.

Alwaysworking

Thank you sir, thats what i wanted to see