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Normal Torque, Bottoming Torque, Combined. Worst case. Generally, it will not be the full stress on the threads, but then you have the containment of the combustion event. While that may be under the pre-load values, it's an additive to the thread stress, and in the threaded area, the bolts will only be elastic in the upper non-thread region.
Unfortunately, no.
I am still unclear on the relevance of the bottoming out to clamp load/force applied between the two parts being bolted together.
Applying a force to the block, ie the stud being driven into the block in a tapered bore, and damaging / cracking the block, I get that part.
But - I’m not understanding why whether the stud is tight at the bottom of the bore or 1/4 inch above the bottom, in my mind the nut will still tighten down the same amount (assuming the stud does not turn with the nut). That’s where I’m getting lost, or maybe Ive read it all wrong above??
Yes, the nut tightens down the same amount as it always did and pulls the stud up against the threads. That's not the problem. But when the stud is bottomed and turns more, it pushes against the bottom and stresses the threads in the same direction as the nut. So, the force in the threads is higher than what the nut does. It's additive.
Take any threaded hole with a bottom. Put a long bolt in it, and keep applying torque. Usually, the bolt thread will fail as it doesn't have the support that a threaded hole does, but if you do this with a block of aluminum, the aluminum threads will fail rather than the bolt, since the bolt has bottomed out.
I'm starting to have a hard time understanding why you don't understand this ... I don't know how else to explain it.
Yes, the nut tightens down the same amount as it always did and pulls the stud up against the threads. That's not the problem. But when the stud is bottomed and turns more, it pushes against the bottom and stresses the threads in the same direction as the nut. So, the force in the threads is higher than what the nut does. It's additive.
I'm starting to have a hard time understanding why you don't understand this ... I don't know how else to explain it.
Ok, Thank you. Now I understand what you are saying.
Now the three example diagram makes sense, I could not understand why the two arrows pointing up in example #3, vs #1. I was not understanding the stud pushing back up on the threads. I should have asked, ‘why two arrows?’
No, now that you are saying that, I could have noted it better in the diagram. I'm sidetracked by other things in my life.
When I used to write my technical reports, my director used to say that no one outside of our industry would understand what I was saying. There are times I don't open my perspective.
I just got off the phone with ARP tech this morning. They recommend.
1. Ensure the bore is clean, no fluids at the bottom to hydro lock and crack the block.
2. Locktite is up to the user, but not recommend if planning on reusing the studs. There is no benefit in this application, there are no harmonic vibrations to deal with.
3. Run the stud into the block all the way, finger tight when they bottom out. Not tool tight.
Im not going to beat a dead horse, I understand what TMT is describing about pulling threads out, I get that on bottoming a bolt.
But, I still don’t see how you would pull the lower block threads out, unless you bottom out the nut on the upper threads to start turning the bottom.
In particular if you are leaving the stud up 1 to 3/4 of a turn. In which there is no thread bottoming resistance, only frictional resistance to stop it from rotating, and you are still able to gain full torque, I fail to see how that could ever over torque the stud into the block and pull threads.
Had some time to get the engine harness finished up last night and started early on the driver's side this morning. Happy to get at least one side in. I did a few dry runs with the old heads and head gaskets earlier in the week to be sure it would go smoothly.
Break for daughter's soccer and hopefully get started again this afternoon. Supposed to be 102 today so we'll see. At the very least I should be able to get the other side in and hopefully everything torqued tonight or tomorrow morning.
I have to correct my statement, the stud does not touch the ground of the bore. I am currently working on an 03 engine. I sprayed paint into the threaded hole and screwed the stud in up to the end of the thread. The thread is not completely threaded to the bottom of the hole, so the stud touches NOT the bottom of the hole when you screw it in all the way. It was difficult to photograph, but I think you can see it. After screwing in and removing the stud, the silver paint on the bottom of the bore was undamaged.
Thanks for clearing that up. But if the stud thread still bottoms where the thread stops, there will still be upward force on the threads in the same direction as the nuts' tension.
Interesting the stud will not bottom out when reaching the end of the threading. I like the block off you are using, did you make those somehow? I used foam backer rod in the round holes and paper towels in the lifter cutouts.
Got both sides torqued, happy about that. No movement on the studs at all while torquing. Driver's side was much harder to do but at least I did not need to mess with any of the engine or transmission mounts. The socket and torque wrench fit just fine on the back corner. Turned engine over by hand and all valves/rockers look good on both sides. Fingers crossed, that is my biggest concern something with a push rod or lifter.
Maybe do the oil rails and valve covers later. No rush, after all it is Sunday and supposed to cool off this week. Nice to see the parts going on and clearing up some space in the garage. Hopefully have it running in a few more days.
Well got it running tonight. Sounded good and started quickly on the first try. Prior to starting I changed the oil and cranked it from under the hood 3 times for 10 seconds or so each time with 5 minutes of rest in between.
Only ran it for a few seconds because the belt was not on. Why wasn't the belt on?? Well the AC compressor I got had the wrong pulley. Imagine that so I'm trying to figure out what to do with it. Put the pulley from the original on it, get another pulley, or just get another compressor altogether and send that one back? Going to sleep on it.
Glad it started, seems good so far. Hopefully I can get the AC worked out tomorrow and get the rest put back together.
Last edited by billbot; May 15, 2025 at 08:13 AM.
Reason: Typo
Had a busy few days after the compressor fiasco. Put a new Motorcraft compressor the other day. Still gotta send the other one back to rockauto....
Thankfully got some time tonight to do some more work. Put the grille and headlights in and took the truck out tonight and it felt great. Ran around for 15-20 minutes to get up to temp. Shut her down in the driveway and hot started fine.
Still need to do the AC and put the bumper back on but everything else is done.
For anyone considering doing the studs, it's very doable but a lot of work. No way I would do it under a time crunch. My hat's off to the mechanics out there.
Did it in frame with the front end pulled off. Really opened it up. It was really weird at first working on the truck while standing on the ground or sway bar/frame. So used to doing everything from above.
Here's a picture when doing a dry run on the head install using the original head and head gasket. My hoist was about at its limit for reach.
Got the AC done tonight and put the bumper back on while vacuuming the system before recharge. Also tested coolant pressure, all good there. Max overall pressure at 7psi. Got a few more minor things to do, planning to take my boat out next weekend so that will be the real test.
