Can I replace head studs one at a time?

[FastDriver]

The Goal: I want to accomplish three things:
1. Achieve proper head torque for my application (high boost 331 with MLS gaskets)
2. reach that torque without compromising the integrity of my head studs
3. Do the above without pulling off the heads.


Factors bearing on the problem:
1. My engine is already assembled and running.
2. I currently have the standard ARP 1/2" head studs, which my engine assembler says are torqued to 105 lbs-ft.
3. ARP recommends against torquing them to more than 90 lbs-ft of torque (via phone) even though the way I read their chart recommends 95 lbs-ft.
4. ARP's best bolts are supposed to be torqued to 105 lbs-ft, which is just about what I want them to be torqued at.

References:
1. ARP Torque recommendation chart
2. ARP material tensile strength chart (needed to interpret the other chart)

Solution: Replace the standard bolts with the best ones offered.

Question: Almost like a retorque, can I pull one stud out at a time and replace it with a stud made of stronger material?
To clarify, I propose to take out the studs one at a time, and install new ones instead of pulling the heads off and replacing all of them at once. Is there any reason that I shouldn't?

Thanks for your help,

Chris

 

[Rick 91GT]

Chris that is no problem, you have a DART block right? Atleast the holes are blind so you don't have to worry about antifreeze or water.

I've ran the reg bolts at those tq levels with no issues, my understanding is ARP's recommended rates are around 80%, definitly tq the uppers with 10 more ftlbs on your combo. If you want to access your head bolts with out taking off the rockers in the future go with the 12pt nuts, USUALLY they allow you to sneak a socket in there. I have had to clearance the rocker stands to get the clearance at times.

When you untorque start from the outside corners first, then criss cross going towards the center, this will keep the head from warping. Tighten in the reverse or the standard tq pattern.

 

[FastDriver]

Thanks again, Rick. I was hoping to see your response.

Chris

 

[FastDriver]

When you untorque start from the outside corners first, then criss cross going towards the center, this will keep the head from warping. Tighten in the reverse or the standard tq pattern.

Wait, wouldn't it be better not to loosen all of the bolts at once so that the head can't shift? I was planning to loosen the center middle bolt and pull out its stud. Replace and then tighten in phases. Then move in order of the typical sequence doing one at a time. anything wrong with that?

 

[Rick 91GT]

Wait, wouldn't it be better not to loosen all of the bolts at once so that the head can't shift? I was planning to loosen the center middle bolt and pull out its stud. Replace and then tighten in phases. Then move in order of the typical sequence doing one at a time. anything wrong with that?

That should work, so are you going to replace them one at a time and tq them all to say 60, then go back and go 80, then go back and go 100-110?

 

[FastDriver]

Honestly, I think the reasoning for torquing in stages is to compress the head gasket evenly across all of the studs as you work your way up to the final clamping pressure. I'm guessing that with all of them already at 105 lbs-ft, it won't be necessary because the load has already been spread evenly. But, I plan to bring the torque up in stages on each nut anyway, since there are factors that I may not be considering, and because I am more confident that procedure will be successful than I am in any other procedure. So here's the way I intend to do it: I'd start with #1 nut in the torque sequence and bring it to say 60 ft-lbs, wait a minute, break it loose and take it to say 80, wait 1, then break loose then torque to 105. 105 is what my assembler already torqued the studs to. Then, I'd go to #2 nut in the sequence and do it the same way. The idea is to keep the clamping pressure at each nut the same as it is now before I move on to another nut. I think that will prevent any shifting of the gasket or uneven pressures across the head gasket, as opposed to taking each one to 60 lbs-ft one at a time, and then I end up with the outer nuts at 105 lbs-ft while the inner ones are only at 60.

After I'm done with the entire sequence, I'm going to go back to the #1 and break it loose and torque it to the final torque that I'm looking for. Depending on the material that the stud is made from, I'd like that to be around 120 on the top studs and 110 on the bottom, now.

I realize that this is going to be a hell of a workout. So, I'm drinking protein shakes and taking steroids in preparation for the event

Chris

 

[FastDriver]

Well, all of that was pretty much irrelevant unless I have ARP make a custom set of studs. To my suprise, they do not make an off-the-shelf 351W head stud of stronger material than 8740 chrome-moly. I'm having them price a custom set of ARP2000 studs for me. I don't think this is going to be the way to go, though. No one else seems to be doing this. So, I don't see why it would be necessary for me.

Chris