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Making progress just haven't had much time lately. Just about everything has been delivered. Still waiting on the rocker box gaskets though, supposed to be delivered tomorrow. Block is ready and threads cleaned. Also doing all new AC parts and got the compressor in today and BPD oil cooler mounted to the new condenser. Still need to fix a few connections on the engine harness, then planning to put the heads in this weekend.
I have a question on the lube for the studs. The instructions mention putting the lube on the stud threads, washers and nuts....is that both ends of the stud threads and both sides of the washer? Seems like there's conflicting information on that.
Aren't both ends 14mm, just different thread pitch, the top end fine thread?
In the instructions for the Powerstroke studs, ARP does not say to put the lube on the threads going into the block. However, in some of their other technical information, they say to do it.
Outside of ARP, the technical reason for putting some lubrication, including anti-seize, is to prevent vibrational, or tension-variation galling. Tension variation occurs during the combustion event. This is the head stud operational area.
I used engine oil, but I would not use the ARP Lube on the threads going into the block. I know some have, but its lubricity is too high for me to use it for threads that won't have frictional rotation, and will only be in a non-rotational installation.
The block thread is standard thread M14 (×2), the fine thread at the top is M14x1.5.
I blow out the block bore with compressed air, a fine film of oil still remains on the threads. I turn the studs to the bottom of the hole, then back three quarters of a turn. Despite the larger thread pitch, sometimes the stud rotades s little bit when the heads are getting
torqued down which distorts the torque. I had already considered gluing in the studs under preload so that this doesn't happen.
I had the same thing happen, but I marked the studs and nuts to watch for this. Once you achieve a high enough torque, the studs no longer rotate. But I used an Allen wrench to keep the stud from rotating in the moving state. If they both moved under high torque, I remarked on the location at the end.
I also have my studs and nuts marked so I can see if there is any movement of either or both together. I think that is important. I'll pull some images from videos of the work.
. I turn the studs to the bottom of the hole, then back three quarters of a turn. Despite the larger thread pitch, sometimes the stud rotades s little bit when the heads are getting torqued down which distorts the torque.
I had already considered gluing in the studs under preload so that this doesn't happen.
My ignorance is on full display here.
I don’t understand the above: Why back the stud off from the bottom 3/4 turn? Is there a concern they will be driven into the block further when torquing them down? How does it distort the torque?
If installing studs, what would recommend to use for a locktite / thread locker when installing?
Hartwig wow that is really helpful info. The pretensioning is a great recommendation as well as I feel 1/2 to 3/4 turn from the bottom. The video is excellent. Thank you.
TooManyToys your insight on the threads is helpful. I think what I will do is wipe a rag with 30 weight oil on the threads then. Also want to mention I have seen your videos on YouTube and they are excellent as well. Thank you for taking the time to put those together. Also for some reason the links did not work for me.
JJF20 I am not an expert in this area by any means but it is my understanding that the reason the studs are backed out is that they will turn some as the nuts are getting torqued. If they are bottomed out at the beginning, the extra force can crack the block. That is what I have heard mention of in a few videos anyway.
Away from the bottom is a common practice; I did it, too. The concern is bottoming out the stud. With the bottoming and some rotation, tremendous forces can be exerted on the bottom threads, which adds to the normal pre-load or clamping force normally applied. You don't want to strip out the block threads. I know of one person who has done that.
I just corrected my images above. I don't know why this site is having an issue with me putting them up now.
I'll see if I can put together the remnants of the videos I still have on my tightening of the studs.
Well explained, Jack.
In my opinion, another aspect for turning back is the fact that the bottom of the bore is not straight, it is tapered. A bolt that presses on this bevel acts like a wedge and the risk of causing a crack increases enormously.
There are even studs that are tightened even more. I would never install something like that.
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.
Edited.
The first diagram shows the upward force on the threads from the nut being torqued down.
The second diagram shows the upward force from the stud bottoming out and full torque applied to it (it won't be full torque, but for demonstration purposes).
The third diagram shows both forces from the nut and the stud bottoming now applied to the threads in the block. The force on the block threads is doubled.
Well explained, Jack.
In my opinion, another aspect for turning back is the fact that the bottom of the bore is not straight, it is tapered. A bolt that presses on this bevel acts like a wedge and the risk of causing a crack increases enormously.
There are even studs that are tightened even more. I would never install something like that.
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